mm. The triangular meshes of the Sagosphærida are therefore on an average

ten times as large as the usual meshes in the network of the common #Sphæroidea#.

The filiform bars, or the thread-shaped, very long and thin rods between the triangular meshes, are scarcely less characteristic of the Sagosphærida than the form and size of the meshes. Their length is usually between 0.1 and 0.2 mm., often also {1604}from 0.2 to 0.3 mm., whilst their thickness is only 0.002 to 0.004 mm., often it is less than 0.001, rarely more than 0.005 mm. The nodal points of the network, in which six threads are usually united, are more or less thickened, often stellate (Pl. 108, figs. 9, 12, &c.). Sometimes they are pierced by a central pore. The thin threads are constantly cylindrical, never edged or prismatic, very elastic and flexible; usually they are perfectly smooth, rarely spiny or thorny, sometimes provided with scattered cruciate verticils of lateral branches, as in _Sagena crucifera_ and in the first described form of this family, _Sagmarium trigonizon_ (compare my Monograph, 1862, Taf. xxvi. fig. 5).

The surface of the spherical shell is smooth only in two genera of Sagosphærida, in _Sagena_ and _Sagmarium_ (Pl. 108, figs. 2, 8). In the five other genera it is covered either with radial spines, arising from the nodal points of the network, or with peculiar cortical pyramids or tent-shaped elevations (Pl. 108, figs. 1, 3-6, &c.). These pyramids are of the same characteristic shape as in the similar _Auloscena_ among the Aulosphærida (Pl. 110, fig. 1); usually, however, they are less regular than in the latter. The pyramids or tents are usually six-sided, often, however, they are also four-sided or three-sided, more rarely five, seven or more sided. The edges of the pyramids are formed by filiform bars similar to those which compose the original lattice-work of the Sagosphærida. The cavity of the pyramids is quite simple in _Sagoscena_ (figs. 1, 5, 6), whilst in _Sagenoscena_ and _Sagoplegma_ a radial column arises in its axis, the thickened axial rod (figs. 3, 4, 10).

The radial spines, which arise either from the tops of the pyramids or from the nodal points of the network, exhibit in the Sagosphærida a variety and elegance similar to the closely allied Aulosphærida. Sometimes a single radial spine arises in each nodal point or at the top of each pyramid (figs. 3, 4, 10); at other times two, three, or four (rarely more) divergent spines (figs. 6-9, 12, 13). These are rarely quite simple, usually provided with lateral and terminal branches. The lateral branches are either scattered irregularly, or regularly disposed in elegant verticils, each of which is usually composed of three or four short branches (Pl. 108, figs. 9, 13). The terminal branches form either a similar verticil, or a bunch or corona, composed of numerous radial secondary spines. The distal ends of the terminal as well as of the lateral branches are rarely simple, usually they are provided with a spinulate knob or with an elegant spathilla (Pl. 108, figs. 3, 9, 13).

The _central capsule_ of the Sagosphærida is comparatively small, as it also is in the Aulosphærida and Orosphærida. Its diameter is usually about one-third or one-fourth that of the enveloping shell, between 0.2 and 0.3, often only 0.12 to 0.18, rarely more than 0.3 mm. It is surrounded on the oral half by a red or dark phæodium and separated from the inner surface of the shell by the voluminous calymma. The subspherical nucleus is usually about half as broad as the capsule. The three openings of the latter, the large tubular astropyle and the two opposite lateral parapylæ, exhibit the same shape {1605}as in the closely allied Aulosphærida (Pl. 111, fig. 3). The pseudopodia arising from the central capsule form a loose network in the calymma, and proceed over its surface as numerous delicate radial filaments, often supported by the radial spines.

_Synopsis of the Genera of Sagosphærida._

------------------------------------------------------------------------- I. Subfamily Sagenida. Wall of the spherical shell composed of a simple lattice-plate with or without pyramidal elevations. ------------------------------------------------------------------------- { No radial spines, surface Surface of the spherical { smooth, 675. _Sagena_. shell smooth or spiny, { without pyramidal { Radial spines in the nodal elevations. { points, 676. _Sagosphæra_.

Surface of the spherical { Pyramids without internal shell covered with { axial rod, 677. _Sagoscena_. pyramidal or tent- { shaped elevations. { Pyramids with an internal { radial axial rod, 678. _Sagenoscena_. ------------------------------------------------------------------------- II. Subfamily Sagmarida. Wall of the spherical shell spongy, composed of an irregular complicated wicker-work. ------------------------------------------------------------------------- Surface of the spherical { Surface smooth, without shell smooth or spiny, { radial spines, 679. _Sagmarium_. without pyramidal { elevations. { Surface studded with { radial spines, 680. _Sagmidium_.

Surface of the spherical { Pyramids on the top with a shell covered with { radial spine or a bunch pyramidal elevations. { of divergent spines, 681. _Sagoplegma_.

Subfamily 1. SAGENIDA, Haeckel.

_Definition._--#Sagosphærida# with a delicate spherical shell, the thin wall of which is composed of a simple lattice-plate, not spongy.

Genus 675. _Sagena_,[294] n. gen.

_Definition._.--#Sagosphærida# with a delicate shell, the thin wall of which is composed of a simple smooth lattice-plate, without radial spines.

The genus _Sagena_ is the simplest of the Sagosphærida and may be regarded as the common ancestral form of this family. The delicate wall of the simple spherical lattice-shell is composed of large, regular, or subregular, triangular meshes, the nodal points of which bear no radial spines. It agrees therefore perfectly with _Aularia_, and differs from this simplest form of Aulosphærida only in the structure of the skeleton, which is composed not of hollow articulated tubes, but of very thin solid threads. The skeleton may therefore also be confounded with _Cenosphæra_, but the central capsule of this latter is "peripylean," with numerous fine pores in the entire wall, whilst that of _Sagena_ is "tripylean," having the proboscis of all PHÆODARIA.

{1606}1. _Sagena ternaria_, n. sp. (Pl. 108, fig. 8).

Network subregular, with equilateral triangular meshes, intermingled with single irregular meshes (fig. 8). Bars of the network smooth, its nodal points solid, not pierced.

_Dimensions._--Diameter of the spherical shell 1.5 to 2.5, length of the bars 0.1 to 0.2, breadth 0.002 to 0.005.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

2. _Sagena pertusa_, n. sp.

Network subregular, with nearly equal triangular meshes. Bars of the network smooth, its nodal points pierced by a circular hole.

_Dimensions._--Diameter of the shell 1.2 to 1.8, length of the bars 0.2 to 0.25, breadth 0.003.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

3. _Sagena triangula_, n. sp.

Network very regular, with equilateral triangular meshes. Bars of the network spinulate, like those of _Sagoplegma spinulosa_. (Pl. 108, fig. 14), its nodal points solid, not pierced.

_Dimensions._--Diameter of the shell 2.2, length of the bars 0.25, breadth 0.004.

_Habitat._--South Atlantic, Station 325, surface.

4. _Sagena crucifera_, n. sp.

Network more or less irregular, with unequal triangular meshes. Bars of the network studded with scattered, rectangular, minute crosses, arising perpendicularly, each cross composed of four small equal bars. Nodal points partly solid, partly pierced by a hole. Network very similar to that of _Dictyosoma trigonizon_, figured in my Monograph, Taf. xxvi. figs. 4, 5.

_Dimensions._--Diameter of the shell 1.5, length of the bars 0.1 to 0.2, breadth 0.003.

_Habitat._--Mediterranean, Atlantic, Canary Islands, Station 353, surface.

Genus 676. _Sagosphæra_,[295] n. gen.

_Definition._--#Sagosphærida# with a delicate spherical shell, the thin wall of which is composed of a simple lattice-plate, and bears on its nodal points radial spines.

The genus _Sagosphæra_ differs from the preceding _Sagena_, its ancestral form, in the development of radial spines on the nodal points of the simple delicate lattice-sphere. It exhibits therefore the same relation to the latter as _Aulosphæra_ bears to _Aularia_. {1607}The regular or subregular triangular meshes of the lattice-sphere are separated in _Sagosphæra_ by solid, very thin threads, in the similar _Aulosphæra_, however, by thicker hollow tubes. The genus _Sagosphæra_ may be divided into two subgenera:--_Sagosphærella_ with a single radial spine at each nodal point of the network, and _Sagosphæroma_ with a bunch of two to four or more divergent radial spines.

1. _Sagosphæra trigonilla_, n. sp.

Radial spines simple, straight, smooth, about as long as the smooth bars of the network, a single one at each nodal point. Meshes very regular, of equal size, equilateral triangular. (Similar to the common _Aulosphæra trigonopa_.)

_Dimensions._--Diameter of the sphere 1.2 to 1.8, length of the bars 0.1 to 0.2, breadth 0.002 to 0.006.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

2. _Sagosphæra penicilla_, n. sp. (Pl. 108, fig. 10).

Radial spines straight, stout, a single one at each nodal point, twice as thick, but of the same length as the smooth bars of the network, armed at the distal end with a brush of numerous thin radial bristles. (Very similar to _Sagenoscena penicillata_, but without pyramidal elevations on the surface of the sphere.)

_Dimensions._--Diameter of the sphere 1.0 to 1.5, length of the bars 0.1 to 0.15, breadth 0.002 to 0.004.

_Habitat._--Antarctic Ocean, Station 154, surface.

3. _Sagosphæra verticilla_, n. sp.

Radial spines slender, slightly curved, a single one at each nodal point, armed with three to five cruciate verticils, each of which is composed of four crossed lateral branches with spinulate terminal knobs (similar to _Sagmidium crucicorne_, Pl. 108, fig. 9), but with a spherical shell, having a simply latticed, and not a spongy wall.

_Dimensions._--Diameter of the sphere 2.0 to 2.5, length of the bars 0.1 to 0.2, breadth 0.002.

_Habitat._--North Pacific, Station 256, surface

4. _Sagosphæra furcilla_, n. sp. (Pl. 108, figs. 11, 11_a_).

Radial spines short, spinulate, with a spiny terminal knob (fig. 11_a_), two or three arising from each nodal point of the network in divergent directions, only one-third or one-fourth as long as its smooth bars. Meshes more or less irregular, triangular.

_Dimensions._--Diameter of the sphere 2.2, length of the bars 0.2 to 0.3, breadth 0.004.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

{1608}5. _Sagosphæra coronilla_, n. sp.

Radial spines slender, smooth, three to six arising from each nodal point of the network in divergent directions, about as long as its smooth bars, crowned at the distal end with a bunch of twenty to thirty radial terminal branches, and provided with a spinulate knob at the distal end (similar to _Sagenoscena stellata_, Pl. 108, fig. 3).

_Dimensions._--Diameter of the sphere 3.0, length of the bars 0.1 to 0.2, breadth 0.002.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

Genus 677. _Sagoscena_,[296] n. gen.

_Definition._--#Sagosphærida# with a delicate spherical shell, the thin wall of which is composed of a simple lattice-plate and covered with numerous pyramidal elevations; each pyramid bears on its top one or more radial spines, but has no axial rod in its radial axis.

The genus _Sagoscena_, and the following closely allied _Sagenoscena_ (both very common and widely distributed), exhibit a peculiar and very remarkable structure of the delicate lattice-shell, similar to that which _Auloscena_ represents among the Aulosphærida. The surface of the simple spherical lattice-shell is covered with numerous pyramidal or tent-shaped elevations. These elegant and delicate pyramids are, however, in _Sagoscena_ usually not so regular as in the similar _Auloscena_; the edges of the pyramids are in the latter hollow cylindrical tubes, in the former thin solid threads. The top of each pyramid usually bears a bunch of apical spines.

1. _Sagoscena castra_, n. sp. (Pl. 108, fig. 1).

Pyramids subregular, of equal size and similar form, usually three-sided, crowned at the top with three divergent apical spines, which alternate with the three edges of the pyramids and bear a small spinulate terminal knob. (Some four-sided and single five-sided pyramids are often intermingled with the three-sided.)

_Dimensions._--Diameter of the sphere 1.7 to 2.3, length of the bars 0.2 to 0.25, breadth 0.008.

_Habitat._--South-Eastern Pacific, Stations 295, 296, surface.

2. _Sagoscena tentorium_, n. sp. (Pl. 108, fig. 6).

Pyramids subregular, of equal size and similar form, usually four-sided, crowned at the top with three divergent apical spines, which are trifurcate at the distal end. (Some three-sided and five-sided pyramids are often intermingled with the four-sided.)

_Dimensions._--Diameter of the sphere 2.2, length of the bars 0.2 to 0.25, breadth 0.005.

_Habitat._--South Pacific, Station 291, surface.

{1609}3. _Sagoscena prætorium_, n. sp. (Pl. 108, fig. 7).

Pyramids subregular, of equal size and similar form, usually four-sided, crowned at the distal top with three or four divergent apical spines, which bear some irregular verticils of lateral and terminal branches. (Some five-sided and some six-sided pyramids are often intermingled with the four-sided.)

_Dimensions._--Diameter of the sphere 2.6, length of the bars 0.3, breadth 0.006.

_Habitat._--Central Pacific, Stations 271 to 274, surface.

4. _Sagoscena pellorium_, n. sp. (Pl. 108, fig. 5).

Pyramids subregular, of equal size and similar form, usually five-sided or six-sided, crowned at the distal end with three to six divergent apical spines, which bear an irregularly spinulate terminal knob. (The size and form of the apical spines is here very variable, as well as the number of the edges of the pyramids, which varies between three and six.)

_Dimensions._--Diameter of the sphere 3.2, length of the bars 0.15 to 0.25, breadth 0.008.

_Habitat._--Antarctic Ocean, Station 156, surface.

5. _Sagoscena cruciarium_, n. sp.

Pyramids subregular, usually six-sided (intermingled with single five-sided and seven-sided or eight-sided forms), crowned at the distal top with three divergent, slender, apical spines, each of which bears three to six regular cruciate verticils; the four crossed lateral branches of each verticil bearing a spinulate terminal knob. (Similar to _Sagoplegma scenophora_, Pl. 108, fig. 13.)

_Dimensions._--Diameter of the shell 2.5, length of the bars 0.2 to 0.3, breadth 0.004.

_Habitat._--North Pacific, Stations 240 to 244, surface.

6. _Sagoscena debilis_, n. sp.

Pyramids more or less irregular, with four, five, or six sides, of somewhat different form and unequal size; crowned at the top with one, two, or three slender apical spines, of variable length. These spines as well as the bars of the network bear scattered cruciate verticils, each usually composed of four crossed, small, lateral branches.

_Dimensions._--Diameter of the shell 2 to 3.0, length of the bars 0.1 to 0.15, breadth 0.003.

_Habitat._--Central Pacific, Stations 263 to 274, surface.

7. _Sagoscena gracilis_, Haeckel.

_Aulosphæra gracilis_, R. Hertwig, 1879, Organism. d. Radiol., p. 91, Taf. ix. fig. 4.

Pyramids more or less irregular, with five, six, or seven sides, often of somewhat different form and unequal size; crowned at the top with a single radial spine, which has the same size as the {1610}bars of the network, and bears in its distal half four cruciate verticils, each composed of four crossed and curved horizontal branches.

_Dimensions._--Diameter of the sphere 1 to 2, length of the bars 0.08 to 0.09, breadth 0.002.

_Habitat._--Mediterranean (Messina), surface.

8. _Sagoscena fragilis_, n. sp.

Pyramids very irregular, with four to eight sides, of different form and unequal size; crowned at the top with a single, slender, radial spine, of the same thickness as the slender bars of the network; the latter as well as the former are smooth, without lateral branches.

_Dimensions._--Diameter of the sphere 1.0 to 2.0, length of the bars 0.1 to 0.2, breadth 0.001 to 0.002.

_Habitat._--Cosmopolitan; Atlantic, Pacific, surface.

Genus 678. _Sagenoscena_,[297] n. gen.

_Definition._--#Sagosphærida# with a delicate spherical shell, the thin wall of which is composed of a simple lattice-plate and covered with numerous pyramidal elevations; each pyramid bears on its top one or more radial spines, and has an internal axial rod in its radial axis.

The genus _Sagenoscena_ differs from the preceding closely allied _Sagoscena_ in the possession of an internal radial axial rod, which arises in the centre of the base of each pyramid, and is prolonged usually over its apex into a free, radial, apical spine. The distal end of the latter is usually armed with a bunch of terminal teeth or bristles. In the similar _Sagoscena_ the internal cavity of the pyramids is simple, without axial rod.

1. _Sagenoscena stellata_, n. sp. (Pl. 108, fig. 3).

Pyramids rather regular, usually six-sided (intermingled with single five-sided and four-sided forms); their axial rod and its prolongation, the radial apical spine, three to four times as thick as the slender edges of the pyramid. The distal end of the apical spine bears an elegant star of numerous radially divergent terminal branches, each of which is armed with a spinulate terminal knob.

_Dimensions._--Diameter of the sphere 3.5 to 4.0, length of the net bars 0.3, breadth 0.003; length of the radial spines 0.2, breadth 0.012.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

2. _Sagenoscena ornata_, n. sp. (Pl. 108, fig. 4).

Pyramids rather regular, usually six-sided (intermingled with single five-sided and seven-sided forms); their axial rod and apical spine spindle-shaped, two to four times as thick as the smooth bars {1611}of the network. The distal end of the radial spines bears an elegant, foliate, terminal knob, composed of four to six vertical pinnate leaves, lying in crossed meridional planes.

_Dimensions._--Diameter of the sphere 2 to 3, length of the rods 0.1 to 0.2, breadth 0.003 to 0.01.

_Habitat._--Antarctic Ocean, Station 156, depth 1975 fathoms.

3. _Sagenoscena penicillata_, n. sp. (Pl. 108, fig. 10).

Pyramids rather regular, usually six-sided (intermingled with single five-sided, seven-sided, and eight-sided forms); their axial rod and apical spine spindle-shaped, thicker than the smooth bars of the network. The distal end of the radial spines is penicillate and bears a brush of bristle-shaped, radial, terminal spinules (compare _Sagosphæra penicilla_, p. 1607).

_Dimensions._--Diameter of the sphere 1 to 1.5, length of the bars 0.1 to 0.15, breadth 0.004 to 0.005.

_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.

4. _Sagenoscena coronata_, n. sp.

Pyramids rather regular, usually four-sided (intermingled with single five-sided and six-sided forms); their axial rod and apical spines cylindrical, scarcely thicker than the smooth bars of the network. The distal end of the radial spines bears a corona of twenty to thirty curved terminal branches, which form a regular circle, and are armed with a spinulate terminal knob.

_Dimensions._--Diameter of the sphere 2 to 3, length of the bars 0.12 to 0.18, breadth 0.004 to 0.008.

_Habitat._--North Pacific, Station 256, surface.

5. _Sagenoscena spathillata_, n. sp.

Pyramids more or less irregular, of different sizes and various forms, each composed of four to eight convergent rods and a central axial rod. The latter is prolonged into a free apical spine, which bears at the distal end a spathilla of eight to twelve recurved teeth, and often beyond it a second similar verticil.

_Dimensions._--Diameter of the sphere 4.0, length of the bars 0.1 to 0.2, breadth 0.002.

_Habitat._--Arctic Ocean, Greenland (Olrik).

6. _Sagenoscena cruciata_, n. sp.

Pyramids very irregular, of different sizes and various forms, each composed of six to nine convergent rods and a central axial rod. The latter is prolonged into a free apical spine, which bears three to five cruciate verticils, each composed of four perpendicularly crossed lateral branches which bear at the distal end a spinulate knob (similar to _Sagmidium crucicorne_, Pl. 108, fig. 9).

_Dimensions._--Diameter of the sphere 1.0 to 1.2, length of the bars 0.06 to 0.09, breadth 0.001.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.

{1612}Subfamily 2. SAGMARIDA, Haeckel.

_Definition._--#Sagosphærida# with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework.

Genus 679. _Sagmarium_,[298] n. gen.

_Definition._--#Sagosphærida# with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework, and exhibits a smooth surface, without radial spines and pyramidal elevations.

The genus _Sagmarium_, and the following two genera of Sagosphærida, represent together the subfamily Sagmarida, differing from the preceding Sagenida in the spongy structure of the shell-wall. Whilst in the latter the thin wall of the delicate spherical shell is composed of a simple lattice-plate with triangular meshes, in the former numerous branches diverge from the nodal points of these meshes, and produce by union an irregular and loose spongy framework. The surface of this spongy hollow sphere (similar to _Plegmosphæra_) is in _Sagmarium_ smooth.

1. _Sagmarium spongodictyum_, n. sp. (Pl. 108, fig. 2).

Spongy wall of the hollow sphere about half as thick as the radius of its cavity. Bars of the spongy framework very thin and fragile, smooth, without thorns.

_Dimensions._--Diameter of the sphere 2.0 to 2.4; length of the bars 0.1 to 0.2, breadth 0.001.

_Habitat._--South Atlantic, Station 333, surface.

2. _Sagmarium plegmosphærium_, n. sp. (Pl. 108, fig. 14).

Spongy wall of the hollow sphere about one-fourth as thick as the radius of its cavity. Bars of the spongy framework rather stout, studded with numerous small spines, which arise perpendicularly from their surface.

_Dimensions._--Diameter of the sphere 1.2 to 1.5, length of the bars 0.1 to 0.16, breadth 0.004.

_Habitat._--Tropical Atlantic, Station 347, surface.

3. _Sagmarium trigonizon_, Haeckel.

_Dictyosoma trigonizon_, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 841.

_Spongodictyon trigonizon_, Haeckel, 1863, Monogr. d. Radiol., p. 459, Taf. xxvi. figs. 4, 5.

Bars of the spongy framework thin, irregularly curved, bearing scattered small crosses, which are composed of four small rods arising perpendicularly from the bars. Nodal points of the {1613}framework partly pierced by a hole. The peculiar network of a complete specimen, observed by me at Portofino in 1880, was so similar to that of _Spongodictyon trigonizon_, described above (p. 91), and figured in 1862 in my Monograph, that I am doubtful if the two forms are not identical, the two medullary shells of the latter being accidentally entangled in the framework. (Compare p. 1602.)

_Dimensions._--Diameter of the sphere 1.1 to 1.5, length of the bars 0.1 to 0.2, breadth 0.002.

_Habitat._--Mediterranean (Messina, Portofino), surface.

Genus 680. _Sagmidium_,[299] n. gen.

_Definition._--Sagosphærida with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework, and bears on the nodal points of its surface radial spines.

The genus _Sagmidium_ differs from the preceding _Sagmarium_ in the development of radial spines on the surface of the spongy hollow sphere. It bears therefore the same relation to the latter as _Sagosphæra_ does to _Sagena_, and may be derived either from _Sagmarium_ by the formation of radial spines, or from _Sagosphæra_ by development of the spongy envelope.

1. _Sagmidium unicorne_, n. sp.

Radial spines simple, straight, smooth, a single one at each nodal point of the surface of the spongy sphere, bearing on its distal end a spinulate knob, or a bunch of numerous radial bristles. (Similar to _Sagenoscena penicillata_, Pl. 108, fig. 10.) Bars of the spongy framework smooth.

_Dimensions._--Diameter of the sphere 3.0 to 3.5, length of the bars 0.15 to 0.2, breadth 0.003 to 0.006.

_Habitat._--Antarctic Ocean, Station 256, surface.

2. _Sagmidium tricorne_, n. sp.

Radial spines simple, smooth, usually three divergent united at each nodal point of the surface (sometimes two or four instead of three). Each spine bears on its distal end three short divergent conical teeth. (Similar to the terminal teeth of _Sagoscena tentorium_, Pl. 108, fig. 6.) Bars of the spongy framework smooth.

_Dimensions._--Diameter of the sphere 1.6 to 2.4, length of the bars 0.06 to 0.09, breadth 0.001 to 0.002.

_Habitat._--Central Pacific, Stations 263 to 268, surface.

3. _Sagmidium crucicorne_, n. sp. (Pl. 108, fig. 9).

Radial spines slender, verticillate, three or four divergent arising from each nodal point of the surface. Each spine bears three to six cruciate verticils of lateral branches; each verticil being {1614}composed of four crossed small branches with a spinulate terminal knob. Bars of the spongy framework partly covered with similar verticils.

_Dimensions._--Diameter of the sphere 2.0 to 3.0, length of the bars 0.2 to 0.3, breadth 0.002 to 0.003.

_Habitat._--North Pacific, Stations 240 to 244, surface.

4. _Sagmidium quadricorne_, n. sp. (Pl. 108, fig. 12).

Radial spines stout, smooth, cylindrical, usually four divergent arising from each nodal point of the surface (sometimes three, five, or six, instead of four). Each spine bears on its distal end a club-shaped stellate knob. Bars of the spongy framework smooth.

_Dimensions._--Diameter of the sphere 4.5, length of the bars 0.2 to 0.3, breadth 0.003 to 0.005.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

5. _Sagmidium multicorne_, n. sp.

Radial spines slender, more or less curved, verticillate, in variable number (three to six) divergent, arising from the nodal points of the surface. The spines as well as the bars of the spongy framework are partly simple, partly covered with irregularly scattered cruciate verticils, very similar to those of _Sagmarium trigonizon_ (or _Dictyosoma trigonizon_), figured in my Monograph, pl. xxvi. figs. 4, 5.

_Dimensions._--Diameter of the sphere 5.0, length of the bars 0.2 to 0.3, breadth 0.003.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.

Genus 681. _Sagoplegma_,[300] n. gen.

_Definition._--#Sagosphærida# with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework, and bears on its surface numerous pyramidal elevations.

The genus _Sagoplegma_ differs from _Sagmarium_, its ancestral form, in the development of pyramidal or tent-shaped elevations on the surface of the spongy hollow sphere. It exhibits, therefore, the same relation to the latter as the similar _Sagoscena_ bears to _Sagena_. The wall of the spherical shell is in the two latter genera a thin simple lattice-plate, in the former a thickened spongy framework.

1. _Sagoplegma pyramidophora_, n. sp.

Pyramids on the surface of the spongy sphere subregular, mostly tetrahedral, of nearly equal size and similar form. The three edges of each pyramid are prolonged over its top into three {1615}short, divergent, apical spines which are forked at the distal end. (Very similar to _Sagoscena castra_ and _Sagoscena tentorium_, Pl. 108, figs. 1, 6, probably derived from them, but differing in the spongy structure of the thickened shell-wall, which is half as thick as the radius of its cavity.)

_Dimensions._--Diameter of the sphere 2.0 to 2.5, length of the bars 0.15 to 0.2, breadth 0.002.

_Habitat._--North Pacific, Stations 231 to 239, surface.

2. _Sagoplegma scenophora_ n. sp. (Pl. 108, fig. 13).

Pyramids on the surface of the spongy sphere irregular, with three to six sides, unequal in size and different in form. The edges of each pyramid are prolonged over its top into three to six divergent apical spines, which bear three to six cruciate verticils, each composed of four small, crossed, lateral branches, armed with a spinulate knob at the distal end.

_Dimensions._--Diameter of the sphere 3.0 to 3.5, length of the bars 0.25 to 0.35, breadth 0.003.

_Habitat._--North Pacific, Stations 252, 253, surface.

Family LXXVI. #AULOSPHÆRIDA#, Haeckel (Pls. 109-111).

_Aulosphærida_, Haeckel, 1862, Monogr. d. Radiol., p. 357.

_Definition._--PHÆODARIA with a large spherical or subspherical (rarely spindle-shaped) articulated shell, which is composed of hollow tangential tubes. Nodal points of the loose network stellate, with a nodal cavity and astral septa. Meshes either triangular or polygonal. Hollow radial spines arise usually at the nodal points of the surface. No peculiar mouth in the shell. Central capsule tripylean, placed in the centre of the shell.

The family #Aulosphærida# comprises a great number of splendid and widely distributed PHÆODARIA, which have a special interest on account of the peculiarly complicated structure of their large lattice-shell, of the extraordinary beauty of their form and of their remarkable relations to the other PHÆODARIA. They differ from all the other Radiolaria in the peculiar articulate composition of the spherical skeleton of hollow tangential tubes, which are connected (and at the same time separated) by sutural or astral septa and filled up by jelly. The same peculiar structure recurs only in the closely allied Cannosphærida, which, however, differ in the possession of a second internal concentric shell, connected with the outer by radial beams. The similar Sagosphærida, which exhibit corresponding forms in various genera, differ from the Aulosphærida in the simpler structure of the delicate lattice-sphere, which is composed of very thin solid threads of silica, without astral septa. The Orosphærida, finally, also nearly related to the preceding families, differ from them in the coarse structure of the lattice-sphere, which is composed of very thick tangential, concentrically stratified rods, with an internal axial canal, but without astral septa at the nodal points.

{1616}One genus only, and two species, of Aulosphærida have been hitherto known, having been discovered by me in 1859 at Messina, and described in my Monograph in 1862 as _Aulosphæra trigonopa_ and _Aulosphæra elegantissima_ (_loc. cit._, p. 357, Taf. x. figs. 4, 5; Taf. ix. figs. 5, 6). The characteristic structure of their central capsule, as true TRIPYLEA, was afterwards, in 1879, described more accurately by Richard Hertwig (Organism. d. Radiol., p. 90, Taf. x. figs. 2, 8, 14). The rich collection of the Challenger has demonstrated that the Aulosphærida belong to the most common and most widely distributed PHÆODARIA; many of them are distinguished by the admirable elegance and astonishing regularity of their large and delicate shell. Nine genera and fifty-six species of this great family are described in the following pages, which, however, may represent only a small part of the numerous forms which are found on the surface as well as in different depths of all oceans and in all zones.

The shell is in the great majority of Aulosphærida a regular sphere or an endospherical polyhedron. Two genera only, both rather rare, exhibit a different monaxonial form, one vertical main axis being developed either more or less than all the other ones of the sphere:--_Aulatractus_ is spindle-shaped or ellipsoidal, with prolonged main axis; _Aulophacus_ is lenticular or discoidal, with shortened main axis. The former may be compared to the #Prunoidea#, the latter to the #Discoidea#, in opposition to the common regular #Sphæroidea#. The size of the lattice-shell is very considerable in all Aulosphærida, its diameter varying usually between 1 and 3 mm., often it amounts to 4 or 5 mm.; very rarely the diameter is more than 5 or less than 1 mm. The largest form observed is the spindle-shaped _Aulatractus_, in which the vertical prolonged main axis attains 6 to 10 mm., the horizontal equatorial axis 3 to 5 mm.

The network of the lattice-shell exhibits in the Aulosphærida two different types, according to which we distinguish two different subfamilies: Aularida and Aulonida; the former are much more common and richer in remarkable forms than the latter. The meshes of the network are in the Aularida constantly triangular, regular or subregular, and very similar to those of the Sagosphærida; at each nodal point six tangential tubes are usually united, so that the network may be regarded also as composed of regular hexagonal meshes, each of which is divided into six smaller triangular meshes (Pl. 109, figs. 1, 3, 5). The second subfamily, the Aulonida, are much rarer than the former, and are distinguished by the polygonal meshes of the network; these are usually more or less irregular, pentagonal and hexagonal intermingled, more rarely tetragonal, heptagonal, or octagonal; usually three or four, rarely five or more tangential tubes are united at each nodal point (Pl. 111, figs. 1, 3). The size of the meshes is very considerable, and agrees with that of the Sagosphærida; their diameter being usually between 0.1 and 0.3, rarely less or more.

The hollow tubes which compose the loose network are usually cylindrical, straight or slightly curved, smooth (Pl. 111, fig. 2), more rarely somewhat spinulate (Pl. 109, {1617}fig. 5). Their length is usually between 0.1 and 0.2 mm., rarely less than 0.08, or more than 0.24 mm.; their diameter usually between 0.003 to 0.005, sometimes only 0.002 or less, at other times 0.006 or more. In several species the tangential tubes are thinner in the middle part, and thickened towards the two ends (Pl. 109, figs. 3, 4). Each tube consists of a thin cylindrical wall of silex, and of a jelly-mass filling up its cavity; in its axis runs a very thin, straight or slightly curved thread of silica, the axial filament.

The arrangement of the tangential tubes, which originally, in the simplest Aulosphærida, lie tangentially in the spherical face of a simple lattice-sphere, exhibits various secondary modifications, leading to various interesting generic forms. Two genera only, _Aularia_ (with triangular meshes, Pl. 111, fig. 2) and _Aulonia_ (with polygonal meshes, Pl. 111, fig. 1) possess a smooth, perfectly simple lattice-sphere, and may therefore be regarded as the ancestral genera of the two subfamilies. Two other corresponding genera, the common _Aulosphæra_ (Pl. 109) and the rarer _Aulastrum_ (Pl. 111, fig. 3), differ from the former in the development of radial spines at the nodal points of the simple lattice-sphere. _Aulophacus_ may be developed from _Aulosphæra_ by shortening, _Aulatractus_, however, by prolongation of the vertical main axis (Pl. 111, figs. 6, 7). In two genera, _Auloplegma_ and _Aulodictyum_, the latticed wall of the spherical shell becomes thickened and spongy, an irregular framework being formed by tubes connected in different directions (Pl. 111, fig. 8). The most remarkable and the most elegant form, however, of the whole family is represented by _Auloscena_ (Pl. 110). The entire surface of the spherical lattice-shell is here covered with numerous regular or subregular pyramids, or tent-shaped elevations. Usually each pyramid is six-sided, and surrounded by six other six-sided pyramids, their bases being separated by six triangular meshes, which lie in the spherical face. A similar elegant form is developed among the Sagosphærida in the genera _Sagoscena_, _Sagenoscena_ and _Sagoplegma_ (Pl. 108, fig. 1). The structure of _Auloscena_, however, is usually more regular, and in the top of each pyramid a radial tube arises.

The junction of the cylindrical tubes at the nodal points of the network is very remarkable. _Aularia_, the simplest form of the family, exhibits at each nodal point the union of six tangential tubes (Pl. 111, fig. 2); their ends are so pointed and truncated that they are connected in the form of a regular six-radiate star; the conical end of each tube is separated from, and at the same time closely connected with, the adjacent conical ends of the two neighbouring tubes by a thin septum, the astral or sutural septum. The six astral septa compose together a six-radiate star, and in the centre of this star the six axial filaments of the tubes are united. Their central union is surrounded by a small, double-contoured circle, and this circle seems to be the perimeter of a small and flat cavity on the inside of the star, which we call shortly the "nodal cavity" ("die kleine Vertiefung" according to Hertwig, _loc. cit._, p. 90). The nodal cavity of _Aularia_ probably possesses a central opening on its inside and six small surrounding pores, which {1618}lead into the six connected tangential tubes. In _Aulosphæra_ and _Auloscena_, where a radial spine arises at each nodal point, its axial filament arises from the centre of the star, and is usually prolonged on the inside into a free centripetal beam (Pl. 109, figs. 6, 7; Pl. 110, figs. 4, 6). This centripetal beam is a slender, very thin, conical tube (often with a six-sided pyramidal base) and perhaps of great morphological interest as a rudiment, being homologous to the hollow radial beams which connect the two concentric spheres of the Cannosphærida. Possibly the Aulosphærida have been derived from the latter by loss of the inner shell and reduction of the radial beams; the centripetal beams which are found in many (but not in all) Aulosphærida, may be the last remnant of those radial beams. They contain also an axial filament, as a direct internal prolongation of that of the external radial spine. The axial filaments of the radial spines are usually connected with their thin wall by a variable number of scattered transverse threads, or sometimes even by thin transverse septa (Pl. 110, figs. 4-7, &c.). This structure corresponds to the similar axial filaments and their thin filiform transverse branches which we have found in other PHÆODARIA, _e.g._, in the Tuscarorida and Circoporida.

The Aulonida (with polygonal meshes) exhibit in general the same structure as the Aularida (with triangular meshes). But whilst in the latter usually six tangential tubes are united at each nodal point, in the former only three or four tubes become united. Therefore also the number of the small sutural partitions or astral septa, which radiate from the central openings of the nodal cavity, is six in the latter, three or four in the former. Correspondingly three or four small pores lead from the nodal cavity into the surrounding tangential tubes.

The true nature of the nodal points, and the intimate structure of the different parts here united, is a matter which it is very difficult to explain. It is a certain fact, well established by hundreds of observations, that in the complete and well-preserved skeletons which are perfectly purified by fire, or by hot mineral acids, and afterwards dried, all the tubes of the skeleton, the tangential as well as the radial cylinders, become filled up by air. Each tube contains usually one large cylindrical air-bubble, with two hemispherical ends. But the air-bubbles of the neighbouring tubes are completely separated one from another by the thin astral or sutural septa, and the air-bubble of the radial tubes is also separated from the former. The central cavity of each nodal point is therefore surrounded in the Aularida by six, in the Aulonida by three or four separate cylinders of air. This fact seems to be explained only on the supposition that each single tube has two terminal pores or fissures, which open into the two nodal cavities on its two ends. The radial tubes must also possess at least one small opening, probably on their base, and probably they have another on their distal apex. In no other way can it be explained, that in all complete, well-preserved and purified skeletons, each single tube constantly becomes easily filled by an air-bubble after drying.

In the living Aulosphærida the cavities of all tubes are filled up by a jelly-substance, {1619}which may be stained by carmine and is probably identical with the jelly of the calymma. The latter is probably in direct connection with the former by the central pore of the nodal cavity, which is placed on its inside and surrounded by the astral septa; these separate the tangential tubes, radiating from one nodal point, completely, and are thin and simple, but very solid lamellæ of silica. Therefore the nodal stars of broken shells usually remain united, whilst the single radiating tubes composing them are broken off (Pl. 110, figs. 3, 8, 10). But it happens only rarely (and only in certain individual species) that complete single tubes separate; usually the fragments of the connected neighbouring tubes remain on their ends. The two small terminal openings of each tangential tube, which lead from its cavity into the nodal cavity, and are surrounded on each end by the truncated ends of two neighbouring astral septa, are very difficult to observe (Pl. 110, figs. 8-10).

The wonderful elegance and the high complication of these regular skeletons of the Aulosphærida, produced by a single cell, becomes increased by the graceful and manifold appendages and apophyses which are usually developed on the radial tubes. In only a few species these are simple, as in the common and cosmopolitan _Aulosphæra trigonopa_. Usually lateral or terminal appendages are developed in great variety, a selection of which is figured in Pls. 109-111. The lateral branches are either irregularly scattered spines (Pl. 110, figs. 3-7) or regular verticils of cruciate or radiate spines; each verticil is usually composed of four perpendicularly crossed horizontal branches (Pl. 109, figs. 3, 4, 7, 10, &c.), more rarely of a greater number of radiating transverse branches.

The terminal appendages of the radial spines exhibit a striking similarity with those of the Aulacanthida (Pls. 102-105). They are either forks with two or three divergent branches (Pl. 111, figs. 3, 4), or regular crosses with four branches opposite in pairs (Pl. 109, figs. 2, 6, 7, 10), or elegant crowns or verticils, composed of numerous radiating branches (Pl. 110, figs. 1-6). The distal ends of the terminal as well as of the lateral branches are either simple, pointed, or armed with a spinulate knob, or with a terminal spathilla. The variety and elegance of these terminal ornaments, the function of which is that of capturing tentacles, is in the Aulosphærida not less admirable than in the Aulacanthida and Coelodendrida.

The _central capsule_ of the Aulosphærida (Pl. 111, fig. 2) was first figured in my Monograph (1862, Taf. xi. fig. 5) of _Aulosphæra elegantissima_, as a sphere of 0.2 to 0.3 mm. in diameter. I described there the large nucleus (of half that size) as a spherical "Binnenblase," and the numerous pseudopodia which arise from the capsule and radiate through the meshes of the lattice-shell. But I had not observed at that time the three typical openings of the capsule, which were first discovered and accurately described by R. Hertwig (1879, _loc. cit._, p. 94, Taf. x. figs. 2, 4, 5, 8, 14). The large astropyle with its radiate operculum and proboscis, and the two smaller lateral parapylæ, provided with {1620}a smaller tubule, have in general the same shape as in the closely allied Sagosphærida and Orosphærida, and agree in their strong development with that of the Aulacanthida. The collection of the Challenger contains numerous well-preserved preparations of Aulosphærida, which were stained by carmine immediately after being captured, and in which the central capsule and its nucleus exhibit the same intimate structure already accurately described by R. Hertwig. The diameter of the capsule is usually between 0.2 and 0.3, rarely less than 0.15 or more than 0.35 mm., the nucleus has half that size. The phæodium has usually about the same volume (Pl. 109, fig. 1), but seems to be in many Aulosphærida less developed than in the other PHÆODARIA.

_Synopsis of the Genera of Aulosphærida._

------------------------------------------------------------------------- I. Subfamily Aularida. Meshes of the network triangular, regular or subregular. Six tangential tubes united at each nodal point of the net. ------------------------------------------------------------------------- { Without radial tubes, 682. _Aularia_. Shell spherical, with { a simple network. { With radial tubes in { the nodes of the net, 683. _Aulosphæra_.

{ Shell covered with pyramidal { elevations, the top of Shell spherical, with { which bears a radial tube, 684. _Auloscena_. pyramidal elevations { or with spongy { Shell with spongy framework, framework. { the surface of which bears { radial tubes, 685. _Auloplegma_.

{ Shell lenticular, with Shell not spherical, { shortened main axis and either lenticular or { radial tubes, 686. _Aulophacus_. spindle-shaped, with { simple network. { Shell spindle-shaped, with { prolonged main axis and { radial tubes, 687. _Aulatractus_. ------------------------------------------------------------------------- II. Subfamily Aulonida. Meshes of the network polygonal, usually irregular. Three or four (rarely more) tangential tubes united at each nodal point. ------------------------------------------------------------------------- { Without radial tubes, 688. _Aulonia_. Shell spherical, with { a simple network. { With radial tubes in the { nodes of the net, 689. _Aulastrum_.

Shell spherical, with { Without radial tubes, 690. _Aulodictyum_. a spongy framework. {

Subfamily 1. AULARIDA, Haeckel.

_Definition._--Network of the shell with triangular, regular or subregular meshes; six tangential tubes being united at each nodal point.

{1621}Genus 682. _Aularia_,[301] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form a simple smooth lattice-sphere. No radial tubes at the nodal points.

The genus _Aularia_ is the simplest form of the subfamily Aularida, or of those Aulosphærida in which the network of the shell is composed of regular or subregular triangular meshes; they are the main group of the family, much more common and far richer in distinct forms than the Aulonida (or the Aulosphærida with polygonal meshes). The shell of _Aularia_, the probable ancestral form of the family, is a simple lattice-sphere with smooth surface, and differs from the common _Aulosphæra_ in the absence of radial tubes, arising at the nodal points.

1. _Aularia ternaria_, n. sp. (Pl. 111, fig. 2).

Tangential tubes of the network cylindrical, straight, smooth, of equal breadth. Triangular meshes of the reticular sphere very regular, equilateral triangular. This species is the simplest of all Aulosphærida and similar to the common _Aulosphæra trigonopa_, but has no radial tubes.

_Dimensions._--Diameter of the sphere 1.0 to 2.0; tubes 0.1 to 0.15 long, 0.007 to 0.01 broad.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

2. _Aularia tubularia_, n. sp.

Tangential tubes of the network cylindrical, straight, of equal breadth, thorny, covered with numerous short bristle-shaped thorns, which are all of the same length and perpendicular to the tube.

_Dimensions._--Diameter of the sphere 3.0; tubes 0.15 long, 0.005 broad.

_Habitat._--South Pacific, Station 291, depth 2250 fathoms.

3. _Aularia trigonaria_, n. sp.

Tangential tubes of the network smooth, very thin in the middle part, gradually dilated towards both ends, so that the nodal points of the network are inflated. (Similar to _Aulosphæra sceptrophora_, Pl. 109, fig. 3, but without radial tubes.)

_Dimensions._--Diameter of the sphere 2.2; tubes 0.1 long, 0.002 broad in the middle part, 0.01 on both sides.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.

{1622}Genus 683. _Aulosphæra_,[302] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 802.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form a simple lattice-sphere. Radial tubes arise at its nodal points.

The genus _Aulosphæra_, the first observed form of all Aulosphærida, is also the most common form of the whole family, the richest in distinct species, and widely distributed over all oceans, in the tropical as well as in the temperate and Arctic zones.

The twenty-one species here enumerated may be only a small part of the numerous forms, which may be distinguished according to the different forms of the tubes. One of the two Mediterranean species, which I first described in my Monograph, is cosmopolitan. The shell is in all species a simple regular lattice-sphere with triangular meshes; it differs from the preceding _Aularia_ in the development of radial tubes at the nodal points of the lattice-work.

Subgenus 1. _Aulosphærantha_, Haeckel.

_Definition._--Radial tubes simple, smooth, without terminal teeth and without lateral branches.

1. _Aulosphæra trigonopa_, Haeckel.

_Aulosphæra trigonopa_, Haeckel, 1862, Monogr. d. Radiol., p. 359, Taf. x. fig. 4.

Radial tubes of the spherical shell cylindro-conical, straight, smooth, of the same length as the tangential tubes of the network, which are also smooth, straight, cylindrical.

_Dimensions._--Diameter of the sphere 1.0 to 2.0; tangential tubes 0.1 to 0.2 long, 0.002 to 0.004 broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

2. _Aulosphæra flexuosa_, n. sp.

Radial tubes slenderly conical, smooth, gradually tapering towards the distal end, more or less irregularly curved, two to three times as long as the tangential tubes, which are cylindrical, straight and smooth.

_Dimensions._--Diameter of the sphere 2.2; tangential tubes 0.15 long, 0.006 broad.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, surface.

{1623}Subgenus 2. _Aulosphærella_, Haeckel.

_Definition._--Radial tubes smooth, without lateral branches or spines, but armed with a verticil of teeth at the distal end.

3. _Aulosphæra diodon_, n. sp.

Radial tubes cylindro-conical, straight, smooth, of the same length as the smooth, cylindrical, tangential tubes; armed at the distal end with two divergent terminal teeth, which are slightly curved, pincer-shaped, and about one-fourth as long as the tube.

_Dimensions._--Diameter of the sphere 2.5; tangential tubes 0.16 long, 0.003 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

4. _Aulosphæra triodon_, n. sp. (Pl. 109, fig. 8).

Radial tubes cylindrical, straight, smooth, two to three times as long as the smooth, cylindrical, tangential tubes; armed at the distal end with three divergent terminal teeth, which are straight or slightly curved and about one-third as long as the tube.

_Dimensions._--Diameter of the sphere 1.2; tangential tubes 0.1 long, 0.01 broad.

_Habitat._--North-Eastern Pacific (off Japan), Station 231, surface.

5. _Aulosphæra tetrodon_, n. sp.

Radial tubes slender, cylindrical, straight, smooth, about three times as long as the smooth, cylindrical, tangential tubes; armed at the distal end with a regular cross of four terminal teeth, which are directed almost horizontally, and are slightly recurved (just as in _Aulosphæra spathillata_, Pl. 109, fig. 7, but longer and without lateral verticils).

_Dimensions._--Diameter of the sphere 1.6; tangential tubes 0.15 long, 0.005 broad.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

6. _Aulosphæra polyodon_, n. sp.

Radial tubes slender, spindle-shaped, gradually tapering towards the two ends, smooth, about twice as long as the cylindrical, smooth, tangential tubes; armed at the distal end with a verticil of twelve to twenty or more divergent, conical, slightly curved teeth.

_Dimensions._--Diameter of the sphere 3.3; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.

Subgenus 3. _Aulosphærissa_, Haeckel.

_Definition._--Radial tubes verticillate, armed with a variable number of regular verticils of lateral branches.

{1624}7. _Aulosphæra verticillata_, n. sp.

Radial tubes slender, cylindro-conical, straight, tapering towards the distal end, about as long as the smooth, cylindrical, tangential tubes; armed with eight to twelve verticils of three curved, simple, lateral branches. (Very similar to the tubes of _Aulastrum trichoceros_, Pl. 111, fig. 5_a._)

_Dimensions._--Diameter of the sphere 1.6; tangential tubes 0.15 long, 0.008 broad.

_Habitat._--South Pacific, Station 300, surface.

8. _Aulosphæra spathillata_, n. sp. (Pl. 109, figs. 7, 7_a_).

Radial tubes slender, cylindro-conical, straight, tapering towards the distal end, two to three times as long as the smooth, cylindrical, tangential tubes; armed with two or three distal alternate verticils, each of which forms a horizontal cross of four (sometimes three or five) equidistant branches; their distal ends are on the terminal cross simple hooks, on the proximal cross spathillæ.

_Dimensions._--Diameter of the sphere 3.2; tangential tubes 0.12 to 0.16 long, 0.01 broad.

_Habitat._--South-Eastern Pacific (off Valparaiso), Station 298, depth 2225 fathoms.

9. _Aulosphæra cruciata_, Haeckel (Pl. 109, fig. 10).

_Aulosphæra elegantissima_, R. Hertwig (_non_ Haeckel), 1879, Organism. d. Radiol., p. 90, Taf. ix. fig. 1; Taf. x. figs. 2, 4, 5, 8, 14, 15.

? _Aulosphæra pourtalesii_, Duncan, 1881, Journ. Roy. Micr. Soc., p. 175, pl. iii. figs. 1-3.

Radial tubes slender, cylindro-conical, straight, tapering towards the distal end, twice as long as the smooth, cylindrical, tangential tubes; armed with four to eight cruciate equidistant verticils, each of which forms a regular cross of four equal, horizontal, lateral branches, bearing at the end a small knob or spathilla.

_Dimensions._--Diameter of the sphere 1.2 to 1.8; tangential tubes 0.1 to 0.15 long, 0.003 broad.

_Habitat._--Mediterranean (Messina), North Atlantic (Canary Islands), Caribbean Sea.

10. _Aulosphæra elegantissima_, Haeckel.

_Aulosphæra elegantissima_, Haeckel, 1862, Monogr. d. Radiol., p. 359, Taf. x. fig. 5; Taf. xi. figs. 5, 6.

Radial tubes cylindrical, straight, twice as long as the smooth, cylindrical, tangential tubes; armed with four to eight equidistant verticils, each of which is composed of eight to twelve simple, horizontal, lateral branches.

_Dimensions._--Diameter of the sphere 1.5 to 2; tangential tubes 0.12 to 0.16 long, 0.004 broad.

_Habitat._--Mediterranean (Messina), surface.

11. _Aulosphæra bisternaria_, n. sp. (Pl. 109, figs. 11, 12).

Radial tubes cylindrical, straight, about as long as the cylindrical tangential tubes, smooth or somewhat thorny, armed at the distal end with two alternate verticils of three branches, which bear {1625}a terminal spathilla; the proximal branches are twice as long as the distal, and alternate with them regularly, so that the six branches lie in six different meridional planes.

_Dimensions._--Diameter of the sphere 2.5; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--Antarctic Ocean, Station 156, surface.

12. _Aulosphæra dendrophora_, n. sp. (Pl. 109, figs. 1, 2).

Radial tubes cylindrical, straight, about as long as the cylindrical, smooth, tangential tubes, armed in the distal half with three verticils of four crossed branches; the four proximal branches are three times as long as the four distal, and twice as long as the four intermediate branches. All twelve branches bear a terminal spinulate knob, and lie in two perpendicularly crossed meridian planes.

_Dimensions._--Diameter of the sphere 2.2 to 2.8; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

13. _Aulosphæra sceptrophora_, n. sp. (Pl. 109, figs. 3, 4).

Radial tubes straight, in the proximal half conical, with inflated base; in the distal half cylindrical, with five or six cruciate verticils, each of which has four perpendicularly crossed teeth. Tangential tubes half as long as the radial tubes, in the middle part very thin, thickened towards both ends.

_Dimensions._--Diameter of the sphere 1.2; tangential tubes 0.1 long, 0.002 broad in the middle part, 0.012 on both ends.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.

14. _Aulosphæra spathophora_, n. sp.

Radial tubes slender, cylindrical, more or less curved, about three times as long as the tangential tubes, in the distal half with eight to twelve verticils of six to eight lateral branches, which are forked, decrease in length towards the distal end, and bear on each ramule a terminal spathilla. Tangential tubes slightly curved and thorny. (Similar to _Auloplegma perplexum_, Pl. 111, fig. 8_a_, but with a simple lattice-sphere.)

_Dimensions._--Diameter of the sphere 2.2; tangential tubes 0.2 long. 0.006 broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

Subgenus 4. _Aulosphæromma_, Haeckel.

_Definition._--Radial tubes spiny or thorny, with irregular lateral branches, often with forked distal ends.

{1626}15. _Aulosphæra bifurca_, n. sp.

Radial tubes cylindrical, straight, thorny, twice as long as the smooth, cylindrical, tangential tubes, forked at the distal end, with two curved, convergent, thorny, terminal branches. (Similar to _Aulastrum dendroceros_, Pl. 111, figs. 4_a_-4_c_, but with longer and more spinulate branches.)

_Dimensions._--Diameter of the sphere 3.2; tangential tubes 0.25 long, 0.01 broad.

_Habitat._--North Pacific, Station 239, surface.

16. _Aulosphæra trifurca_, n. sp. (Pl. 109, fig. 9).

Radial tubes cylindrical, straight, thorny, about as long as the smooth, cylindrical, tangential tubes, forked at the distal end, with three curved, convergent, terminal branches.

_Dimensions._--Diameter of the sphere 2.5 to 3.0; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--North Pacific, Station 240, surface.

17. _Aulosphæra quadrifurca_, n. sp.

Radial tubes cylindro-conical, straight, about as long as the smooth, cylindrical, tangential tubes; studded with numerous irregular lateral branches in the distal half, and armed at the distal end with a cross of four divergent, forked, terminal branches.

_Dimensions._--Diameter of the sphere 4.2; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

18. _Aulosphæra multifurca_, n. sp.

Radial tubes cylindrical, more or less curved, three to four times as long as the smooth, often curved, tangential tubes; studded with numerous forked, irregular, lateral branches, and armed at the distal end with a verticil of twelve to sixteen divergent, forked, terminal branches.

_Dimensions._--Diameter of the sphere 1.2; tangential tubes 0.06 long, 0.003 broad.

_Habitat._--Arctic Ocean, Greenland (Olrik), surface.

19. _Aulosphæra coronata_, n. sp.

Radial tubes spindle-shaped, tapering from the thicker middle part towards both ends, twice as long as the thorny tangential tubes, studded with numerous irregular, curved, lateral spines, and bearing at the distal end a corona of twenty to twenty-five divergent, curved, terminal branches. (Similar to _Auloscena flammabunda_, Pl. 110, fig. 4.)

_Dimensions._--Diameter of the sphere 3.0; tangential tubes 0.2 long, 0.08 broad.

_Habitat._--Tropical Atlantic, Station 347, surface.

{1627}20. _Aulosphæra undulata_, n. sp. (Pl. 109, fig. 6).

Radial tubes slender, cylindro-conical, undulate, about twice as long as the spinulate and undulate tangential tubes; studded with numerous short, perpendicular, lateral branches which are partly simple, partly forked, and bear small terminal spathillæ. The distal end of each radial tube bears usually a verticil of four to eight similar pediculate spathillæ.

_Dimensions._--Diameter of the sphere 2.4; tangential tubes 0.2 long, 0.005 broad.

_Habitat._--North Pacific, Station 252, surface.

21. _Aulosphæra spinosa_, n. sp. (Pl. 109, fig. 5).

Radial tubes and tangential tubes equal in size and similar in form, more or less curved, slender, cylindrical, densely studded with numerous irregular spines.

_Dimensions._--Diameter of the sphere 1.6; tangential tubes 0.1 long, 0.004 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

Genus 684. _Auloscena_,[303] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which arise in pyramidal groups of six over the surface of the spherical shell. Radial tubes arise at the tops of the six-sided pyramids, which cover the whole surface.

The genus _Auloscena_ differs from the preceding _Aulosphæra_, its ancestral form, in a very remarkable and elegant character. The tangential tubes of the network here lie not on a spherical face (as in the latter), but arise over the surface of the spherical calymma in the form of numerous, regular, hexagonal pyramids; each pyramid being composed of six convergent ascending tubes, which are united in a common nodal point; at the latter arises a radial tube, which usually bears an elegant corona of radially divergent terminal branches. Therefore the base of each hexagonal pyramid is in contact at its six corners with the basal corners of six similar neighbouring pyramids, whilst the neighbouring sides of the bases are separated by six regular triangular meshes, which lie on the spherical face. In some species this remarkable and elegant structure is quite regular, whilst in others it becomes more or less irregular.

Subgenus 1. _Auloscenium_, Haeckel.

_Definition._--Radial tubes smooth, without lateral branches or spines, bearing a terminal verticil at the distal end.

{1628}1. _Auloscena mirabilis_, n. sp. (Pl. 110, figs. 1, 2).

Radial tubes cylindrical, straight, smooth, about as long as the smooth pyramidal tubes (or the convergent tubes which form the edges of the six-sided pyramids of the network). The distal end of each radial tube bears an elegant spathillate terminal corona (fig. 2), or a verticil of fifteen to twenty curved radial branches, the distal end of which is armed with a spinulate knob.

_Dimensions._--Diameter of the sphere 2.0 to 3.0; pyramidal tubes 0.16 to 0.24 long, 0.008 broad.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

2. _Auloscena spectabilis_, n. sp. (Pl. 110, figs. 8, 9).

Radial tubes cylindro-conical, straight, smooth, twice as long as the smooth pyramidal tubes, armed at the distal end with a conical terminal corona, or a verticil of twelve to sixteen divergent, straight, pointed, terminal branches.

_Dimensions._--Diameter of the sphere 4.0 to 5.0; pyramidal tubes 0.25 to 0.3 long, 0.012 broad.

_Habitat._--Antarctic Ocean, Station 154, surface.

3. _Auloscena pyramidalis_, n. sp.

Radial tubes slender, conical, straight, smooth, of the same length as the smooth pyramidal tubes, armed at the distal end with a hexagonal terminal corona, or a verticil of six divergent, straight, pointed, terminal branches, which correspond to the six sides of a pyramid; the proximal apex of this terminal pyramid is opposed to the distal apex of the similar basal pyramid.

_Dimensions._--Diameter of the sphere 3.0 to 4.0; pyramidal tubes 0.2 to 0.3 long, 0.01 broad.

_Habitat._--Tropical Atlantic, Stations 347 to 349, surface.

Subgenus 2. _Auloscenidium_, Haeckel.

_Definition._--Radial tubes thorny, with lateral branches or spines, usually with a terminal verticil at the distal end.

4. _Auloscena tentorium_, n. sp. (Pl. 110, fig. 6).

Radial tubes spindle-shaped, tapering towards both ends, nearly smooth, of the same length as the smooth pyramidal tubes. The distal part of the radial tubes is thorny, and bears a verticil or a corona of twenty to thirty slender terminal branches, which are about one-third as long as the tube, sabre-shaped, with concave outer edge and pointed distal end.

_Dimensions._--Diameter of the sphere 4.0; radial tubes 0.3 to 0.4 long, 0.02 to 0.03 broad.

_Habitat._--North-Western Pacific (off Japan), Station 231, surface.

{1629}5. _Auloscena verticillus_, n. sp. (Pl. 110, figs. 10, 11).

Radial tubes slender, cylindrical, twice as long as the smooth or somewhat thorny pyramidal tubes, armed in the distal part with two or three irregular verticils of three to six perpendicular spines, and on the distal end with a corona of twelve to eighteen straight, divergent, pointed, terminal branches, which often arise in pairs.

_Dimensions._--Diameter of the sphere 3.2; pyramidal tubes 0.15 long, 0.01 broad.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

6. _Auloscena penicillus_, n. sp. (Pl. 110, fig. 3).

Radial tubes slender, cylindrical, thorny, one and a half times as long as the thin and smooth pyramidal tubes, armed in the distal half with densely crowded perpendicular spines and a terminal corona of numerous (twenty to thirty or more) bristle-shaped branches, like a brush.

_Dimensions._--Diameter of the sphere 2.0 to 2.5; radial tubes 0.15 to 0.2 long, 0.005 to 0.01 broad.

_Habitat._--Antarctic Ocean, Stations 156, 157, surface.

7. _Auloscena flammabunda_, n. sp. (Pl. 110, fig. 4).

Radial tubes cylindro-conical, twice as long as the thorny pyramidal tubes, studded with numerous curved spines, and armed with a verticil or corona of numerous (twenty to thirty or more) undulate, divergent, pointed, terminal branches.

_Dimensions._--Diameter of the sphere 3.0; radial tubes 0.3 to 0.4 long, 0.02 to 0.03 broad.

_Habitat._--North Pacific, Station 252, surface.

8. _Auloscena gigantea_, n. sp. (Pl. 110, fig. 7).

Radial tubes cylindrical, thorny, about as long as the thorny pyramidal tubes, armed in the distal half with four to eight verticils of short curved ciliæ, and at the distal end with a similar small terminal verticil.

_Dimensions._--Diameter of the sphere 5.2; pyramidal tubes 0.2 to 0.3 long, 0.01 broad.

_Habitat._--Central Pacific, Stations 265 to 268, surface.

9. _Auloscena arboretum_, n. sp.

Radial tubes cylindrical, straight or slightly curved, about the same length as the smooth pyramidal tubes; armed in the distal half with three or four verticils, tapering in size towards the distal end; each verticil is composed of four crossed and curved branches, which bear a terminal spinulate knob. (This species is very similar to _Aulosphæra dendrophora_, Pl. 109, fig. 1, and may {1630}be derived from it by elevation of the hexagonal pyramids, which in the latter lie in the spherical plane).

_Dimensions._--Diameter of the sphere 4.4; pyramidal tubes 0.25 long, 0.01 broad.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.

10. _Auloscena serrata_, n. sp. (Pl. 110, fig. 5).

Radial tubes spindle-shaped, tapering towards both ends, thorny, twice as long as the thorny pyramidal tubes; armed at the distal end with an elegant corona which is composed of twelve to sixteen curved terminal branches. Each branch bears two opposite series of small recurved teeth and a terminal spathilla of six to eight larger recurved teeth.

_Dimensions._--Diameter of the sphere 3.0; pyramidal tubes 0.3 long, 0.012 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.

Genus 685. _Auloplegma_,[304] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tubes of which are connected in different directions, and form the spongy wall of a spherical shell. Radial tubes arise on the surface at the nodal points.

The genus _Auloplegma_, one of the rarest forms of Aulosphærida, differs from the preceding genera in the spongy structure of the lattice-sphere, the thickened wall of which is composed of a loose framework. Numerous tubes, irregularly disposed in different directions, are connected at the nodal points of this loose spongy framework, whilst radial tubes arise on the surface of the latter. _Auloplegma_ exhibits therefore a relation to _Aulosphæra_, its probable ancestral form, similar to that which _Plegmosphæra_ does to _Acanthosphæra_ among the #Sphæroidea#.

1. _Auloplegma perplexum_, n. sp. (Pl. 111, figs. 8, 8_a_).

Radial tubes straight, cylindro-conical, armed with six to eight verticils of lateral branches, which increase in size towards the base; each verticil is a cross of four dichotomous delicate ramules, ending with a spinulate knob. The length of the radial tube is about equal to the radial diameter of the spongy framework, which forms the thick wall of the spherical shell, and is composed of smooth and straight cylindrical tubes.

_Dimensions._--Diameter of the shell 1.5 to 2.0, of its wall 0.3 to 0.4; length of the radial tubes 0.2 to 0.3, basal breadth 0.015.

_Habitat._--North Pacific, Station 237, surface.

{1631}2. _Auloplegma spongiosum_, n. sp. (Pl. 111, fig. 9).

Radial tubes slender, straight, cylindro-conical, studded irregularly with lateral branches, which are short, simple, slightly curved, partly verticillate in the distal third, and ending with a small spinulate knob. The length of the radial tubes is about twice as great as the radial diameter of the spongy framework, which forms the wall of the spherical shell, and is composed of thorny or verticillate cylindrical tubes.

_Dimensions._--Diameter of the shell 3.2, of its wall 0.1; length of the radial tubes 0.24, breadth 0.01.

_Habitat._--North Pacific, Station 231, surface.

Genus 686. _Aulophacus_,[305] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form a simple, lenticular, biconvex lattice-shell, with shortened vertical main axis. Radial tubes arise at its nodal points.

The genus _Aulophacus_ differs from the common _Aulosphæra_, its ancestral form, only in the lenticular compression of the spherical lattice-shell, the vertical axis of which is considerably shortened. It exhibits therefore to the latter the same relation as _Cenodiscus_ does to _Cenosphæra_ among the #Sphæroidea#. The contrary condition is shown in the following genus _Aulatractus_, in which the vertical axis is prolonged. In the two species of _Aulophacus_ observed the radial spines exhibit a remarkable peculiarity, being longer on the circular periphery of the lens, shorter on both its faces, and shortest in the vertical main axis.

1. _Aulophacus lenticularis_, n. sp. (Pl. 111, fig. 5_a_).

Shell biconvex, lenticular, with rounded circular margin; its horizontal diameter three times as great as its thickness (or its vertical main axis). Radial tubes cylindro-conical, straight, with six to nine triradiate verticils, those of the margin of the lens twice as long as the smooth tangential tubes, the others shorter.

_Dimensions._--Horizontal diameter of the lens 5.5 mm., vertical main axis 0.2; length of the radial tubes 0.2, breadth 0.01.

_Habitat._--Indian Ocean, Belligemma, Ceylon (Haeckel), surface.

2. _Aulophacus amphidiscus_, n. sp. (Pl. 111, fig. 5_b_).

Shell discoidal, slightly biconvex, with rounded circular margin; its horizontal diameter five times as great as its thickness. Radial tubes cylindrical, covered with numerous short thorns, those of the margin of the lens three times as long as the smooth tangential tubes, the others shorter.

{1632}_Dimensions._--Horizontal diameter of the lens 6.0, vertical main axis 1.2; length of the radial tubes 0.2, breadth 0.005.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

Genus 687. _Aulatractus_,[306] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form an ellipsoidal or spindle-shaped, simple lattice-shell, with prolonged vertical main axis. Radial tubes arise at its nodal points.

The genus _Aulatractus_ differs from all the other Aulosphærida in the peculiar prolongation of the vertical axis of the lattice-sphere, by which the latter becomes ellipsoidal or spindle-shaped. The triangular meshes of the regular lattice-work become usually more or less irregular and polygonal at the two poles of the elongated main axis. _Aulatractus_ seems to be developed from _Aulosphæra_ in the opposite way from _Aulophacus_, the former by elongating, the latter by shortening of the vertical main-axis.

1. _Aulatractus fusiformis_, n. sp. (Pl. 111, figs. 6, 6_a_, 6_b_).

Shell spindle-shaped, about twice as long as broad, rounded at both poles of the main axis. Tangential tubes smooth, cylindrical. Radial tubes of the same length as the tangential tubes, but much thinner, slender cylindrical, studded with perpendicularly arising, short, lateral branches, which are scattered in the proximal part, verticillate in the distal part, and bear a spinulate terminal knob.

_Dimensions._--Length of the shell 7.5 to 10.0, breadth 3.5; length of the radial tubes 0.15 to 0.18, breadth 0.004.

_Habitat._--Tropical Atlantic, Stations 348, 349; surface, and in various depths.

2. _Aulatractus diploconus_, n. sp. (Pl. 111, fig. 7).

Shell diploconical or nearly spindle-shaped, about three times as long as broad, equally pointed at the two poles of the main axis, not inflated in the middle part. Radial tubes slenderly conical, thorny, only half as long as the smooth tangential tubes.

_Dimensions._--Length of the shell 6.0 to 8.0, breadth 2.2 to 4.5; length of the radial tubes 0.1 to 0.15, breadth 0.007.

_Habitat._--North Atlantic, Canary Islands, Station 353, surface.

3. _Aulatractus fusulus_, n. sp.

Shell spindle-shaped, about twice as long as broad, pointed at the two equal poles of the main axis. Radial tubes cylindro-conical, smooth, about as long as the smooth tangential tubes. This {1633}species resembles in its simple structure the common cosmopolitan _Aulosphæra trigonopa_, and differs from it only in the constant spindle-form of the shell.

_Dimensions._--Length of the shell 6 to 8, breadth 3 to 4; length of the radial tubes 0.16 to 0.2, breadth 0.008.

_Habitat._--North Atlantic, Færöe Channel, Gulf Stream (John Murray); Hebrides (Moebius).

4. _Aulatractus ellipsoides_, n. sp.

Shell ellipsoidal, about twice as long as broad, with equally rounded poles on the main axis. Radial tubes straight, cylindrical, verticillate, about twice as long as the smooth tangential bars; each verticil is cruciate, composed of four rectangularly crossed, short, lateral branches which bear a small spathilla at the distal end.

_Dimensions._--Length of the shell 6.6, breadth 3.6; length of the radial tubes 0.2, breadth 0.01.

_Habitat._--South Atlantic, Station 332, surface.

Subfamily 2. AULONIDA, Haeckel.

_Definition._--Network of the shell with polygonal, usually irregular meshes; three or four tangential tubes usually being united at each nodal point.

Genus 688. _Aulonia_,[307] n. gen.

_Definition._--#Aulosphærida# with polygonal meshes in the network, the tangential tubes of which form a simple smooth lattice-sphere. No radial tubes at the nodal points.

The genus _Aulonia_ is the simplest form of the subfamily Aulonida, or of those Aulosphærida in which the lattice-work of the shell is composed not of triangular but of polygonal meshes; all these Aulonida are much rarer and much less differentiated than the Aularida or the common Aulosphærida with triangular meshes. _Aulonia_ has the same simple, smooth, spherical lattice-shell as _Aularia_, and differs from it only in the polygonal form of the meshes, which, however, is very constant.

1. _Aulonia tetragonia_, n. sp.

Meshes regular or subregular, square, sometimes intermingled with a variable number of irregular, triangular, and pentagonal meshes. Bars cylindrical, of equal breadth.

_Dimensions._--Diameter of the spherical shell 2.0 to 3.2, of the meshes 0.12 to 0.18; breadth of the bars 0.008.

_Habitat._--Antarctic Ocean, Station 154, depth 1800 fathoms.

{1634}2. _Aulonia pentagonia_, n. sp.

Meshes subregular, pentagonal, intermingled with a smaller number of quadrangular and triangular irregular meshes. Bars cylindrical, of equal breadth.

_Dimensions._--Diameter of the spherical shell 2.8 to 3.2, of the meshes 0.15 to 0.2; breadth of the bars 0.01.

_Habitat._--South Pacific, Stations 293 to 302, depth 1375 to 2270 fathoms.

3. _Aulonia hexagonia_, n. sp. (Pl. 111, fig. 1).

Meshes regular or subregular, hexagonal, often intermingled with a variable number of pentagonal and heptagonal meshes. Bars cylindrical, of equal breadth.

_Dimensions._--Diameter of the spherical shell 2.5 to 3.3, of the meshes 0.15 to 0.25; breadth of the bars 0.012.

_Habitat._--Tropical Atlantic, Stations 347 to 349, surface.

4. _Aulonia metagonia_, n. sp.

Meshes subregularly alternating, larger octagonal and smaller tetragonal. The network of this remarkable species has a striking similarity to the arrangement of the radial tubes in some species of _Sycon_, figured in my Monograph of the Calcispongiæ (1872, Bd. iii., Taf. ix. fig. 12).

_Dimensions._--Diameter of the sphere 4.4, of the greater octagonal meshes 0.24 to 0.3, smaller tetragonal 0.1 to 0.12; breadth of the bars 0.007.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.

5. _Aulonia polygonia_, n. sp.

Meshes irregular, polygonal, variable in form and unequal in size; the majority usually pentagonal or hexagonal, but numerous intermingled meshes with three, four, seven, or eight sides. Very variable in the size of the bars and the form of the meshes.

_Dimensions._--Diameter of the sphere 2.5 to 5.5, of the meshes 0.1 to 0.2; breadth of the bars 0.008 to 0.12.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface.

Genus 689. _Aulastrum_,[308] n. gen.

_Definition._--#Aulosphærida# with polygonal meshes in the network, the tangential tubes of which form a simple lattice-sphere. Radial tubes arise at its nodal points.

{1635}The genus _Aulastrum_ differs from the preceding _Aulonia_, its ancestral form, only in the development of radial spines at the nodal points of the simple lattice-sphere. It exhibits therefore to the latter the same relation as _Aulosphæra_ does to _Aularia_. But the meshes of the spherical network are constantly triangular in the two latter genera, polygonal in the two former. The different species of _Aulastrum_ are much rarer, and are not so differentiated as those of the common _Aulosphæra_.

1. _Aulastrum monoceros_, n. sp.

Radial tubes simple, smooth, straight, cylindro-conical, about as long as the smooth tangential tubes or somewhat longer. Meshes of the network irregularly polygonal, the majority usually pentagonal or hexagonal.

_Dimensions._--Diameter of the sphere 3.0 to 4.0, of the meshes 0.15; breadth of the tubes 0.012.

_Habitat._--Tropical Atlantic, Stations 347, 348, depth 2250 to 2450 fathoms.

2. _Aulastrum dichoceros_, n. sp.

Radial tubes cylindrical, more or less curved, undulate, smooth, twice as long as the smooth tangential tubes, forked at the distal end, with two divergent curved branches. Meshes of the network subregular, hexagonal (as in _Aulonia hexagonia_, Pl. 111, fig. 1), intermingled with single pentagonal and square meshes.

_Dimensions._--Diameter of the sphere 2.0 to 2.5, of the meshes 0.12 to 0.18; breadth of the tubes 0.01.

_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.

3. _Aulastrum dendroceros_, n. sp. (Pl. 111, figs. 4_a_, _b_, _c_).

Radial tubes cylindrical, straight or slightly curved, thorny, forked at the distal end, two to three times as long as the thorny tangential tubes; the thorns are short and thin, partly simple, partly irregularly branched and scattered, arborescent. Meshes of the network irregularly polygonal, the majority pentagonal or tetragonal.

_Dimensions._--Diameter of the sphere 2.4; radial tubes 0.2 to 0.3 long, 0.02 broad.

_Habitat._--North Pacific, Station 241 to 244, surface.

4. _Aulastrum triceros_, n. sp. (Pl. 111, figs. 3, 3_a_).

Radial tubes cylindrical, straight, smooth, about twice as long as the smooth tangential tubes, armed with three divergent curved teeth at the distal end. Meshes subregular, pentagonal, intermingled with a small number of tetragonal and hexagonal meshes.

_Dimensions._--Diameter of the sphere 1.2 to 1.8; radial tubes 0.15 long, 0.01 broad.

_Habitat._--Tropical Atlantic, Station 349, depth 2450 fathoms.

{1636}5. _Aulastrum trichoceros_, n. sp.

Radial tubes slender, straight, cylindro-conical, about twice as long as the smooth tangential tubes, armed with six to eight verticils of lateral branches, each of which is composed of three short curved branches (similar to those of _Aulophacus lenticularis_, Pl. 111, fig. 5_a_). Meshes irregularly polygonal, the majority tetragonal, intermingled with pentagonal and triangular meshes.

_Dimensions._--Diameter of the sphere 2.2; tangential tubes 0.12 long, 0.007 broad.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

6. _Aulastrum tetraceros_, n. sp.

Radial tubes straight, cylindrical, about three times as long as the smooth tangential meshes, armed with three to six subregular cruciate verticils of branches, each of which is composed of four short, regularly crossed branches, bearing at the end a spinulate knob (similar to those of _Aulatractus fusiformis_, Pl. 111, fig, 6_b_). Meshes subregular, square, intermingled with single pentagonal and hexagonal meshes.

_Dimensions._--Diameter of the sphere 1.5, of the meshes 0.12 to 0.16; breadth of the bars 0.008.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

7. _Aulastrum pentaceros_, n. sp.

Radial tubes straight, cylindrical, smooth, about as long as the smooth tangential tubes, armed at the distal end with a corona of five curved teeth (of the same shape as in _Cannosphæra atlantica_, Pl. 112, fig. 6). Meshes subregular pentagonal (intermingled with single tetragonal, hexagonal, and heptagonal meshes).

_Dimensions._--Diameter of the sphere 5.0, of the meshes 0.2; breadth of the bars 0.015.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

8. _Aulastrum polyceros_, n. sp.

Radial tubes spindle-shaped, tapering from the broader middle towards both ends, spiny, twice as long as the spiny tangential tubes, armed at the distal end with a corona of twelve to twenty divergent curved teeth (similar to the radial tubes of _Auloscena tentorium_, Pl. 110, fig. 6). Meshes irregular, polygonal, very variable in size and form. All tubes of this species are armed with scattered, short, conical spines.

_Dimensions._--Diameter of the sphere 4.5, of the meshes 0.1 to 0.2; breadth of the bars 0.006.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

{1637}Genus 690. _Aulodictyum_,[309] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Aulosphærida# with polygonal meshes in the network, the tubes of which are connected in different directions and form the spongy wall of a spherical shell. No radial tubes prominent over the surface.

The genus _Aulodictyum_ differs from _Aulonia_, its ancestral form, in the development of a spongy framework in the thickened wall of the spherical lattice-shell. It bears therefore to the latter the same relation as _Auloplegma_ does to _Aularia_. But the outer surface of the hollow sphere is in _Aulodictyum_ completely smooth, as well as the inner, and bears no radial tubes. Only one species of this genus has been observed.

1. _Aulodictyum hydrodictyum_, n. sp.

Shell spherical, smooth on the outer and inner surfaces, composed of an irregular framework of straight and smooth cylindrical tubes; its meshes very irregular, of unequal size and various forms. The diameter of the sphere is about six or eight times as great as the thickness of its reticular wall.

_Dimensions._--Diameter of the sphere 2 to 3, of its meshes 0.1 to 0.2; breadth of the bars 0.01.

_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.

Family LXXVII. #CANNOSPHÆRIDA#, Haeckel (Pl. 112).

_Cannosphærida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--PHÆODARIA with two concentric spherical or subspherical shells, which are connected by numerous thin, tubular, radial beams. Inner shell simple, spherical or ovate, solid or latticed, with a peculiar mouth. Outer shell spherical or polyhedral, articulate, composed of hollow tangential tubes, which are separated by astral septa at the stellate nodal points. From the latter arise hollow radial tubes, whilst the inner radial beams, connecting the two shells, are inserted in the middle of the tangential tubes. No peculiar mouth in the outer shell. Central capsule enclosed by the inner shell.

The family #Cannosphærida# comprises a small number of remarkable PHÆODARIA which are rare and found only in a few localities. They differ from all the other PHÆODARIA in the possession of two concentric spherical shells, which are connected by radial beams, and the inner of which is quite simple, like that of the Medusettida, {1638}whilst the outer is articulated and composed of hollow tangential tubes, like that of the Aulosphærida. This latter family seems to be most nearly allied to the Cannosphærida, and is perhaps derived from them by loss of the inner shell. The possession of a peculiar mouth in this inner shell brings the Cannosphærida nearer to the Phæogromia. The similar Coelodrymida, in which also two concentric spherical shells are connected by hollow radial beams, differ essentially in the bivalved shape of the inner shell and the simple, non-articulated, network of the outer shell.

Only a single species of Cannosphærida has been hitherto known, described and figured in 1879 by R. Hertwig as _Coelacantha anchorata_ (_loc. cit._, p. 92, Taf. ix. fig. 2). The rich collection of the Challenger has added to it only four other species, one of which is most nearly allied to the former, whilst the others belong to a separate genus, _Cannosphæra_ (Pl. 112). The inner shell is in this latter genus a solid lamella of silica, whilst in the former it is fenestrated. In all other essential points of structure both genera are scarcely different.

The inner shell is either spherical or ovate and has a diameter of 0.1 to 0.4 (usually 0.2 to 0.3 mm.). A distinct main axis is always marked by the large open mouth on its oral pole. The aboral part of the shell-cavity contains the spherical central capsule, the oral part the dark phæodium, a part of which is often prominent through the mouth (figs. 1, 2, 4). The wall of the inner shell is a very thin and transparent lamella of silica, which is structureless and solid in _Cannosphæra_, distinctly fenestrated in _Coelacantha_; the pores of the latter are irregularly rounded and seem to possess a thickened margin.

From the surface of the inner shell arise numerous thin tubular, radial beams (twenty to eighty or more) and connect it with the outer shell. These beams are always very thin and straight cylindrical tubules, about twice to four times as long as the diameter of the inner shell, and usually 0.001 mm. broad, or even less. Their basal end at the surface of the latter appears mammillated (figs. 2, 4). The cavity of the inner shell seems to pass over immediately into the tubular cavities of the radial beams. These latter are sometimes simple, at other times articulated or jointed by a number of transverse septa. The radial beams are covered in all the species observed either with scattered spines (fig. 5) or with verticils of anchor-threads, very thin, filiform, lateral branches which bear a spathilla with three or four recurved teeth on the distal end (figs. 2, 4).

The outer shell is either spherical or an endospherical polyhedron, the prominent nodal points of which fall into a spherical face. Its diameter is usually from 2 to 3 mm., rarely more than 3 or less than 1 mm. Its structure is the same as described for the Aulosphærida, being composed of hollow cylindrical tubes, which form a loose network and are separated at its nodal points by astral septa. The meshes of the network are {1639}very large, usually twice to three times as broad as the inner shell, and irregularly polygonal; the usual and prevailing form is pentagonal, but hexagonal meshes are also often intermingled, more rarely meshes with five, seven, or eight sides.

The cylindrical tangential tubes possess in general the same shape as in the similar Aulosphærida, have a thin wall, are filled with jelly, and contain a delicate axial filament in their axis; they differ, however, in a peculiar constant character; in the middle of each tube is inserted an inner radial beam coming from the inner shell, so that both together have the form of a T. The central point of insertion has a somewhat shorter radial distance from the centre of the body than the two nodal points on both ends of the tangential tube, so that the latter is somewhat geniculate (figs. 1-5). The two halves of each tangential tube are usually somewhat thinner on the central end (where the inner radial beam is inserted), thicker on the distal end (where the outer radial tube arises); at both ends they are closed by a thin transverse septum. Often also some other septa are developed, so that each tangential tube seems to be composed of four to six joints or segments. Usually the tangential tubes are armed with spines or anchor threads, similar to those of the inner radial beams. The length of the single tangential tubes is usually between 0.1 and 0.3, their diameter from 0.01 to 0.02.

The nodal points of the outer lattice-sphere, in which the outer radial spines arise, seem to possess the same structure as in the similar Aulosphærida. Since three tangential tubes are connected to each nodal point, in its centre is the union of three small astral septa or sutural partitions. The small nodal cavity on the inside of the nodal point has probably three small pores, which lead into the three tangential tubes between the three astral septa. A fourth pore probably leads from the nodal cavity into the cavity of the hollow radial tube. This structure is difficult to observe, but seems to be demonstrated by the fact, that in the complete and carefully purified skeletons which are treated with hot mineral acids and afterwards dried, all cylinders, the tangential as well as the radial tubes, become easily filled by air (compare the description of the similar structure in the Aulosphærida).

The external radial tubes which arise in the nodal points of the outer shell are either cylindrical or cylindro-conical, straight, and usually about as long as the diameter of the inner shell. Their structure and armature is the same as in the similar Aulosphærida. In the axis of each radial tube runs a delicate axial filament, which is connected with its thin and fragile wall either by filiform transverse branches or by delicate transverse septa. The outside of the radial tubes is either smooth (figs. 3-5) or armed with scattered spines (fig. 4) or with verticils of lateral branches; each verticil is usually composed of three or four branches. The distal end of the radial tubes is rarely simple, pointed; it is usually armed with a spathilla of three or four curved terminal branches (figs. 3, 5) sometimes with an elegant corona composed of twenty to thirty thin radially divergent branches (fig. 4).

{1640}The _central capsule_ of the Cannosphærida is small (of 0.1 to 0.15 in diameter) and hidden in the aboral half of the enclosing inner shell, whilst the oral half of the latter is filled up by the phæodium (figs. 2, 4). The structure of the capsule and of its three openings seems to be the same as in the closely allied Aulosphærida. I have, however, not been able to recognise the two parapylæ or secondary openings, and have only observed the astropyle or the main-opening with its radiate operculum surrounded by the phæodium, and directed with its tubular proboscis towards the mouth of the inner shell. As R. Hertwig also could not recognise the two parapylæ, it is not impossible that they are wanting, and that the Cannosphærida possess only one opening, the astropyle, like the Medusettida and Challengerida. The nucleus, enclosed in the central capsule, is spherical, half or one-third as broad as the latter, and contains numerous nucleoli.

_Synopsis of the Genera of Cannosphærida._

Internal shell solid, without open pores, 691. _Cannosphæra_. Internal shell latticed, with open pores, 692. _Coelacantha_.

Genus 691. _Cannosphæra_,[310] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Cannosphærida# with a solid, not latticed internal shell.

The genus _Cannosphæra_ comprises those Cannosphærida in which the inner shell is formed by a thin solid siliceous-plate and exhibits no pores between the prominent bases of the radial beams.

1. _Cannosphæra atlantica_, n. sp. (Pl. 112, figs. 5, 6).

Internal shell not mammillate, with fifteen to twenty radial rods, which are loosely studded with single, scattered, simple, lateral spines. External shell with irregular, mostly hexagonal meshes, armed with numerous scattered forks of paired divergent spines, and with twenty to thirty larger simple radial spines, which are about half as long as the internal rods, and bear at the distal end a verticil of three to five curved, simple, terminal branches.

_Dimensions._--Diameter of the inner shell 0.1, of the outer 0.5.

_Habitat._--Tropical Atlantic, Stations 347 to 349, depth 2250 to 2450 fathoms.

2. _Cannosphæra antarctica_, n. sp. (Pl. 112, figs. 1-3).

Internal shell mammillate, with sixty to ninety radial rods, which are studded with cruciate verticils of tridentate anchor-threads. External shell with irregular, mostly pentagonal meshes, {1641}the bars of which bear on the outside bunches of similar tridentate anchor-threads. At each nodal point arises a simple, smooth, radial spine, which bears at the distal end a verticil of three or four small, curved, terminal branches.

_Dimensions._--Diameter of the inner shell 0.2 to 0.3, of the outer 1.5 to 2.0.

_Habitat._--Antarctic Ocean, Stations 154 to 157, depth 1300 to 1975 fathoms.

3. _Cannosphæra pacifica_, n. sp. (Pl. 112, fig. 4).

Internal shell mammillate, with one hundred to one hundred and twenty radial rods, which are studded with cruciate verticils of tridentate anchor-threads. External shell with irregular, mostly hexagonal meshes, the bars of which bear on the outside and on the inside bunches of similar tridentate anchor-threads. At each nodal point arises a simple, thorny, radial spine, which bears at the distal end an elegant verticil of fifteen to twenty flatly expanded, thin, terminal branches.

_Dimensions._--Diameter of the inner shell 0.25 to 0.35, of the outer 2.0 to 2.5.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

Genus 692. _Coelacantha_,[311] R. Hertwig, 1879, Organism. d. Radiol., p. 91.

_Definition._--#Cannosphærida# with a latticed internal shell.

The genus _Coelacantha_ comprises those Cannosphærida in which the inner shell is formed by a fenestrated flint-plate, and exhibits numerous pores between the prominent bases of the radial beams.

1. _Coelacantha anchorata_, R. Hertwig.

_Coelacantha anchorata_, R. Hertwig, 1879, Organism. d. Radiol., p. 92, Taf. ix. fig. 2.

Internal shell slightly mammillate, with thirty to forty radial rods, which are densely studded with verticils of tridentate anchor-threads. External shell with irregular, mostly pentagonal meshes, the bars of which bear the same verticils, each composed of three thin, tridentate anchor-threads. At each nodal point arises a slender radial spine, which bears six verticils, each composed of three to five lateral branches.

_Dimensions._--Diameter of the inner shell 0.5, of the outer 3.0.

_Habitat._--Mediterranean, Messina (R. Hertwig), surface.

2. _Coelacantha mammillata_, n. sp.

Internal shell strongly mammillate, with sixty to eighty radial rods, which are densely studded with cruciate verticils of quadridentate anchor-threads. External shell with irregular, mostly {1642}hexagonal meshes, the bars of which bear the same verticils, each composed of four thin quadridentate anchor-threads. At each nodal point arises a slender, smooth, radial spine, which bears at its distal end a verticil of four large, curved, terminal branches.

_Dimensions._--Diameter of the inner shell 0.4, of the outer 3.2.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

----

Order III. PHÆOGROMIA, Haeckel, 1879.

_Definition._--PHÆODARIA with a simple, not bivalved lattice-shell, which assumes very different forms, but is always provided with a peculiar mouth and peristome on the oral pole of the main axis. Central capsule always excentric, placed in the aboral half of the shell-cavity.

Family LXXVIII. #CHALLENGERIDA#, John Murray (Pl. 99).

_Challengerida_, John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv. p. 471, pl. xxiv. figs. 1, 2.

_Definition._--PHÆODARIA with a monaxonial, usually ovate or lenticular shell, which exhibits a peculiar, fine, regularly hexagonal, diatomaceous structure, and is usually provided with teeth on the mouth, but without articulated feet. Central capsule excentric, placed in the aboral half of the shell-cavity.

The family #Challengerida# represent a large, peculiar, and interesting group of PHÆODARIA, which are, for the most part, inhabitants of great depths, and were perfectly unknown before the discoveries of the Challenger. The first note on these remarkable Radiolaria was given in 1876 by John Murray, in his Preliminary Reports on Work done on board the Challenger (Proc. Roy. Soc. Lond., vol. xxiv. pp. 471, 536, pl. xxiv. figs. 1, 2). He described the peculiar exceedingly beautiful tracery of their shell, similar to that of the Diatomaceæ, the enclosed central capsule coloured by carmine, and the surrounding mass of black-brown pigment lumps (the phæodium). "At times these Challengerida come up with a good deal of sarcode outside of the shell, and two specimens have been seen to throw out elongated pseudopodia" (_loc. cit._, p. 536). He found also the shells in the Radiolarian ooze of the deep sea. The number of different forms found in the collection of the Challenger is so great, that I can describe in the following pages not less than six genera and fifty-eight species. A part of these have already been figured by Dr. John Murray in the Narrative of the Challenger Expedition, vol. i. p. 226, Pl. A, 1885.

In my first preliminary note on the PHÆODARIA, in 1879, I gave a stricter definition {1643}of the Challengerida (Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, 1879, p. 5). But I united at that time the true Challengerida with the Tuscarorida, which, however, are sharply separated by the entirely different structure of their shell. In Plate A given by Dr. John Murray, and mentioned above, figs. 1-14 represent genuine Challengerida, with diatomaceous shell-structure, whilst figs. 15-20 are Tuscarorida, with porcellanous shell-structure. These latter, therefore, are more closely allied to the Circoporida, whilst the Challengerida exhibit a closer affinity to the Medusettida and Castanellida. But the two latter families never possess that peculiar extremely regular and delicate diatomaceous structure which is exhibited only by the Challengerida.

The general form of the Challengerida is rather simple, usually more or less ovate, sometimes nearly triangular, at other times subspherical. In nearly all species, with a few exceptions, the shell is more or less compressed from the two sides, so that its horizontal transverse section is not circular, but elliptical or lanceolate. In many species the shell is more or less lenticular, with a sharp or sometimes keeled margin. This margin lies in the sagittal plane of the body, whilst the two flat sides are right and left. The main axis is always perpendicular, and its oral or anterior pole is marked by the open mouth of the shell; the latter is in the living organism probably the upper pole, whilst the opposite aboral or posterior pole (often marked by large spines) is the lower pole. The dorsal margin of the mouth is usually different from the ventral, and in the majority of species this difference is so striking, that right and left sides of the body may be recognised immediately, the fundamental form being dipleuric or bilaterally-symmetrical. In a few species, however, and mainly in those simplest forms in which the ovate shell has a circular mouth without teeth, and a circular transverse section, that difference is not recognisable, and the ovate shell is monaxonial, as it is in _Gromia_ and _Lagena_ among the Foraminifera (Pl. 99, figs. 19, 20, 22). The size of the shell is in the majority of species between 0.2 and 0.5 mm.; there are, however, some very small species, in which the diameter of the shell is only 0.05 to 0.08, or even less; and some large species, the diameter of which attains 0.8 to 0.9 mm.

The peculiar structure of the siliceous shell-wall, which we call shortly "diatomaceous," and by which the Challengerida differ from all the other PHÆODARIA, has been already represented very well by Dr. John Murray, in Pl. A. of the Narrative (vol. i. p. 266, figs. 1_c_-1_e_, 2_a_, 4_a_, 7_a_, 7_b_). This elegant diatomaceous structure is extremely similar or nearly identical with that well-known regular structure which we find in the common Diatomaceæ or Bacillariæ. The entire surface of the shell is covered with a very great number of very small pit-like depressions, perfectly regular, circular in form, equal in size, and quincuncial in arrangement. The neighbouring equidistant pits are always surrounded by regular hexagonal frames of equal size, and the prominent fine crests of these frames produce the regular hexagonal tracery, which gives to the shell such a striking similarity to that of the Diatomaceæ. According to {1644}the different positions to which the focus of the microscope is brought, the hexagonal tracery exhibits a different appearance; either a regular network of equal hexagonal frames, or a lattice with equal and equidistant circular openings, or a combination of three crossed and equidistant systems of parallel lines (crossed at angles of 120°). All the well-known and often discussed optical phenomena which are observed in the valves of the Diatomaceæ, reappear also on the shell of the Challengerida.

To recognise the true nature of this diatomaceous structure, sections and slides of the shell are required, and also fragments of broken shells, the broken margins of which are of special value for obtaining further explanation. The figures given by Dr. J. Murray (_loc. cit._, Pl. A) have already demonstrated that the pit-like depressions are regular small cavities in the flinty shell-wall, which possess an inner and an outer opening. These intraparietal cavities are either spherical (fig. 7_b_) or cylindrical (fig. 1_d_, 4_a_) or spindle-shaped, with a constriction (fig. 2_a_). Further accurate examinations probably will show a greater variety in their shape. But each cavity constantly possesses two small openings, one on the outer, and the other on the inner surface of the shell-wall. Closer examination (especially of broken shells and slides) proves the presence of these two openings, which in the smaller species seem to be absent on the first view. I may, therefore, suppose that also in the similar valves of the Diatomaceæ, which exhibit exactly the same structure, an inner and an outer opening are always present in each hexagonal pit, and that the very small size alone prevents them from being recognised. The regular hexagonally-framed cavities in the shell-wall of the Challengerida (probably also of the Diatomaceæ) are therefore genuine pores, differing from the pores of other Radiolaria only in their smaller size and the dilatation of the middle part, which is much wider than the two openings.

The mouth of the shell, its single larger opening, exhibits in the various Challengerida a great variety in form and structure, and offers the best means for separating genera and species. According to its essential shape two different subfamilies and six genera may be distinguished in this family. In the first subfamily, Lithogromida, the mouth is a simple large opening in the wall of the shell on the oral pole of its main axis (Pl. 99, figs. 1-15). In the second subfamily, Pharyngellida, the mouth is prolonged into a cylindrical hollow tube, which is prominent into the shell-cavity, and comparable to the pharynx of the Metazoa in general form and function (Pl. 99, figs. 16-20). In this case we may distinguish an inner and an outer mouth of the tubular pharynx.

In a few forms of both subfamilies the mouth is toothless, smooth, and not armed with prominent external spines or teeth, as in _Lithogromia_, the simplest form of all (Pl. 99, fig. 22) and in _Entocannula_ (figs. 19, 20). In the great majority of Challengerida, however, the outer opening of the mouth is armed with one or more teeth, usually strong prominent spines (figs. 1-18). Usually the base of these teeth is {1645}semitubular or a half cylinder, forming a more or less prominent peristome or a proboscis; and always in this case the open concave side of the canal-shaped groove is directed towards the ventral side of the shell, the closed convex side towards the dorsal side. When several teeth arise from the two lateral free margins of the groove, they are also directed towards the ventral side (figs. 2, 12, 17, &c.). Often a deep ventral incision or a guttural constriction separates the base of the proboscis from the genuine shell. The structure of this proboscis or peristome is usually the same as in the diatomaceous shell-wall; but sometimes its lattice-work assumes a different shape.

The opening of the mouth itself is rarely circular, usually it is elliptical or even lanceolate, often triangular. Sometimes two prominent opposite lips may be distinguished as right and left, when the fissure of the mouth is prolonged in a sagittal or longitudinal direction; as upper and lower, when it is prolonged in a frontal or transverse direction. The upper or dorsal lip is always more developed than the lower or ventral; and the entire semitubular proboscis may be regarded as a production of the upper lip. Sometimes the latter attains an extraordinary size and development, the greatest in _Challengeria murrayi_ (Pl. 99, fig. 1).

The teeth of the mouth, which arise from the upper lip, are usually hollow, at least on the base; a prolongation of the shell-cavity arising into the base of the teeth. Their form is very variable, conical, lanceolate, triangular, sabre-shaped, &c. Usually they are more or less curved, and shorter than the radius of the shell; rarely they are straight, and longer than the radius (Pl. 99, figs. 5, 6). More important is their different number, which we have employed for the distinction of subgenera; future observations may prove that they are different genera. The most important are the following cases:--(A.) a single odd dorsal tooth (figs. 5, 16); (B.) two paired lateral teeth (figs. 4, 6, 17); (C.) three teeth, an odd dorsal and two paired lateral (figs. 7, 9, 10); (D.) four paired teeth, two dorsal and two ventral (figs. 3, 13); (E.) five teeth, an odd dorsal and two pairs of lateral (figs. 2, 12); (F.) six teeth in three lateral pairs (fig. 1).

The teeth of the peristome are not the only apophyses which arise from the shell of the Challengerida. In the majority other spines appear on the sagittal margin, which separates the right and left halves of the shell. These marginal spines are characteristic of the genera _Challengeron_ and _Porcupinia_; they are usually radially directed, straight, conical, sometimes solid, at other times hollow. Their number and arrangement is very variable and serves for the distinction of species; the following differences are the most important:--(A.) a single odd spine on the apical pole of the shell, in the principal axis, opposite to the centre of the mouth (Pl. 99, figs. 6, 7); (B.) two aboral spines, a dorsal and a ventral (figs. 8-10); (C.) a bunch or a crowded group of radial spines on the aboral margin of the shell, usually one larger apical spine surrounded by several smaller dorsal and ventral (figs. 11, 12, 16); (D.) numerous radial spines along the whole sagittal margin of the shell (figs. 13-15).

{1646}The _central capsule_ of the Challengerida is constantly placed in the aboral half of the shell-cavity, whilst its oral half is occupied by the phæodium; the intervals between them and the inner surface of the shell are filled up by the calymma. Frequently from the outer surface of the capsule arise numerous branched streams of sarcode, which pierce the calymma and are directed towards the inside of the shell-wall, where they are united by a thin continuous layer of protoplasm (Pl. 99, fig. 1). The phæodium is usually more voluminous than the capsule and envelops the latter on its anterior or oral face; more rarely the entire capsule is hidden in the phæodium. The phæodella, constituting the latter, are of very different sizes, of variable colour, olive and greenish-brown, red-brown, black-brown or nearly black. In some preparations, stained with carmine, numerous red coloured granula, similar to nuclei, were scattered in the phæodium (compare Murray, _loc. cit._, Pl. A, figs. 1-14).

The diameter of the central capsule is usually about one-half or one-third as great as that of the enclosing shell (Pl. 99, figs. 1-20). Its form is either spherical or slightly compressed, spheroidal, or sometimes lenticular. The large nucleus has the same form, is about half as broad as the capsule and contains numerous nucleoli. Sometimes the capsule contained two nuclei of equal size, and in a few specimens the shell contained two central capsules, each with a nucleus, so that the Challengerida seem to propagate also by self-division (Pl. 99, fig. 6).

The astropyle, or the large opening of the central capsule, exhibits the usual radiate operculum of the PHÆODARIA, and the tubular proboscis arising from it. This is constantly placed on the oral or anterior pole of the capsule and directed towards the mouth of the shell. I was never able to discover any parapyle or secondary opening in the central capsule, though numerous and well-preserved specimens of the Challenger collection were accurately examined. It seems therefore that the Challengerida are not TRIPYLEA (as the majority of PHÆODARIA), but MONOPYLEA with a single opening (like the closely allied Medusettida and Castanellida).

_Synopsis of the Genera of Challengerida._

{ Shell smooth, without { adoral teeth and { marginal spines, 693. _Lithogromia_. I. Subfamily Lithogromida. { Shell without pharynx { Shell with adoral or inner prominent tube { teeth, but without of the mouth. { marginal spines, 694. _Challengeria_. { { Shell with adoral { teeth and with { marginal spines, 695. _Challengeron_.

{ Shell smooth, without { adoral teeth and II. Subfamily Pharyngellida.{ marginal spines, 696. _Entocannula_. Shell with a pharynx, { or an inner cylindrical { Shell with adoral tube, arising from the { teeth, but without mouth and prominent { marginal spines, 697. _Pharyngella_. inside. { { Shell with adoral { teeth and with { marginal spines, 698. _Porcupinia_.

{1647}Subfamily 1. LITHOGROMIDA, Haeckel.

_Definition._--#Challengerida# without pharynx, with a simple mouth, not prolonged into an inner prominent tube.

Genus 693. _Lithogromia_,[312] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Challengerida# without pharynx, without adoral teeth and marginal spines.

The genus _Lithogromia_ and the two following genera represent together the subfamily Lithogromida, comprising those Challengerida in which the mouth of the shell is a simple opening, and not prolonged into a pharynx or an internal prominent tube. _Lithogromia_ may be regarded as the common ancestral form of this family, since it is the simplest of all, and possesses no external apophyses, neither teeth on the mouth, nor spines on the margin of the smooth shell.

1. _Lithogromia silicea_, n. sp. (Pl. 99, fig. 22).

Shell ovate, one and a half times as long as broad, not compressed. Transverse section circular. Mouth a simple circular opening with smooth edges about one-third as broad as the shell.

_Dimensions._--Length of the shell 0.2, breadth 0.15; mouth 0.05.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth 600 fathoms.

2. _Lithogromia diatomacea_, n. sp. (Pl. 99, fig. 21).

Shell ovate, lenticular, one and one-third times as long as broad, strongly compressed. Transverse section elliptical. Mouth a broad fissure, half as broad as the shell.

_Dimensions._--Length of the shell 0.27, breadth 0.2; mouth 0.1.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

3. _Lithogromia lenticula_, n. sp.

Shell subcircular, lenticular, about as long as broad, strongly compressed. Transverse section lanceolate. Mouth a narrow fissure, one-third as broad as the shell.

_Dimensions._--Diameter of the shell 0.15, mouth 0.05.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

{1648}Genus 694. _Challengeria_, John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv. p. 536.

_Definition._--#Challengerida# without pharynx, with one or more adoral teeth, but without spines on the sagittal margin.

The genus _Challengeria_, and the following closely allied _Challengeron_, differ from the preceding _Lithogromia_, their ancestral form, in the development of teeth on the mouth of the shell. _Challengeron_ has also radial spines on the sagittal margin, while these are wanting in _Challengeria_. The latter genus exhibits not less than twenty-one, the former twenty-five species, so that both together make by far the greatest part of the family (containing fifty-eight species). They are also more common and more widely distributed than the four other genera of Challengerida, and many species appear in great numbers in certain localities. With a few exceptions living on the surface, they are all inhabitants of great depths.

Subgenus 1. _Challengerantha_, Haeckel.

_Definition._--Peristome with a single simple tooth, which is neither forked nor branched (_Challengeriæ monodontes_).

1. _Challengeria naresii_, John Murray.

_Challengeria naresii_, John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv. pl. xxiv. fig. 1.

_Challengeria naresii_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 236, pl. A, figs. 1, 1_a_-1_e_.

Shell circular or nearly circular, strongly compressed, lenticular. Peristome on the dorsal corner with a single simple vertical tooth, which is nearly straight, conical, with two sharp lateral edges on the base, about half as long as the shell.

_Dimensions._--Diameter of the shell 0.5 to 0.6, length of the tooth 0.2 to 0.3.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, at depths between 1000 and 3000 fathoms.

2. _Challengeria xiphodon_, n. sp.

Shell circular, nearly spherical, slightly compressed. Peristome on the dorsal corner with a single simple vertical tooth, which is straight, three-sided prismatic, and as long as the shell.

_Dimensions._--Diameter of the shell 0.1 to 0.13, length of the tooth 0.1 to 0.12.

_Habitat._--Tropical Atlantic, Stations 349 to 352, surface.

{1649}3. _Challengeria sigmodon_, n. sp.

Shell circular, nearly spherical, slightly compressed. Peristome with a single simple tooth, which is S-shaped, more or less curved, and about one-third as long as the shell.

_Dimensions._--Diameter of the shell 0.3 to 0.4, length of the tooth 0.1 to 0.14.

_Habitat._--North Pacific, Station 231, depth 2250 fathoms.

4. _Challengeria tritonis_, n. sp. (Pl. 99, fig. 5).

Shell ovate, slightly compressed. Peristome with a single simple tooth, which is vertical, straight, slenderly conical, and about half as long as the shell.

_Dimensions._--Diameter of the shell 0.15 to 0.2, length of the tooth 0.1 to 0.12.

_Habitat._--North Atlantic, Færöe Channel, Gulf Stream, in great numbers, in depths from 100 to 600 fathoms. (Expedition of H.M.S. "Triton," 1882), John Murray.

5. _Challengeria pyramidalis_, n. sp.

Shell slenderly ovate, one and a half times as long as broad, slightly compressed. Peristome with a single, simple, large tooth, which is three-sided pyramidal, vertical, straight, and longer than half the shell.

_Dimensions._--Length of the shell 0.6 to 0.8, breadth 0.4 to 0.5; length of the tooth 0.4 to 0.5.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

6. _Challengeria cyrtodon_, n. sp.

Shell ovate, lenticular, strongly compressed. Peristome with a single simple tooth, which is crescent-shaped, curved over the mouth, and about half as long as the shell.

_Dimensions._--Length of the shell 0.4 to 0.5, breadth 0.3 to 0.4; length of the tooth 0.2 to 0.25.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

Subgenus 2. _Challengeretta_, Haeckel.

_Definition._--Peristome with a forked or bifid tooth, or with two parallel lateral teeth (_Challengeria diodontes_).

7. _Challengeria sloggettii_, John Murray (Pl. 99, fig. 4).

_Challengeria harstoni_, John Murray, 1879 (_partim_), _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 14.

Shell triangular, strongly compressed, with three rounded corners, or nearly semicircular; its aboral margin straight, horizontal, longer than the convex, dorsal, and ventral margins. Peristome {1650}with two parallel, triangular pointed teeth, which are obliquely ascending, lamellar, with inflated ovate base, and about as long as the shell-radius.

_Dimensions._--Diameter of the shell 0.2 to 0.3, length of the teeth 0.1 to 0.15.

_Habitat._--Tropical Atlantic, Stations 347, 348, depth 2250 to 2450 fathoms.

8. _Challengeria harstoni_, John Murray.

_Challengeria harstoni_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 14_a_.

Shell subcircular or somewhat triangular, with convex margins. Peristome with two parallel, slender, lanceolate teeth, which are obliquely ascending, and about half as long as the shell-radius.

_Dimensions._--Diameter of the shell 0.15 to 0.18, length of the teeth 0.04 to 0.05.

_Habitat._--North Pacific, Station 231, depth 2250 fathoms.

9. _Challengeria campbelli_, John Murray.

_Challengeria campbelli_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 9.

Shell cordate, nearly triangular, compressed, with blunt apex. Peristome in the excavated middle of the broad base, with two short, parallel, triangular teeth. This species is very similar to _Porcupinia cordiformis_ (Pl. 99, fig. 16), but differs from it in the absence of an internal pharynx and of external apical spines.

_Dimensions._--Diameter of the shell 0.2 to 0.24; length of the teeth 0.03 to 0.05.

_Habitat._--South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms.

10. _Challengeria thomsoni_, John Murray.

_Challengeria thomsoni_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 2.

Shell ovate, slightly compressed, with rounded apical pole. Peristome semitubular, obliquely ascending, nearly straight, in the lower half an open half-cylinder, in the upper half forked, with two parallel, thin, oblique teeth. Sometimes a third small (dorsal) tooth is developed.

_Dimensions._--Length of the shell 0.3 to 0.35, breadth 0.2 to 0.25; length of the peristome 0.08 to 0.12.

_Habitat._--South Atlantic, Stations 318 to 330, surface, and in depths from 1900 to 2900 fathoms.

11. _Challengeria bidens_, n. sp.

Shell ovate, strongly compressed, lenticular. Peristome with two curved, long and thin bristle-shaped teeth, which are obliquely inclined over the mouth, and longer than the radius of the shell.

_Dimensions._--Length of the shell 0.12 to 0.18, breadth 0.1 to 0.14; length of the teeth 0.08 to 0.1.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

{1651}12. _Challengeria havergalli_, John Murray.

_Challengeria havergalli_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, figs. 13, 13_a_.

Shell subspherical, slightly compressed. Peristome semitubular, slender, somewhat curved, in the lower half a simple half-cylinder, in the upper half forked, with two divergent teeth, nearly as long as the shell.

_Dimensions._--Diameter of the shell 0.1 to 0.15, length of the peristome 0.08 to 0.12.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.

13. _Challengeria elephas_, n. sp.

Shell ellipsoidal, not compressed. Peristome very similar to that of _Challengeron diodon_ (Pl. 99, fig. 6), from which this species differs mainly in the absence of an apical spine, and in a more constricted mouth. The two conical teeth of the mouth are very large, nearly as long as the shell, straight, and almost parallel, each tooth has a large hole on the thickened base.

_Dimensions._--Diameter of the shell 0.22, length of the teeth 0.2.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.

Subgenus 3. _Challengerilla_, Haeckel.

_Definition._--Peristome with three teeth or trifid, with an odd dorsal and two paired lateral teeth (_Challengeriæ triodontes_).

14. _Challengeria macleari_, John Murray.

_Challengeria macleari_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 3.

Shell subcircular, lenticular, with a sharp marginal edge. Peristome semitubular, an oblique half-cylinder, with three divergent, short, triangular teeth; the dorsal odd tooth nearly vertical, the paired lateral teeth subhorizontal. Length of the peristome about one-third or one-fourth of the diameter of the shell.

_Dimensions._--Diameter of the shell 0.25 to 0.35, length of the peristome 0.1 to 0.12.

_Habitat._--South Atlantic, Stations 325 to 332, depth 1715 to 2900 fathoms.

15. _Challengeria tridens_, n. sp.

Shell subspherical, slightly compressed. Peristome about as long as the radius of the shell, with three diverging and obliquely descending teeth; the dorsal odd tooth twice as long as the paired lateral teeth.

_Dimensions._--Diameter of the shell 0.08 to 0.12, length of the peristome 0.05 to 0.07.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray.

{1652}16. _Challengeria trigona_, Haeckel.

_Challengeria macleari_, var., John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 3_b_.

Shell triangular, with three rounded corners; the two lateral sides nearly straight, equal, the aboral side more or less convex and somewhat shorter. Peristome a curved half-tube (often longer than in Murray's figure), one-third to one-half as long as the shell, with three short triangular diverging and ascending teeth of equal length.

_Dimensions._--Length of the shell 0.25 to 0.3, breadth 0.2 to 0.25; length of the peristome 0.08 to 0.12.

_Habitat._--South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms.

17. _Challengeria trifida_, n. sp.

Shell ovate, more or less compressed, about two-thirds as long as broad. Peristome semitubular, obliquely ascending, about one-third as long as the shell, in the lower half simple, in the upper trifid, with three curved divergent teeth; the dorsal odd tooth shorter than the paired lateral teeth.

_Dimensions._--Length of the shell 0.3 to 0.36, breadth 0.24 to 0.28.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

Subgenus 4. _Challengeromma_, Haeckel.

_Definition._--Peristome with four to six or more teeth.

18. _Challengeria quadridens_, n. sp.

Shell subglobose, with nearly circular perimeter. Peristome an oblique short and broad tube, the breadth of which is twice as great as its length and equal to the radius of the shell. Margin of the peristome with four divergent, short, triangular teeth, the two dorsal teeth half as long as the two ventral.

_Dimensions._--Diameter of the shell 0.22 to 0.24, breadth of the peristome 0.1.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

19. _Challengeria bromleyi_, n. sp. (Pl. 99, fig. 3).

Shell ovate, lenticular, strongly compressed. Peristome a broad, trapezoidal, horizontal lamella, the breadth of which is twice as great as its length and nearly equal to the diameter of the shell; its margin with four divergent triangular lamellar teeth, the two dorsal teeth three times as long as the two ventral.

_Dimensions._--Length of the shell 0.08 to 0.1, breadth 0.05 to 0.07; breadth of the peristome 0.08.

_Habitat._--North Pacific, Stations 244 to 253, surface, and in various depths.

{1653}20. _Challengeria wildi_, n. sp. (Pl. 99, fig. 2).

Shell subspherical, slightly compressed. Peristome semitubular, curved, as long as the shell-radius; with five curved lamellar teeth, an odd longer dorsal tooth and two pairs of lateral teeth.

_Dimensions._--Diameter of the shell 0.12 to 0.18, length of the peristome 0.08 to 0.12.

_Habitat._--Tropical Atlantic, Stations 347 to 348, depth 2250 to 2450 fathoms.

21. _Challengeria aldrichi_, John Murray, _Challengeria aldrichi_1876, L. N. 27, pl. 24, fig. 2.

_Challengeria aldrichi_, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 4.

Shell subspherical, slightly compressed. Peristome a collar-like curved lamella, the breadth of which is twice as great as its length, and equals the radius of the shell; its margin with six short triangular teeth, two convergent ventral, two external horizontal lateral, and two ascending dorsal.

_Dimensions._--Diameter of the shell 0.2, breadth of the peristome 0.1.

_Habitat._--North Pacific, Station 244 to 248, depth 2050 to 2900 fathoms.

22. _Challengeria murrayi_, n. sp. (Pl. 99, fig. 1).

Shell subcircular, lenticular, strongly compressed. Peristome a trapezoidal, curved, collar-like lamella, the breadth of which is three times as great as its length and equal to the diameter of the shell; its margin with six triangular teeth, disposed like the preceding species, but larger.

_Dimensions._--Diameter of the shell 0.15, breadth of the peristome 0.15.

_Habitat._--North-Western Pacific (south of Japan), Station 231, depth 2250 fathoms.

Genus 695. _Challengeron_, John Murray, 1879, _in litteris et schedulis_.

_Definition._--#Challengerida# without pharynx, with one or more teeth on the mouth, and with marginal spines.

The genus _Challengeron_ has in general the same shape as the preceding closely allied _Challengeria_, but differs from it in the development of radial spines on the sagittal margin of the shell, which in the latter genus is smooth. According to the different number and arrangement of these marginal spines, which give a very singular appearance to them, we divide the twenty-five species of this cosmopolitan genus into four subgenera:--(1) with a single, odd apical spine; (2) with two opposed aboral spines (a dorsal and a ventral); (3) with a bunch of aboral spines; (4) with numerous radial spines along the whole sagittal margin of the shell.

Subgenus 1. _Challengeranium_, Haeckel.

_Definition._--Margin of the shell with a single spine on the apical pole, opposite to the peristome (_Challengeriæ caudatæ_).

{1654}1. _Challengeron monodon_, n. sp.

Shell subspherical, slightly compressed, with a single straight conical spine on the apical pole, about as long as the radius. Peristome with a single vertical, straight, conical tooth, diametrically opposite to the apical spine and of the same length. (Similar to _Challengeria naresii_.)

_Dimensions._--Diameter of the shell 0.2 to 0.3, length of the two opposite spines 0.1 to 0.15.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

2. _Challengeron cochlear_, n. sp.

Shell nearly circular, lenticular, strongly compressed, with a single straight conical spine on the apical pole, about half as long as the radius. Peristome spoon-shaped, obliquely curved and inclined over the mouth, with a single terminal tooth, somewhat longer than the radius.

_Dimensions._--Diameter of the shell 0.1, length of the peristome 0.06.

_Habitat._--Indian Ocean, Cocos Islands, Rabbe, surface.

3. _Challengeron diodon_, n. sp. (Pl. 99, fig. 6).

Shell ovate, slightly compressed, with a single straight conical spine on the aboral pole, half as long as the radius. Peristome short and broad, collar-shaped, about twice as broad as long, and half as long as the radius, obliquely inclined over the mouth, with two divergent straight teeth, which are conical and longer than the shell-radius; beyond each tooth a large ovate hole in the wall of the peristome.

_Dimensions._--Diameter of the shell 0.08 to 0.1, length of the teeth 0.06 to 0.08.

_Habitat._--South-Eastern Pacific, Station 298, depth 2225 fathoms.

4. _Challengeron pearceyi_, n. sp. (Pl. 99, fig. 7).

Shell ellipsoidal or subspherical, scarcely compressed, with a single straight conical spine on the apical pole, about as long as the diameter. Peristome slender, semitubular, nearly as long as the diameter, somewhat obliquely inclined over the mouth, with three divergent triangular or lanceolate teeth; the dorsal odd tooth about twice as large as the paired lateral teeth.

_Dimensions._--Diameter of the shell 0.08 to 0.12, length of the peristome 0.08 to 0.1.

_Habitat._--Antarctic Ocean, between Kerguelen and Heard Island, Station 157.

5. _Challengeron swirei_, John Murray.

_Challengeria swirei_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 11.

Shell subspherical or somewhat ovate, with a single straight conical spine on the apical pole, about as long as the radius. Peristome slender, semitubular, straight and vertical, nearly as long as the shell, with three pointed teeth, an odd longer terminal and two paired shorter lateral.

_Dimensions._--Diameter of the shell 0.06 to 0.08, length of the peristome 0.05 to 0.06.

_Habitat._--Antarctic Ocean, Station 157, surface, common.

{1655}6. _Challengeron triodon_, n. sp.

Shell ovate, one and a half times as long as broad, not compressed, with a single short and stout conical spine on the apical pole, shorter than half the radius. Peristome short and broad, collar-shaped, nearly half as broad and one-third as long as the shell, with three divergent terminal teeth, an odd dorsal and two paired lateral.

_Dimensions._--Length of the shell 0.25 to 0.3, breadth 0.15 to 0.2; length and breadth of the peristome 0.1.

_Habitat._--North Pacific, Station 245, surface.

Subgenus 2. _Challengerebium_, Haeckel.

_Definition._--Margin of the shell with two widely distant aboral spines, opposite in the sagittal plane, a dorsal and a ventral.

7. _Challengeron balfouri_, John Murray.

_Challengeria balfouri_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 10.

Shell subcircular, lenticular, strongly compressed, with two short divergent spines on the apical margin (a dorsal and a ventral). Peristome slender, semitubular, as long as the radius, vertical, in the distal half forked, with two parallel teeth.

_Dimensions._--Diameter of the shell 0.08 to 0.16, length of the peristome 0.04 to 0.08.

_Habitat._--North Atlantic, Stations 353 to 354, Hebrides, surface.

8. _Challengeron golfense_, n. sp.

Shell ovate, lenticular, compressed, with two short divergent spines on the apical margin (a dorsal and a ventral). Peristome slender, semitubular, half as long as the radius, with three terminal teeth, two short, vertically ascending, paired teeth and a larger odd tooth, which is inclined obliquely over the mouth.

_Dimensions._--Diameter of the shell 0.15 to 0.2, peristome 0.05 to 0.07.

_Habitat._--North Atlantic, Færöe Channel, Gulf Stream, surface and at various depths, John Murray.

9. _Challengeron richardsii_, n. sp. (Pl. 99, fig. 8).

Shell subcircular, lenticular, strongly compressed, with two stout, divergent, straight spines on the aboral margin (a dorsal and a ventral) which reach the length of the radius. Peristome slender, semitubular, slightly curved, about as long as the radius, with three short, divergent, {1656}terminal teeth. Mouth obliquely truncate. The dorsal odd tooth is nearly vertical, the two lateral paired teeth almost horizontal.

_Dimensions._--Diameter of the shell 0.2 to 0.25, length of the spines and the peristome 0.08 to 0.12.

_Habitat._--Antarctic Ocean, Station 157, surface, common.

10. _Challengeron fergusoni_, n. sp. (Pl. 99, fig. 9).

Shell isosceles triangular, with three slightly convex edges and two short, nearly vertically descending spines on the two corners of the aboral margin. Peristome inversely funnel-shaped, with a deep ventral incision on the base, and three broad, ovate, triangular teeth. The dorsal odd tooth is nearly vertical, whilst the two lateral paired teeth are almost horizontal; therefore the angle between the former and the latter is about a right angle.

_Dimensions._--Diameter of the shell 0.2 to 0.3, length of the peristome 0.1.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.

11. _Challengeron tizardi_, John Murray.

_Challengeria tizardi_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol i. p. 226, pl. A, figs. 7-7_b_.

Shell nearly equilateral triangular, with concave ventral, convex dorsal and aboral edges, on the two corners of the latter two opposite horizontal spines (a dorsal and a ventral). Peristome auriculate and bilobate, with a deep ventral incision on the base, and three pointed triangular teeth, the upper margins of which are nearly horizontal.

_Dimensions._--Diameter of the shell 0.22 to 0.3, length and breadth of the peristome 0.01 to 0.12.

_Habitat._--South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms.

12. _Challengeron triangulum_, n. sp. (Pl. 99, fig. 10).

Shell nearly equilateral triangular, with three slightly convex or nearly straight sides, and two opposite obliquely descending and diverging spines on the two corners of the aboral margin. Peristome auriculate and bilobate, with a very thin basal neck and a deep incision on its ventral side; its distal margin is obliquely truncate, and exhibits an odd ascending dorsal tooth and two parallel, paired, descending, lateral teeth.

_Dimensions._--Diameter of the shell 0.2 to 0.3; length and breadth of the peristome 0.1 to 0.12.

_Habitat._--North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.

Subgenus 3. _Challengeridium_, Haeckel.

_Definition._--Margin of the shell smooth on the dorsal and the ventral side, but with three to five or more large spines (or a bunch of spines) on the aboral side; the middle spine is placed in the main axis, and larger than the others.

{1657}13. _Challengeron bisternum_, n. sp.

Shell subcircular, lenticular, strongly compressed, with three stout conical spines on the aboral pole; the middle spine is placed in the main axis, as long as the radius and three times as long as the two others. Peristome semitubular, straight, vertical, about as long as the radius, with three divergent teeth, the middle of which is odd and twice as large as the two paired lateral teeth.

_Dimensions._--Diameter of the shell 0.22; length of the peristome 0.1.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

14. _Challengeron heptacanthum_, n. sp.

Shell ovate, slightly compressed, with a series of five stout, conical, radial spines on the aboral margin; the middle spine is placed in the main axis and longer than the radius, twice as long as the two next, and three times as long as the more distant spines. Peristome short and broad, collar-shaped, with two large, divergent, straight teeth, each of which is longer than the shell-radius and bears at its base a large hole.

_Dimensions._--Length of the shell 0.09 to 0.11, breadth 0.07 to 0.08; length of the teeth 0.07.

_Habitat._--Tropical Atlantic, Stations 347, 348, depth 2250 and 2450 fathoms.

15. _Challengeron crosbiei_, n. sp. (Pl. 99, fig. 11).

Shell ovate, strongly compressed, with a series of seven to nine conical spines on the aboral margin; the middle spine is placed in the main axis, as long as the radius, and much larger than the six or eight other spines. Peristome short and broad, collar-like, with several small spines and two slender, widely distant, conical teeth, which are half as long as the shell, and curved towards one another like a pincer, each with a large hole at its base.

_Dimensions._--Length of the shell 0.08 to 0.09, breadth 0.06 to 0.07; length of the two larger teeth 0.04 to 0.05.

_Habitat._--Central Pacific, Station 270 to 274, depth 2350 to 2925 fathoms.

16. _Challengeron buchanani_, n. sp. (Pl. 99, fig. 12).

Shell ovate, slightly compressed, with a terminal comb of nine to twelve conical radial spines, densely crowded on the aboral pole; the middle spine is placed in the main axis, about half as long as the shell and much larger than the others. Peristome subconical, semitubular, recurved, half as long as the shell, with five triangular teeth; the dorsal odd tooth is inclined backwards, the two parallel pairs of lateral teeth directed ventrally.

_Dimensions._--Length of the shell 0.15 to 0.18, breadth 0.1 to 0.12; length of the peristome 0.06 to 0.08.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

{1658}Subgenus 4. _Challengerosium_, Haeckel.

_Definition._--Margin of the shell dentated or serrated, with a continuous series of numerous short radial spines.

17. _Challengeron channeri_, John Murray.

_Challengeron channeri_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 12.

Shell subcircular, lenticular, strongly compressed, with fourteen to eighteen slender, straight, radial spines on the margin; the spines are straight, equidistant, cylindrical, and about as long as the radius of the shell. Peristome short, with two parallel, vertical, lateral, straight teeth, which are less than half the length of a spine.

_Dimensions._--Diameter of the shell 0.14 to 0.17; length of the spines 0.06 to 0.08.

_Habitat._--North Pacific, Station 231, depth 2250 fathoms.

18. _Challengeron moseleyi_, n. sp. (Pl. 99, fig. 14).

Shell circular, lenticular, strongly compressed, with thirty to forty slender, straight, equidistant, radial spines on the margin, larger and smaller spines alternating; the larger spines are about as long as the radius, the smaller only half as long. Peristome short, tubular, with two divergent ovate or nearly triangular teeth, a dorsal and a ventral, about as long as the shorter marginal spines.

_Dimensions._--Diameter of the shell 0.13 to 0.15; length of the larger spines 0.06 to 0.07, of the smaller 0.03 to 0.04.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

19. _Challengeron bethelli_, John Murray.

_Challengeron bethelli_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 6.

Shell subcircular, lenticular, strongly compressed, with numerous (twenty to thirty) short conical spines on the margin (often wanting in the upper part of the dorsal margin). Peristome with a deep labial incision and two parallel triangular lateral teeth, the upper margin of which is horizontal.

_Dimensions._--Diameter of the shell 0.2 to 0.25; length of the spines 0.02 to 0.03.

_Habitat._--North Pacific, Stations 238, 241 (off Japan), depth between 2300 and 3950 fathoms.

20. _Challengeron bathybium_, n. sp.

Shell subcircular, lenticular, slightly compressed, with a corona of numerous (thirty to forty or more) short, conical, radial spines on the margin. Peristome helmet-shaped, nearly as long as the {1659}radius, with two widely divergent, conical, curved teeth, a vertical dorsal and a nearly horizontal ventral tooth.

_Dimensions._--Diameter of the shell 0.22; length of the peristome 0.1.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

21. _Challengeron johannis_, n. sp.

Shell ovate, slightly compressed, with a corona of numerous (forty to sixty or more) short radial spines on the margin, ten to fifteen of them (in the aboral half) are pyramidal, and much larger than the others. Peristome helmet-shaped, about one-third as long as the shell, with a deep bosom and two widely divergent teeth on the concave upper margin, a forked dorsal and a conical ventral.

_Dimensions._--Length of the shell 0.13, breadth 0.1; length of the peristome 0.04.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray.

22. _Challengeron carpenterii_, John Murray.

_Challengeron carpenterii_, John Murray, 1877, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 8.

Shell ovate, with a series of twelve to fifteen short, conical, radial spines on the aboral half of the margin. Peristome slender, semitubular, nearly as long as the shell, in the upper half forked, with two short parallel teeth.

_Dimensions._--Length of the shell 0.13 to 0.18, breadth 0.1 to 0.14; length of the peristome 0.1 to 0.12.

_Habitat._--Tropical Atlantic, Stations 347 to 348, depth 2250 to 2450 fathoms.

23. _Challengeron ciliatum_, n. sp.

Shell ovate, slightly compressed, with numerous (forty to fifty or more) short and thin, bristle-shaped, radial spines on the margin. Peristome obliquely truncate, with three curved spines; the dorsal odd spine subvertical, nearly as long as the radius, and much stronger than the two parallel, nearly horizontal, lateral spines.

_Dimensions._--Length of the shell 0.15, breadth 0.11; length of the peristome 0.1.

_Habitat._--North Pacific, Station 231, depth 2250 fathoms.

24. _Challengeron willemoesii_, n. sp. (Pl. 99, fig. 13).

Shell broadly-ovate or nearly circular, lenticular, with numerous (fifty to sixty) short and stout, conical, radial spines on the margin, increasing in size towards the aboral pole; the spines are alternately larger and smaller, the largest about half as long as the radius. Peristome helmet-shaped or half conical, longer than the radius of the shell, with two pairs of conical, curved, {1660}divergent teeth; the terminal teeth are the halves of a forked dorsal tooth and diverge laterally; the lower teeth are nearly horizontal and directed ventrally.

_Dimensions._--Diameter of the shell 0.13 to 0.15; length of the peristome 0.07 to 0.1.

_Habitat._--Tropical Pacific, Stations 274 to 276, depth 2350 to 2750 fathoms.

25. _Challengeron wyvillei_, n. sp. (Pl. 99, fig. 15).

Shell ovate, lenticular, strongly compressed, with numerous (forty to fifty) short, conical, radial spines on the margin; the spines are larger on the aboral side and spinulate. Peristome narrow, with two parallel, lateral, lamellar, forked teeth, about as long as the radius; the upper branch of the forks is sabre-shaped, obliquely truncate, subvertical, ciliate, and much broader than the lower nearly horizontal branch, which is directed towards the ventral side and curved upwards.

_Dimensions._--Length of the shell 0.12 to 0.16, breadth 0.1 to 0.14; length of the peristome 0.08 to 0.11.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

Subfamily 2. PHARYNGELLIDA, Haeckel.

_Definition._--#Challengerida# with a pharynx, or an internal prominent mouth tube.

Genus 696. _Entocannula_,[313] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Challengerida# with a pharynx, without teeth on the mouth, and without marginal spines.

The genus _Entocannula_ and the two following genera represent together the subfamily Pharyngellida, differing from the preceding Lithogromida in the development of a peculiar pharynx, an internal, cylindrical, or funnel-shaped tube, which is conspicuous, leads from the mouth into the shell-cavity, and is provided with an inner and an outer opening. The Pharyngellida are much rarer than the Lithogromida; only ten species have been observed of the former, fifty of the latter. _Entocannula_ is the simplest form of the Pharyngellida, having a smooth shell, without aboral teeth and marginal spines; it differs from _Lithogromia_ only in the possession of the pharynx. One remarkable species is covered entirely with extremely thin, flinty hairs, and may represent therefore a peculiar genus, _Trichogromia_.

{1661}1. _Entocannula circularis_, n. sp.

Shell circular or nearly circular, lenticular, strongly compressed. Pharynx cylindrical, one-third or one-fourth as broad as the shell, twice as broad as long, its outer and inner apertures of equal breadth. Surface smooth.

_Dimensions._--Diameter of the shell 0.20 to 0.32, of the pharynx 0.07 to 0.09.

_Habitat._--North Pacific, Station 250, depth 3050 fathoms.

2. _Entocannula subglobosa_, n. sp.

_Challengeria bromleyi_, (_partim_), John Murray, 1879, _in schedulis_ Chall. Coll.

Shell circular, nearly spherical, slightly compressed. Pharynx funnel-shaped, truncate, conical, its outer opening twice as broad as the inner. Surface smooth.

_Dimensions._--Diameter of the shell 0.25 to 0.28, of the inner mouth 0.05.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

3. _Entocannula infundibulum_, n. sp. (Pl. 99, fig. 19).

_Challengeria bromleyi_ (_partim_), John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 5.

Shell ovate, truncate at the mouth, slightly compressed. Pharynx funnel-shaped, its outer aperture two to three times as broad as the inner. Surface smooth.

_Dimensions._--Length of the shell 0.22 to 0.28, breadth 0.2 to 0.25; inner mouth 0.04 to 0.08.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

4. _Entocannula hirsuta_, n. sp. (Pl. 99, fig. 20).

_Trichogromia hirsuta_, Haeckel, 1881, Manuscript.

Shell ovate. Pharynx cylindrical, one-fourth as broad as the shell, its inner and outer apertures of equal breadth. The whole surface of the shell, and mainly the outer mouth, is densely covered with thin, curved, siliceous bristles.

_Dimensions._--Length of the shell 0.27 to 0.36, breadth 0.2 to 0.3; mouth 0.05 to 0.08.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth 600 fathoms.

Genus 697. _Pharyngella_,[314] n. gen.

_Definition._--#Challengerida# with a pharynx, and with one or more teeth on the mouth, but without marginal spines.

The genus _Pharyngella_ differs from the preceding _Entocannula_, its ancestral form, in the development of one or more teeth on the peristome, and exhibits therefore the same relation to it that _Challengeria_ bears to _Lithogromia_. Only a few species of this genus have been observed, all in the Atlantic.

{1662}1. _Pharyngella monoceros_, n. sp.

Shell ovate, slightly compressed, with a single large tooth on the dorsal corner of the peristome. The tooth is cylindro-conical, half as long as the shell, straight or slightly curved, and lies in the main axis of the shell. Pharynx cylindrical, straight, half as long as the shell-radius. This species is very similar to _Challengeria tritonis_ (Pl. 99, fig. 5), and to the common cosmopolitan _Challengeria naresii_, but differs generically from them in the possession of the pharynx.

_Dimensions._--Diameter of the shell 0.25 to 0.28; length of the tooth 0.14.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

2. _Pharyngella gastrula_, n. sp. (Pl. 99, fig. 18).

Shell ovate. Peristome with two parallel, vertical, straight, pointed teeth, which are half as long as the shell-radius. Pharynx of the same length, cylindrical or funnel-shaped, its outer aperture scarcely broader than the inner.

_Dimensions._--Length of the shell 0.3 to 36, breadth 0.24 to 0.3; teeth and pharynx 0.07 to 0.09.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth 600 fathoms.

3. _Pharyngella invaginata_, n. sp.

Shell circular, slightly compressed or nearly spherical. Peristome with two parallel, vertical, straight, pointed teeth, which are about as long as the shell-radius. Pharynx of the same length, funnel-shaped; its outer aperture twice as broad as the inner.

_Dimensions._--Diameter of the shell 0.2 to 0.22, teeth and pharynx 0.05.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

4. _Pharyngella gastræa_, n. sp. (Pl. 99, fig. 17).

Shell broad, ovate or nearly circular, lenticular, strongly compressed. Peristome with two parallel, pointed teeth, which are nearly as long as the shell-radius, slightly curved, and obliquely inclined over the mouth. Pharynx half as long, cylindrical, obliquely descending; its outer and inner apertures of equal breadth.

_Dimensions._--Diameter of the shell 0.3 to 0.33, teeth 0.12, pharynx 0.06.

_Habitat._--South Atlantic, Stations 328 to 334, surface.

Genus 698. _Porcupinia_,[315] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Challengerida# with a pharynx, with teeth on the mouth and marginal spines.

The genus _Porcupinia_ differs from the preceding _Pharyngella_ in the development {1663}of marginal spines, and exhibits therefore the same relation to it that _Challengeron_ bears to _Challengeria_. Only two species have been observed; the first of these bears, besides the large marginal spines, numerous flinty bristles on the surface of the shell.

1. _Porcupinia aculeata_, n. sp.

Shell ovate, one and one-third times as long as broad, slightly compressed, covered with short, bristle-shaped spines over the whole surface, similar to _Entocannula hirsuta_ (Pl. 99, fig. 20). The keeled margin is armed with numerous long and stout radial spines, which are alternately larger and smaller, as in _Challengeron moseleyi_ (Pl. 99, fig. 14); the larger about as long as the radius, the smaller half as long. Peristome with two straight, parallel teeth. Pharynx funnel-shaped, half as long as the radius, its outer aperture twice as broad as the inner.

_Dimensions._--Length of the shell 0.24, breadth 0.18; peristome 0.05.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

2. _Porcupinia cordiformis_, n. sp. (Pl. 99, fig. 16).

Shell heart-shaped, nearly triangular, with a deep, concave bosom at the broad oral base, and a bunch of five to nine divergent spines at the blunt aboral apex, the middle spine (in the main axis) larger than the others. Peristome with two parallel, short, triangular teeth, which are obliquely inclined over the mouth (their upper convex edge nearly horizontal). Pharynx cylindrical, short, curved, and obliquely descending.

_Dimensions._--Diameter of the shell 0.2 to 0.25, of the pharynx 0.05 to 0.08.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

Family LXXIX. #MEDUSETTIDA#, n. fam. (Pls. 118-120).

_Definition._--PHÆODARIA with a simple, ovate, hemispherical or cap-shaped lattice-shell of peculiar alveolate structure, and with hollow articulate feet surrounding the widely open mouth. Central capsule excentric, placed in the aboral half of the shell-cavity.

The family #Medusettida# represents a peculiar group of remarkable PHÆODARIA, which are similar to the Challengerida and Tuscarorida in the general form of the monaxonian shell and its apophyses, but differ from both families in the strange alveolate structure of the shell and of the hollow articulate feet surrounding its mouth. All the forms of this family here described are new, and not a single species was known before the discoveries of the Challenger. The majority seem to be inhabitants of the deep-sea, and occur mainly in those places where other families of PHÆODARIA (Aulacanthida, Aulosphærida, Coelodendrida) are also well represented; they are, however, nowhere so common as these latter families. Their long feet and the small delicate {1664}shell are extremely fragile, so that complete and well-preserved specimens are rare. Some species are among the most admirable forms of Radiolaria, and are similar to small elegant Medusæ, _e.g._, _Medusetta_ (Pl. 120, figs. 1-4), _Gazelletta_ (Pl. 118, fig. 1), and _Gorgonetta_ (Pl. 119).

The shell of the Medusettida is usually very small and delicate, in comparison to the long, often exceedingly large, feet, which depend from the margin of its mouth. From the size and the weight of these feet, we must suppose that the shell floats in the water in the same position as in the NASSELLARIA, so that the main axis is vertical, and the open mouth with the feet on its lower pole. The form of the shell exhibits the same varieties as the similar umbrella of the Medusæ. It is usually more or less hemispherical, sometimes flatter, cap-shaped, at other times more highly vaulted, campanulate or ovate. The similarity with the umbrella of a Medusa is so great, that in many species the large lower opening on the mouth of the shell is surrounded by a prominent ring or diaphragm, comparable to the velum of the Craspedotæ or Hydromedusæ (Pl. 120, figs. 3-4).

The structure of the shell, which we term shortly "alveolate," is very remarkable, and seems to be different from that of the other PHÆODARIA. Its reticulate appearance seems to indicate at first sight the usual lattice-shell, pierced by numerous very small pores (Pl. 118, figs. 1-3). But as soon as we make the shell dry, air always enters into its thin walls, and each apparent pore is found to be a small alveole or a separate compartment, which contains a small bubble of air (Pl. 120, figs. 11, 16). The thin wall of the shell is therefore double, composed of two parallel, very thin lamellæ of silica, which are little distant from one another, and are connected by a network of small rods or septa. This network is rarely regular, with square meshes (Pl. 118, fig. 3), or with hexagonal or triangular meshes (Pl. 116, fig. 2); it is usually irregular, with polygonal meshes (Pl. 120, figs. 11-16). The size of the meshes or alveoles is usually smallest on the aboral apex of the shell, and increases gradually towards the mouth. The largest alveoles are around the mouth, on the velum-shaped peristome, and here the marginal alveoles of the shell pass directly over into the separate alveoles or hollow compartments of the articulate feet (Pl. 118, fig. 1). Probably each alveole is a separate compartment, filled up by jelly, and has a small opening or pore on its inside; this pore is very distinct in the marginal alveoles of some larger species (Pl. 116, fig. 1_a_; Pl. 120, fig. 14), but I have not been able to recognise it everywhere. Moreover, it often happens that the alveoles are apparently completely closed. In some smaller species the alveolate structure seems to be present only in the peripheral part of the shell, whilst the central part is solid.

The outer convex surface of the shell is usually smooth, sometimes papillate (Pl. 116, fig. 1), at other times studded with small, conical, radial spines (Pl. 118, fig. 1; Pl. 120, figs. 4-11). Prolonged cylindrical spines or tubes are rarely {1665}scattered over the surface (Pl. 116, figs. 1, 2). In some genera a long vertical or oblique spine is developed from the apex of the shell, and is comparable to the "apical horn" of the NASSELLARIA (Pl. 118, figs. 2, 3; Pl. 120, figs. 1-4).

The mouth of the shell, or the large opening on the lower pole of its vertical main axis, is usually widely open, circular or polygonal, more rarely constricted. In many species the peristome is broadened and its margin developed in the form of a horizontal diaphragm, which constricts the entrance into the shell-cavity, and is comparable to the velum of the Hydromedusæ (Pl. 120, figs. 1-4). Sometimes the margin of the velum is fringed and bears numerous small dependent filaments of silica, comparable to the marginal tentacles of many Medusæ (Pl. 118, figs. 1, 3; Pl. 120, fig. 16). Rarely the mouth is strongly constricted and prolonged into a narrow, long, cylindrical tube, comparable to a proboscis; its opening is usually fringed (Pl. 116, figs. 1, 2).

The hollow articulate feet, or the large radial apophyses of the peristome, are the most remarkable organs of the Medusettida, and occur in the same form in no other family of Radiolaria. Their number is variable from three to twelve or more, and is here employed for the distinction of genera, as it is rather constant; the most frequent number is four (_Medusetta_) or six (_Gazelletta_). The feet are usually cylindrical, much longer than the shell, and more or less curved; more rarely they are straight or slightly compressed. They are always articulate, and divided by numerous transverse parallel septa into hollow compartments or alveoles; the transversely striated appearance of the feet is brought about by these septa. The alveoles have usually the form of short discoidal cylinders, and are broader than long (Pl. 120, figs. 5-13); rarely they are longer than broad (fig. 15). The septa between the alveoles are always perforated by a small opening and usually this opening is prolonged into a shorter or longer tubule, comparable to the siphuncle in the septa of the chambered shells of Cephalopoda; as in these latter, the succeeding siphons are arranged in a continuous series, which lies either in the axis of the foot or parallel to it (Pl. 120, figs. 8, 13, 15). The siphons are directed towards the distal end of the foot, so that, _e.g._, the siphon which arises from the septum between the ninth and tenth alveole, projects into the cavity of the latter. The communicating cavities of all the alveoles are filled up by jelly. In the dry shells, which are cleaned by hot mineral acids or by fire, and in which, therefore, the jelly is destroyed, the cavities become easily filled by air-bubbles (Pl. 120, figs. 8, 11, 15). Whilst the alveoles of each foot always form a long simple series, this series becomes doubled on the base of the larger feet, where they are broadened, and pass over into the compartments of the peristome (Pl. 122, figs. 10, 11, 14). The terminal alveole of each foot is closed.

The feet of the Medusettida are rarely quite simple and smooth (Pl. 120, figs. 1, 5, 7, 10, &c.). Usually they are armed with numerous spines or with elegant pencils of spathillæ. These secondary appendages or branches are also hollow, with a {1666}thin wall of silex; but they seem usually not to communicate with the alveoles of the foot directly; the cavities of the foot and its appendages are separated by a thin, solid septum. In _Medusetta_ the convex outer edge of each curved foot is studded with a series of simple alveolate branches (Pl. 120, figs. 2-4). In _Gazelletta_, the feet are usually armed with verticillate or alternate spines, which are either simple or branched (Pl. 120, figs. 11-15); sometimes each branch is elegantly arborescent (Pl. 118, fig. 1). Sometimes the distal end of each branch is armed with a spathilla or a coronet of recurved teeth. The branches attain their highest development in the admirable _Gorgonetta_ (Pl. 119). The twelve feet of this most interesting genus are differentiated into two different and alternating groups, six descending and six ascending. The six upper or ascending feet are arborescent, and each branch is armed at the distal end with a spathilla (figs. 1, 2). The six lower or descending feet are covered with most elegant arborescent pencils or anchor-bearing trees; each terminal branch of a tree is armed with two spathillæ, a smaller terminal and a larger below it (figs. 3, 4). The distal ends of the feet are rarely simple, usually they are forked or branched, or armed with peculiar spathillæ; and sometimes these terminal branches are very large (Pls. 118, 119).

The _central capsule_ of the Medusettida is usually subspherical or somewhat lenticular, and hidden in the aboral or upper part of the shell-cavity, whilst its oral or lower part is filled up by the phæodium (Pl. 120, figs. 2, 9, 10, 11). Sometimes the phæodium is very large and prominent at the aperture of the mouth (Pl. 118, figs. 2, 3; Pl. 119, fig. 1). The nucleus is usually ellipsoidal, half as large as the central capsule, and includes numerous nucleoli. The membrane of the central capsule seems in all Medusettida to possess only one opening, the astropyle or main-opening with a radiate operculum and proboscis, placed at the lower or oral pole (Pl. 120, fig. 2). I have never been able to observe any secondary opening or parapyle. The free space between the shell wall and the capsule is filled up by the calymma, which also includes the phæodium. The jelly of the calymma is probably in direct continuity with the jelly which fills up the alveoles of the shell-wall and of the articulate feet.

_Synopsis of the Genera of Medusettida._

I. Subfamily Euphysettida. { Three equal feet, 699. _Cortinetta_. Peristome of the shell with { a corona of three or four { Four equal feet, 700. _Medusetta_. feet. Apex of the shell { (usually) with an apical { One large and three horn. { small feet, 701. _Euphysetta_.

{ Six descending feet, 702. _Gazelletta_. { II. Subfamily Gazellettida. { Six descending and six Peristome of the shell with { ascending alternating six to twelve or more feet. { feet, 703. _Gorgonetta_. Apex of the shell (usually) { without apical horn. { Numerous (ten to twenty { or more) descending { feet, 704. _Polypetta_.

{1667}Genus 699. _Cortinetta_,[316] n. gen.

_Definition._--#Medusettida# with three articulate feet on the peristome.

The genus Cortinetta comprises Medusettida which exhibit the minimum number of feet, three, and which therefore may be compared to the tripodal NASSELLARIA (_Cortina_, _Cortiniscus_, _Tripodiscus_, &c.). This similarity is the greater, as in the few observed species an apical horn is developed (as also in the following genus). The three feet are in the two species observed of equal size and similar form, and equidistant, so that they cannot be distinguished as an odd caudal and two paired lateral feet, as in the similar NASSELLARIA.

1. _Cortinetta tripodiscus_, n. sp. (Pl. 117, fig. 7).

Shell campanulate, covered with numerous curved ascending bristles, with a prominent annular velum on the peristome, similar to that of _Medusetta craspedota_. (Pl. 120, fig. 4). Feet equal, widely divergent and equidistant, somewhat longer than the shell, slightly curved, and covered on their convex outer edge with a series of short lateral branches, the three ramules of which bear a spathilla. Apical horn conical, straight, about as long as the shell, also covered with curved bristles.

_Dimensions._--Length of the shell 0.14, breadth 0.11; length of the feet 0.16, of the apical horn 0.11.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

2. _Cortinetta cortiniscus_, n. sp.

Shell campanulate, subspherical, thorny, with a prominent annular velum on the peristome. Feet equal, very large, widely divergent, about three times as long as the shell and studded with arborescent branches, similar to those of _Gazelletta drymonema_ (Pl. 118, fig. 1). Apical horn slender, conical, straight, thorny, twice as long as the shell.

_Dimensions._--Length of the shell 0.18, breadth 0.16; length of the feet 0.5 to 0.6, of the apical horn 0.33.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.

Genus 700. _Medusetta_,[317] n. gen.

_Definition._--#Medusettida# with four equidistant articulate feet of equal size on the peristome.

The genus _Medusetta_ comprises those forms of the family which bear on the peristome four equal radial feet, and therefore exhibit a striking similarity to many {1668}small Medusæ (_e.g._, _Codonium_, _Tiara_, _Sarsia_, &c.). This similarity is the greater, as usually the four feet are elegantly curved and the entrance in the shell-cavity partly closed by a marginal diaphragm, comparable to the velum of the Craspedotæ or Hydromedusæ. In all the species observed the apex of the shell bears a slender vertical or curved spine, comparable to the apical horn of the NASSELLARIA. In most species the feet bear on their convex outside a series of teeth or branches, which are also alveolate.

1. _Medusetta codonium_, n. sp. (Pl. 120, fig. 1).

Shell ovate, smooth, twice as broad as the constricted mouth. Apical horn about as long as the shell, nearly straight, smooth. Feet cylindrical, smooth, irregularly curved, about as long as the shell.

_Dimensions._--Length of the shell 0.08, breadth 0.05.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

2. _Medusetta tiara_, n. sp.

Shell campanulate, smooth, about as long as broad, and three times as broad as the constricted mouth, which is surrounded by a horizontal broad ring, like the velum of a Hydromedusa. Apical horn conical, straight, half as long as the shell. Feet divergent, irregularly curved, twice as long as the shell.

_Dimensions._--Length of the shell 0.07, breadth 0.06.

_Habitat._--North Atlantic (Færöe Channel), John Murray, surface.

3. _Medusetta minima_, n. sp.

Shell slenderly ovate, smooth, about twice as long as broad, twice as broad as the constricted mouth. Apical horn straight, vertical, of the same length. Feet somewhat longer, very thin, slightly curved at the base, in the distal half nearly parallel and descending vertically.

_Dimensions._--Length of the shell 0.06, breadth 0.03.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

4. _Medusetta quadrigata_, n. sp. (Pl. 120, fig. 2).

Shell ovate, campanulate, smooth, little broader than the wide open mouth. Apical horn longer than the shell, more or less curved, smooth. Feet cylindrical, about as long as the shell, strongly curved and somewhat spirally revoluted, with a series of short curved teeth on the abaxial margin.

_Dimensions._--Length of the shell 0.07 to 0.09, breadth 0.04 to 0.06.

_Habitat._--North Pacific (off Japan), Stations 231 to 237, surface.

{1669}5. _Medusetta tetranema_, n. sp. (Pl. 120, fig. 3).

Shell campanulate, conical, smooth, nearly twice as broad as the constricted mouth, without prominent velum. Apical horn somewhat shorter, straight, conical, thorny. Feet strongly curved inwards, convergent, twice as long as the shell, each with four to six strong, ascending, alveolate branches on the abaxial margin.

_Dimensions._--Length of the shell 0.07 to 0.09, breadth 0.05 to 0.07.

_Habitat._--Tropical Atlantic, Station 352, surface.

6. _Medusetta spiralis_, n. sp.

Shell hemispherical, thorny, with wide open mouth. Apical horn straight, vertical, thorny, twice as long as the shell; feet cylindrical, three times as long as the shell, spirally convoluted around the vertical axis of the shell, with a series of recurved teeth on the abaxial margin.

_Dimensions._--Length of the shell 0.05, breadth 0.08.

_Habitat._--Central Pacific, Stations 271 to 272, surface.

7. _Medusetta craspedota_, n. sp. (Pl. 120, fig. 4).

Shell campanulate or nearly spherical, spiny, twice as broad as the constricted mouth, which is surrounded by a funnel-shaped truncate velum. Apical horn conical, straight, spiny, half as long as the shell. Feet strongly curved, longer than the shell, with a series of short conical spines on the abaxial side.

_Dimensions._--Length of the shell 0.06, breadth 0.06.

_Habitat._--North Pacific, Station 239, surface.

Genus 701. _Euphysetta_,[318] n. gen.

_Definition._--#Medusettida# with four articulate feet on the peristome, one odd very large, and three small or rudimentary feet.

The genus _Euphysetta_ agrees with the preceding _Medusetta_ in the possession of four articulate feet; but whilst these in the latter are of equal size and similar shape, in the former a single odd foot only is developed, and very large, whilst the three others are rudimentary and very small. _Euphysetta_ exhibits therefore the same relation to _Medusetta_ that the Euphysidæ (_Euphysa_, _Steenstrupia_, &c.) bear to the Sarsiadæ (_Codonium_, _Sarsia_), among the Hydromedusæ (compare my System der Medusen, 1879, vol. i. p. 12).

{1670}1. _Euphysetta staurocodon_, n. sp. (Pl. 118, fig. 2).

Shell ovate, nearly as broad as long, smooth, with an oblique, slender, conical, apical horn of the same length. The larger odd foot cylindrical, curved, somewhat longer than the shell, with three diverging branches at the distal end. The three smaller feet very short, representing the form of a regular rectangular cross.

_Dimensions._--Length of the shell 0.15, breadth 0.14.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

2. _Euphysetta hybocodon_, n. sp.

Shell ovate, one and one-third times as long as broad, smooth, with an oblique, stout, conical horn of half the length. The larger odd foot cylindrical, curved, twice as long as the shell, with a few pairs of short lateral branches and forked distal end. The three smaller feet half as long as the shell, thorny.

_Dimensions._--Length of the shell 0.16, breadth 0.12.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

3. _Euphysetta amphicodon_, n. sp. (Pl. 118, fig. 3).

Shell subspherical, smooth, with a short, oblique, conical, apical horn. The larger odd foot cylindrical, nearly straight, as long as the shell, with a few short lateral branches, at the distal end forked. The three smaller feet were in one specimen observed forked, in another (the specimen figured) replaced by nine small thorns.

_Dimensions._--Length of the shell 0.11, breadth 0.13.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

Genus 702. _Gazelletta_,[319] John Murray, 1876 (_in litteris_).

_Definition._--#Medusettida# with six articulate feet on the peristome.

The genus _Gazelletta_ is by far the most common of all Medusettida, and some species seem to be widely distributed, or even cosmopolitan. The number of species, too, is in this genus much larger than in all the other genera of this family. It differs from the latter in the possession of six feet, which number is very constant in the majority of species; in some species, however, single specimens are not rarely found which possess five or seven feet instead of six. Usually the six feet are rather regularly formed and disposed, and diverge downwards; but sometimes there is more or less {1671}irregularity in their shape and arrangement. In the majority of species the feet are very long, curved, and armed in a very various manner, so that four subgenera may be distinguished, according to the armatures.

Subgenus 1. _Gazellarium_, Haeckel.

_Definition._--Feet simple, smooth, without spines and without terminal branches.

1. _Gazelletta hexanema_, n. sp. (Pl. 120, fig. 5).

Shell hemispherical, smooth. Feet very long, cylindrical, straight, smooth, widely divergent, without terminal branches.

_Dimensions._--Length of the shell 0.03 to 0.04, breadth 0.06 to 0.07; length of the feet 0.1 to 0.2.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

2. _Gazelletta macronema_, n. sp. (Pl. 120, figs. 7, 8).

Shell hemispherical, smooth. Feet very long, cylindrical, smooth, in the basal part horizontally expanded, in the distal part strongly curved downwards, without terminal branches.

_Dimensions._--Diameter of the shell 0.1 to 0.12, length of the feet 1.2 to 1.6.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

3. _Gazelletta orthonema_, n. sp. (Pl. 120, fig. 10).

Shell hat-shaped, thorny. Feet cylindrical, straight, smooth, widely divergent, without terminal branches.

_Dimensions._--Diameter of the shell 0.12 to 0.16, length of the feet 0.3 to 0.5.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

4. _Gazelletta cyrtonema_, n. sp. (Pl. 120, fig. 9).

Shell hat-shaped, thorny. Feet cylindrical, smooth, widely diverging at the base, strongly curved and convergent in the distal part, often semicircular, without terminal branches.

_Dimensions._--Diameter of the shell 0.11 to 0.13, length of the feet 0.4 to 0.6.

_Habitat._--North Atlantic, Station 354, Canary Islands, surface.

Subgenus 2. _Gazellidium_, Haeckel.

_Definition._--Feet smooth, without lateral spines, but branched at the distal end, or with a bunch of terminal spines.

{1672}5. _Gazelletta furcata_, n. sp.

Shell flat, cap-shaped, smooth. Feet cylindrical, nearly straight, at the distal end forked, with two divergent, spinulate, terminal branches.

_Dimensions._--Length of the shell 0.12, breadth 0.3; length of the feet 0.6 to 0.8.

_Habitat._--Western Tropical Pacific, Station 224, surface.

6. _Gazelletta bifurca_, n. sp. (Pl. 120, fig. 6).

Shell cap-shaped, thorny. Feet nearly straight, widely divergent, cylindrical, smooth, at the distal end twice forked, with four divergent, terminal branches, each of which bears a spathillum with six to eight recurved teeth (sometimes, as in the specimen figured, five or six terminal branches instead of four).

_Dimensions._--Diameter of the shell 0.1, length of the feet 0.3 to 0.4.

_Habitat._--South Pacific, Station 288, surface.

7. _Gazelletta penicillata_, n. sp.

Shell campanulate, spiny. Feet cylindrical, strongly curved, smooth, with a bunch of twelve to twenty or more curved spines at the distal end.

_Dimensions._--Diameter of the shell 0.08, length of the feet 0.6.

_Habitat._--Central Pacific, Station 266, surface.

Subgenus 3. _Gazellonium_, Haeckel.

_Definition._--Feet spiny, armed with simple or branched lateral spines, and with terminal branches of the same shape.

8. _Gazelletta pectinata_, n. sp.

Shell flat, cap-shaped, thorny, three times as broad as high. Feet straight or slightly curved, cylindrical, widely divergent, with four longitudinal rows of short and simple conical spines, which are directed towards the distal end, and about as long as a single joint of the foot.

_Dimensions._--Length of the shell 0.16, breadth 0.5; length of the feet 1.5 to 2.0, breadth 0.03 to 0.05.

_Habitat._--North Atlantic, Færöe Channel (John Murray), Hebrides (Moebius).

9. _Gazelletta pinnata_, n. sp.

Shell hat-shaped, thorny. Feet cylindrical, strongly curved, pinnate, with two opposite longitudinal rows of simple conical spines, which are slightly curved, directed towards the distal end and opposed in pairs on about each third or fourth joint.

_Dimensions._--Diameter of the shell 0.3, length of the feet 1.2 to 1.5.

_Habitat._--South Atlantic, Station 325, depth 2650 fathoms.

{1673}10. _Gazelletta studeri_, n. sp. (Pl. 120, fig. 15).

Shell flat, cap-shaped, thorny. Feet widely divergent, nearly straight and horizontally expanded, with two alternate longitudinal rows of lateral spines, which arise perpendicularly from the foot, are simple, conical, slightly curved, and alternate on the succeeding joints. Ends of the feet constricted, with four to six spines in one row. Dedicated to Professor Studer.

_Dimensions._--Diameter of the shell 0.15, length of the feet 0.6 to 0.8.

_Habitat._--South Atlantic (east of Patagonia), Station 318, surface.

11. _Gazelletta schleinitzii_, n. sp. (Pl. 120, figs. 11, 12).

Shell hat-shaped, thorny. Feet cylindrical, nearly straight and horizontally expanded, with four longitudinal rows of equal lateral spines, which arise perpendicularly from the foot and bear at the end three short divergent teeth. The end of the arms bears three forked spines. I name this elegant species in honour of Captain Schleinitz, commander of the German ship "Gazelle," who conducted the deep-sea soundings during the years 1874 to 1876.

_Dimensions._--Diameter of the shell 0.12, length of the feet 0.6 to 0.8.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

12. _Gazelletta trispathilla_, n. sp. (Pl. 120, fig. 13).

Shell flat, cap-shaped, smooth. Feet cylindrical, nearly straight, widely divergent, with longitudinal rows of alternate spines, which arise perpendicularly from the foot and bear at the end three short divergent branches, each with a spathilla of six short teeth.

_Dimensions._--Diameter of the shell 0.2 to 0.25, length of the feet 1.2 to 1.5.

_Habitat._--North Pacific, Station 235 to 238, surface.

13. _Gazelletta robusta_, n. sp. (Pl. 120, fig. 14).

Shell flat, cap-shaped, thorny. Feet cylindrical, very stout, slightly curved, covered with short irregularly branched spines; their ends with a bunch of similar spines.

_Dimensions._--Diameter of the shell 0.6, length of the feet 2.5 to 3.3.

_Habitat._--Central Pacific, Stations 263 to 274, surface.

Subgenus 4. _Gazellusium_, Haeckel.

_Definition._--Feet spiny, armed with simple or branched lateral spines, and with larger terminal branches of a different shape.

{1674}14. _Gazelletta dendronema_, n. sp. (Pl. 120, fig. 16).

Shell hemispherical, thorny, with a broad, alveolate velum which bears irregular hollow thorns on the inside and on the free margin (fig. 16). Feet divergent, irregularly curved, with scattered arborescent lateral spines, which are irregularly branched, and bear at the distal end of each branch a small spathilla with four to six teeth. The distal ends of the feet are dichotomously branched, with stouter simple fork-branches.

_Dimensions._--Length of the shell 0.17, breadth 0.36; length of the feet 0.5 to 0.7.

_Habitat._--North Pacific, Station 252, surface.

15. _Gazelletta melusina_, n. sp. (Pl. 118, fig. 1).

Shell campanulate, spiny. Feet divergent, strongly curved, with scattered arborescent lateral spines, which are richly and dichotomously branched, with thin, simple, terminal branches. The distal ends of the feet bear three or four much larger and stouter branches, which are again dichotomously branched.

_Dimensions._--Length of the shell 0.2, breadth 0.15; length of the feet 0.5 to 0.8.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

Genus 703. _Gorgonetta_,[320] n. gen.

_Definition._--#Medusettida# with twelve articulate feet on the peristome, six ascending and six alternate descending.

The genus _Gorgonetta_ is the most highly developed of all hitherto observed Medusettida, and belongs to the most remarkable forms of Radiolaria. Its general shape is very similar to that of a larva of a _Geryonia_ or _Carmarina_, in which six interradial larval tentacles are directed upwards, six alternating perradial permanent tentacles downwards. The six ascending feet are in all the four species observed smaller, more or less branched, and armed with spathillæ. The six descending feet are much larger and covered with very elegant pencils, the single threads of which bear a double spathilla. The distal ends of the feet are forked or branched.

1. _Gorgonetta mirabilis_, n. sp. (Pl. 119, figs. 1-4).

Shell cap-shaped, flatly vaulted, or nearly hemispherical, about twice as broad as long, with smooth surface. Six ascending feet widely divergent, about twice as long as the breadth of the shell, nearly straight, arborescent, with numerous curved branches, each of which bears at the distal end a spathilla with four to six short recurved teeth (fig. 2). Six descending feet about twice as {1675}long as the six alternate ascending, nearly straight, covered with numerous elegant pencils. Each pencil is richly branched, with fifty to one hundred or more thread-like ramules, and each terminal ramule has two cruciate spathillæ, a larger proximal and a smaller distal (figs. 3, 4); the four recurved anchor-teeth of the proximal spathilla are twice as large as those of the distal. The distal end of each descending foot bears three or four very stout terminal branches, each of which is about as long as the shell and again trifurcate at the distal end.

_Dimensions._--Length of the shell 0.2 to 0.3, breadth 0.4 to 0.5.

_Habitat._--Tropical Atlantic, Stations 346 to 348, surface.

2. _Gorgonetta geryonia_, n. sp.

Shell hemispherical, twice as broad as long, with short scattered thorns on the surface. Twelve feet of similar shape to those in the preceding species, but differing in the following characters:--the six ascending feet are much smaller, about as long as the breadth of the shell, and each bears only six to twelve short branches; the six descending feet are about three times as long as the shell, more or less curved; their pencils much smaller, and the two spathillæ of each pencil-thread bear five anchor-teeth. The distal ends are more richly and irregularly branched.

_Dimensions._--Length of the shell 0.4, breadth 0.7.

_Habitat._--Indian Ocean (Cocos Islands), Rabbe, surface.

3. _Gorgonetta carmarina_, n. sp.

Shell flat, cap-shaped, three times as broad as long. Twelve feet similar in shape to those of the two preceding species, but more irregular in form and arrangement, and differing in the following characters:--the six ascending feet are nearly horizontally expanded, one and a half times as long as the breadth of the shell, with few short branches, each of which bears a spathilla with six recurved anchor-teeth. The six descending feet are about five times as long as the shell, irregularly curved, studded with numerous small pencils, each thread of which bears a double spathilla with six teeth. The distal ends are irregularly branched.

_Dimensions._--Length of the shell 0.2, breadth 0.7.

_Habitat._--South Pacific, Station 318, depth 2040 fathoms.

4. _Gorgonetta bisenaria_, n. sp.

Shell campanulate, similar to that of _Gazelletta melusina_ (Pl. 118, fig. 1), with smooth surface. Six ascending feet about as long as the shell, nearly straight, similar to those of _Gorgonetta mirabilis_ (Pl. 119, fig. 1). Six descending feet also similar to those of the latter, but shorter, about twice as long as the shell, strongly curved, studded with numerous small pencils, each thread of which has a double spathilla with three teeth. The distal end of each foot bears a whorl of six to eight irregular forked branches.

_Dimensions._--Length of the shell 0.5, breadth 0.4.

_Habitat._--Central Pacific, Station 263, surface.

{1676}Genus 704. _Polypetta_,[321] n. gen.

_Definition._--#Medusettida# with numerous (ten to twenty or more) articulate feet.

The genus _Polypetta_ comprises those Medusettida in which the number of feet is very large and not limited, usually twenty to thirty or more. The few specimens of this genus that have been observed are rather different; and it may be that only the two first species described in the following lines are true Medusettida; they possess the usual distinctly alveolate feet, and are derived from the similar _Medusetta_ or _Gazelletta_ simply by multiplication of the feet. The two other species, however (figured in Pl. 116, figs. 1, 2, as _Porospathis_), belong perhaps to another family of PHÆODARIA (Castanellida?); their shell-structure is peculiar and their feet not distinctly alveolate; they may therefore represent a peculiar genus _Porospathis_ (Haeckel, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, 1879, p. 5).

1. _Polypetta polynema_, n. sp.

Shell campanulate, thorny, about as long as broad, with slightly constricted mouth, similar to that of _Gazelletta orthonema_ (Pl. 120, fig. 10). Shell-wall hollow, with irregular polygonal alveoles. Peristome with a corona of eighteen divergent, curved, cylindrical feet of unequal size; six larger primary on the margin of the shell, the other twelve secondary, between the former, somewhat above the margins at different heights. The feet are two to three times as long as the shell, irregularly curved and distinctly alveolate, without appendages.

_Dimensions._--Length of the shell 0.12, breadth 0.11.

_Habitat._--Central Pacific, Station 266, surface.

2. _Polypetta alveolata_, n. sp.

Shell campanulate, thorny, about as long as broad, very similar to that of _Medusetta craspedota_ (Pl. 120, fig. 4). Shell-wall hollow, with subregular hexagonal alveoles. Peristome prolonged into a short funnel-shaped proboscis, twice as long as the similar velum of the latter. The velum is surrounded by a corona of eight larger and eight to twelve smaller feet; the larger are about as long as the shell, divergent, irregularly curved, thorny, and distinctly alveolate; the smaller feet are scattered above the latter and form an immediate transition to the small spines of the shell-surface.

_Dimensions._--Length of the shell 0.08, breadth 0.09.

_Habitat._--South Pacific, Station 284, surface.

{1677}3. _Polypetta tabulata_, n. sp. (Pl. 116, figs. 2, 2_a_, 2_b_).

_Porospathis tabulata_, Hæckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12.

Shell subspherical, with elegantly panelled or tabulate surface, composed of small triangular plates, which are separated by a network of prominent crests; at each nodal point of the network a small conical thorn arises (figs. 2_a_, 2_b_). Each triangular plate seems to contain a hollow alveole, which opens into the shell-cavity (?). On the surface of the shell are scattered numerous (thirty to forty or more), cylindrical, hollow, radial spines, which are straight or slightly curved, not distinctly alveolate, and increase in size towards the mouth. The aboral spines are scarcely one-third as long as the radius of the shell, whilst the oral spines are three times as long as its diameter. The proboscis of the constricted mouth is a hollow cylinder, longer than the shell-radius, and armed with a corona of fifteen to twenty slender bristle-shaped teeth. The position of this singular species in this family is doubtful.

_Dimensions._--Diameter of the shell 0.1 to 0.11, length of the peristome 0.07, breadth 0.02.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

4. _Polypetta mammillata_, n. sp. (Pl. 116, figs. 1, 1_a_).

_Porospathis mammillata_, Hæckel, 1879, Sitzungsb. med.-nat., Gesellsch. Jena, Dec. 12.

Shell subspherical, densely covered with numerous mammiliform hollow papillæ, between which are scattered single longer, hollow, radial spines; these are irregularly curved, cylindrical, without distinct alveoles; the twelve longest are two to three times as long as the shell, divergent in the oral direction, and surround the base of the peristome in two irregular alternate circles, each with six spines. The hollow papillæ of the surface, between which are placed numerous circular pores (or dimples?), open into the shell-cavity by a small pore (fig. 1_a_); they are perhaps reduced radial spines. The constricted peristome is conical and prolonged into an inversely conical proboscis, which is about as long as the radius of the shell; its dilated mouth is surrounded by a corona of slender, divergent, bristle-shaped teeth. The position of this species in the family Medusettida is doubtful; perhaps it is more closely allied to the Castanellida.

_Dimensions._--Diameter of the shell 0.12; length of the proboscis 0.08, breadth 0.03; length of the shorter spines 0.1, of the longest spines 0.3.

_Habitat._--North Pacific, Station 252, surface.

Family LXXX. #CASTANELLIDA#, Haeckel, 1879 (Pl. 113).

_Castanellida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--PHÆODARIA with a spherical or subspherical shell, exhibiting ordinary lattice-work, with circular or roundish pores. Radial spines without circles of basal pores. Mouth of the shell large, usually circular and armed with teeth. Central capsule excentric, placed in the aboral half of the shell-cavity.

{1678}The family #Castanellida# represents a common and widely distributed group of PHÆODARIA, which posses a very simple and uniform shell, viz., a simple lattice-sphere with radial spines and one simple mouth. It may therefore be easily confounded with the Coscinommida, or those #Sphæroidea# in which the shell is also a simple lattice-sphere armed with radial spines (_Astrosphærida simplicia_, p. 209). Indeed the shell of both groups is very similar, and differs in one important point only; the Castanellida constantly possess one larger opening in the shell-wall, the shell-mouth, which is either smooth or armed with a corona of teeth; in the Coscinommida, however, such a mouth is never present. The living specimens of both groups, and those shells in which the soft body is preserved, are very easily distinguished, since the shell encloses in the Coscinommida the central capsule and the transparent calymma only, whilst the latter, besides, in the Castanellida contains a voluminous dark brown or green mass of phæodella, the characteristic phæodium. A closer examination of the central capsule reveals in all Castanellida the typical operculum, the astropyle, with the proboscis of the PHÆODARIA, which is never present in any #Sphæroidea#.

The Castanellida are easily distinguished also from those similar PHÆODARIA in which the shell is also a lattice-sphere; the lattice-work is constantly quite simple, as in the similar Coscinommida, never composed of separated tangential pieces (as in the Aulosphærida), or of porcellanous structure, with basal circles of pores (as in the Circoporida), or of diatomaceous structure (as in the Challengerida). The gigantic Orosphærida, which also in part posses a simple lattice-sphere, differ from the Castanellida in the absence of the peculiar shell-mouth.

Though the Castanellida belong to the most common PHÆODARIA, and though the number of individuals, floating on the surface of the tropical seas, is extraordinarily great, their variety of forms is very small; the six genera distinguished in the following system differ only in very slight characters, and the majority of the species are very similar, and often hardly distinguishable. The seven species figured in Pl. 113 exhibit the most striking differences which I could distinguish among all the species observed. The shell usually has the characteristic appearance of a chestnut, a sphere covered with very numerous short radial spines or bristles. In the majority of species a certain number of longer thin radial spines is scattered over the surface; these are usually simple, rarely branched. The mouth of the shell, corresponding to the proboscis of the central capsule, and placed in the same radius, is either a quite simple larger opening with a smooth margin (figs. 3, 5, 7) or is armed with a corona of teeth (figs. 1, 6).

The size of the shell varies between 0.2 and 0.8 mm., and is usually between 0.3 and 0.5 mm. Its form is in the majority of species a geometrical sphere; rarely it is somewhat irregular, slightly ellipsoidal (prolonged in the axis of the mouth and proboscis), or polyhedral (by conical protuberances from the bases of the radial spines). {1679}The ideal fundamental form of the shell, however, is constantly monaxonian, since the place of the shell-mouth and of the proboscis of the capsule (both lying in one axis of the sphere), causes a principal axis to be different from all others. The longer radial spines, quite variable in number and disposition, are never arranged regularly or symmetrically, and therefore determine no constant axes.

The lattice-work of the spherical shell offers also but slight differences. It is usually more or less irregular, with circular or subcircular pores of unequal sizes. More rarely the network is perfectly regular, with equidistant circular pores of equal size, and sometimes these are surrounded by hexagonal frames (fig. 6), as in many #Sphæroidea#. More rarely the pores are perfectly irregular, roundish or sometimes polygonal, of unequal sizes and dissimilar forms (fig. 2). The size of the pores is very variable between 0.01 and 0.05, usually between 0.015 and 0.025. They are commonly somewhat broader than the bars between them, more rarely smaller. The substance of the shell-wall is in the the majority of Castanellida hyaline, transparent (as in the similar #Sphæroidea#); in some larger forms, however, a network of fine axial filaments is visible in the lattice (fig. 2), and sometimes this seems to be hollow, with an axial canal (as in the large Orosphærida). Such an axial filament or fine axial canal is usually visible in the larger radial spines. The shell-wall of the Castanellida, however, never exhibits that characteristic structure (with tangential needles in a cement-like fundamental substance), which we find in all Circoporida. The latter differ also in the constant presence of circles of large pores around the bases of the radial spines, which are never found in the Castanellida. The shell becomes usually stained more or less purple by carmine, and when burned by fire, becomes of a brown colour.

The inner surface of the shell is always quite smooth, the outer surface armed with numerous short and thin radial bristles. Sometimes these bristles or "by-spines" are very short, but never perfectly wanting. Usually their length is about one-third or one-fourth of the radius of the shell, often less, rarely more. They arise from the nodal points between every three or four neighbouring spines, and are commonly very thin and straight, pointed, with slightly thickened conical basis. Rarely they are directed not quite radially, but more or less obliquely.

The larger radial spines, which arise between the thin bristles or "by-spines" and may be opposed to the latter as "main-spines," are wanting in two genera only, in _Castanarium_ and _Castanella_ (Pl. 113, fig. 6). They are simple in _Castanidium_ (figs. 2, 5, 7) and _Castanissa_ (fig. 1), irregularly branched in _Castanopsis_ and _Castanura_ (figs. 3, 4). Their number and disposition is never regular nor symmetrical (as in the majority of #Sphæroidea#) and varies even in each single species. In general the number of main-spines varies between ten and forty (rarely less or more) usually between twenty and thirty. Their length is commonly about equal to the diameter of the shell, often somewhat shorter, rarely considerably longer. Their {1680}thickness is in the majority of species about equal to the diameter of one or two pores of the lattice. Sometimes they are much stronger, rarely thinner.

The form of the radial main-spines is not very variable, usually it is cylindrical or cylindro-conical, rarely angular, prismatic or pyramidal. Sometimes they are straight (perfectly radial), at other times more or less irregularly curved. Usually they are simple, rarely branched; the branches are always very irregular and exhibit a remarkable tendency to unite by concrescence (figs. 3, 4). Some thicker forms of spines exhibit a remarkable structure, the surface being covered with small dimples and spinules between them (fig. 1); sometimes the dimples are hexagonal (fig. 5_a_). In the axis of the thicker spines there is often visible the same axial filament or funicle which we find in many other PHÆODARIA, more rarely a hollow axial canal.

The mouth of the shell is usually circular, more rarely polygonal or irregularly roundish (fig. 2). It is either quite smooth (fig. 3, 5, 7) or armed with a corona of strong teeth (figs. 1, 4, 6). These teeth are different from the other spines of the shell; they are much thicker than the radial bristles, and shorter than the main-spines. Their number varies between three and twenty, usually between five and seven. They are usually parallel to the main axis, which is determined by the excentric position of the mouth and the centre of the sphere (figs. 1, 6). The teeth are usually conical, more or less irregular in size and form, more rarely of equal size. The corona of teeth is usually sharply separated from the surrounding lattice-work of the shell, but has no influence on its regular spherical form.

The _central capsule_ of the Castanellida immediately determines beyond doubt their true PHÆODARIAN nature; it lies excentrically in the cavity of the enclosing shell, and is surrounded at the oral pole by the large and dark phæodium. The latter covers the radiate operculum of the capsule membrane and the tubular proboscis, which arises from it and is directed towards the shell mouth. Usually the diameter of the spherical central capsule is about one-third of the shell diameter, rarely one-quarter only, and in a few cases it attains nearly its half. The calymma, therefore, is larger than the capsule, and fills up the whole cavity of the shell which is not occupied by the latter. The greater part of the calymma again is filled up by the dark green or brown, sometimes black phæodella, the roundish granules which compose the voluminous non-transparent phæodium. Sometimes the latter proceeds through the mouth and is partially placed outside the shell (fig. 5).

The astropyle, or the main-opening of the central capsule, is placed on the oral pole of its main axis, while its radiate operculum and the tubular proboscis arising from it possess the same structure as in the other PHÆODARIA. But the two lateral parapylæ or accessory openings which are present in the majority of the latter seem to be absent in the Castanellida as well as in the Medusettida and the Challengerida. I could never observe a trace of them. The proboscis is a small cylindrical tube and is directed towards the {1681}mouth of the shell, therefore placed in its main axis; it is usually quite hidden in the dark phæodium, which occupies the oral half of the shell-cavity, whilst the capsule lies in the aboral half. The large nucleus of the central capsule and its double membrane present the same characters as in the other PHÆODARIA.

_Synopsis of the Genera of Castanellida._

------------------------------------------------------------------------- No long radial main-spines (in addition to the constant short bristles of the shell-surface). ------------------------------------------------------------------------- Mouth smooth, 705. _Castanarium_.

Mouth dentate, 706. _Castanella_. ------------------------------------------------------------------------- Long radial main-spines scattered between the short constant bristles of the shell-surface. ------------------------------------------------------------------------- { Mouth smooth, 707. _Castanidium_. Main spines simple. { { Mouth dentate, 708. _Castanissa_.

{ Mouth smooth, 709. _Castanopsis_. Main spines branched. { { Mouth dentate, 710. _Castanura_.

Genus 705. _Castanarium_,[322] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# without radial main-spines, with a smooth mouth.

The genus _Castanarium_ is the simplest form of all the Castanellida, and may be regarded as the common ancestral form of this family. The simple spherical shell has a smooth, toothless mouth and no larger radial spines; it is densely studded with the simple, radial bristles, which are common to all Castanellida. The shell therefore is very similar to those species of the Astrosphæride _Acanthosphæra_, which represent the subgenus _Rhapidococcus_ (compare above, p. 210, Pl. 26, fig. 3); it differs from the latter in the possession of the shell-mouth, which is absent in all #Sphæroidea#.

1. _Castanarium darwini_, n. sp.

Pores regular, circular, hexagonally framed, three times as broad as the bars. Radial bristles half as long as the radius.

_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.03.

_Habitat._--South Atlantic (east of Patagonia), Station 318, depth 2040 fathoms.

{1682}2. _Castanarium hookeri_, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars. Radial bristles one-third as long as the radius.

_Dimensions._--Diameter of the shell 0.55, of the pores 0.025.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.

3. _Castanarium lyelli_, n. sp.

Pores regular, circular, without hexagonal frames, of the same breadth as the bars. Radial bristles twice as long as the diameter of one pore.

_Dimensions._--Diameter of the shell 0.24, of the pores 0.015.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.

4. _Castanarium lubbocki_, n. sp.

Pores irregularly roundish, about of the same breadth as the roundish, non-crested bars. Radial bristles one-third as long as the radius.

_Dimensions._--Diameter of the shell 0.36, of the pores 0.01 to 0.02.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

5. _Castanarium huxleyi_, n. sp.

Pores irregularly polygonal, two to three times as broad as the bars, separated by prominent polygonal crests. Radial bristles half as long as the radius.

_Dimensions._--Diameter of the shell 0.45, of the pores 0.02 to 0.05.

_Habitat._--South Pacific (off Australia), Station 165, surface.

Genus 706. _Castanella_,[323] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# without radial main-spines, with a dentate mouth.

The genus _Castanella_ comprises the most common and most widely distributed species of Castanellida. It agrees in general shape with its ancestral form, the preceding _Castanarium_, differing from it only in the possession of strong teeth, which form a corona around the mouth.

{1683}1. _Castanella wyvillei_, n. sp. (Pl. 113, fig. 6).

Pores regular, circular, of equal size, hexagonally framed, of the same breadth as the bars. Radial bristles twice as long as the diameter of one pore. Mouth with five to six parallel, conical strong teeth, which are twice as long as a bristle (fig. 6_a_).

_Dimensions._--Diameter of the shell 0.5 to 0.7, of the pores 0.02 to 0.03.

_Habitat._--North Pacific, Stations 252 to 256, surface.

2. _Castanella thomsoni_, n. sp.

Pores regular, circular, of equal size, hexagonally framed, twice as broad as the bars. Radial bristles about as long as the diameter of one pore. Mouth with four strong, conical teeth, forming a regular cross, four times as long as a bristle.

_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.03.

_Habitat._--South Pacific, Stations 295 to 298, surface.

3. _Castanella campbelli_, n. sp.

Pores regular, circular, hexagonally framed, three times as broad as the bars. Radial bristles half as long as the radius of the shell. Mouth with a coronet of eight conical, parallel teeth, of the same length as the bristles, but four to six times as thick.

_Dimensions._--Diameter of the shell 0.4 to 0.45, of the pores 0.025.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

4. _Castanella sloggetti_, n. sp.

Pores subregular, circular, without frames, of different sizes, about twice as broad as the bars. Radial bristles three times as long as one pore. Mouth with five or six strong, conical teeth, twice as long as the bristles.

_Dimensions._--Diameter of the shell 0.3 to 0.36, of the pores 0.02 to 0.03.

_Habitat._--Tropical Atlantic, Stations 347 to 349, surface.

5. _Castanella balfouri_, n. sp.

Pores irregular, roundish, two to three times as broad as the bars. Bristles about one-fourth as long as the radius. Mouth with four strong conical teeth, forming a cross, somewhat longer and much thicker than the bristles.

_Dimensions._--Diameter of the shell 0.22 to 0.28, of the pores 0.01 to 0.02.

_Habitat._--North Pacific, Stations 240 to 245, surface.

{1684}6. _Castanella channeri_, n. sp.

Pores irregular, roundish, two to four times as broad as the bars. Bristles nearly half as long as the radius. Mouth with seven to nine short conical teeth, shorter than the bristles, but much thicker.

_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.02 to 0.025.

_Habitat._--North Atlantic, Stations 352 to 354, surface.

7. _Castanella horstoni_, n. sp.

Pores irregular, polygonal, three to four times as broad as the bars. Bristles about as long as the radius. Mouth with six stout pyramidal teeth, which are scarcely one-third as long as the radius.

_Dimensions._--Diameter of the shell 0.55, of the pores 0.02 to 0.025.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

Genus 707. _Castanidium_,[324] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida#, with simple radial main-spines and a simple smooth mouth.

The genus _Castanidium_ agrees with its ancestral form _Castanarium_ in the simple shape of the smooth and toothless mouth, but differs from it in the possession of long radial main-spines, which are scattered between the constant radial bristles or by-spines of the surface. The shell agrees therefore in its general shape with the Astrosphæride _Heliosphæra_, as defined above (p. 217, Pl. 26, fig. 9), but differs from it in the possession of the shell-mouth wanting in all #Sphæroidea#.

1. _Castanidium willemoesi_, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars. Bristles three times as long as the diameter of one pore. Radial main-spines straight, conical, smooth, as long as the radius.

_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.012 to 0.016.

_Habitat._--Central Pacific, Station 263 to 274, surface.

2. _Castanidium wildi_, n. sp.

Pores regular, circular, hexagonally framed, of the same breadth as the bars. Bristles twice as long as one pore. Radial main-spines straight and short, cylindrical, with dimpled surface (as in Pl. 113, fig. 1), as broad as one pore and as long as the diameter of the shell.

_Dimensions._--Diameter of the shell 0.66, of the pores 0.045.

_Habitat._--South Pacific, Station 297, surface.

{1685}3. _Castanidium buchanani_, n. sp. (Pl. 113, fig. 7).

Pores regular, circular, without frames, twice as broad as the bars, of variable size. Bristles five to six times as long as one pore. Radial main-spines numerous, straight, slender, cylindrical, about as long as the diameter of the shell.

_Dimensions._--Diameter of the shell 0.25 to 0.3, of the pores 0.012 to 0.02.

_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.

4. _Castanidium murrayi_, n. sp. (Pl. 113, figs. 5, 5_a_).

Pores subregular, circular, without frames, three times as broad as the bars. Bristles three times as long as one pore. Radial main-spines cylindrical, stout, irregularly curved, longer than the shell-diameter, covered with longish hexagonal dimples, which are separated by a network of prominent crests (fig. 5_a_).

_Dimensions._--Diameter of the shell 0.4 to 0.5, of the pores 0.02 to 0.025.

_Habitat._--North Atlantic, Station 352 to 354, surface.

5. _Castanidium aldrichi_, n. sp.

Pores subregular, circular, without frames, of variable size, about as broad as the bars. Bristles four times as long as one pore. Radial main-spines conico-cylindrical, irregularly curved, straight, about as long as the radius. (The conical base of the spines is inflated and fenestrated, therefore the shell is nearly polyhedral.)

_Dimensions._--Diameter of the shell 0.35 to 0.4, of the pores 0.012 to 0.015.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

6. _Castanidium bromleyi_, n. sp.

Pores irregular, roundish, two to four times as broad as the bars. Bristles half as long as the radius. Radial main-spines cylindrical, straight, slender, longer than the shell-diameter.

_Dimensions._--Diameter of the shell 0.22 to 0.26, of the pores 0.006 to 0.02.

_Habitat._--Indian Ocean and Southern Pacific, Stations 162 to 169, surface.

7. _Castanidium bethelli_, n. sp.

Pores irregular, roundish or polygonal, two to three times as broad as the bars. Bristles one-third as long as the radius. Radial main-spines conico-cylindrical, irregularly curved, with dimpled surface, somewhat longer than the radius.

_Dimensions._--Diameter of the shell 0.5 to 0.6, of the pores 0.015 to 0.03.

_Habitat._--North Pacific, Stations 235 to 245, surface.

{1686}8. _Castanidium moseleyi_, n. sp. (Pl. 113, fig. 2).

Pores irregular, roundish or polygonal, two to four times as broad as the bars. Bristles about as long as the diameter of one pore, or a little longer. Radial main-spines cylindrical, irregularly curved, somewhat longer than the diameter of the shell; their base is more or less inflated and fenestrated, therefore the shell is nearly polyhedral.

_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.01 to 0.04.

_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.

Genus 708. _Castanissa_,[325] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# with simple radial main-spines and a dentate mouth.

The genus _Castanissa_ agrees with the preceding _Castanidium_ in the possession of large radial main-spines, scattered between the numerous bristles or by-spines of the surface; but it differs from it in the possession of teeth around the mouth, identical with those of _Castanella_; it may be derived therefore either from the latter by development of main-spines, or from the former by formation of teeth.

1. _Castanissa challengeri_, n. sp. (Pl. 113, fig. 1).

Pores regular, circular, three times as broad as the bars. Bristles one-fourth as long as the radius. Radial main-spines (about twelve) very stout, straight, cylindrical, at the distal end conical, pointed, with dimpled surface, about half as long as the radius. Mouth very large, circular, about one-third as broad as the shell, with a corona of twelve to sixteen very large, triangular, parallel teeth.

_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.03.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

2. _Castanissa pearceyi_, n. sp.

Pores regular, circular, twice as broad as the bars. Bristles half as long as the radius. Radial main-spines (about twenty) slender, cylindrical, smooth, irregularly curved, about as long as the radius. Mouth large, half as broad as the radius, with a corona of ten to twelve irregular, slender teeth.

_Dimensions._--Diameter of the shell 0.5 to 0.6, of the pores 0.02.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

{1687}3. _Castanissa richardsi_, n. sp.

Pores subregular, circular, about as broad as the bars. Bristles twice as long as one pore. Radial main-spines (about twenty) slender, cylindrical, irregularly curved, with dimpled surface (like those in Pl. 113, fig. 5_a_). Mouth with a corona of six stout, parallel, triangular teeth.

_Dimensions._--Diameter of the shell 0.3 to 0.35, of the pores 0.015.

_Habitat._--North Atlantic, Station 354, surface.

4. _Castanissa crosbiei_, n. sp.

Pores irregular, roundish, two to three times as broad as the bars. Bristles one-third as long as the radius. Radial main-spines very numerous, straight, cylindrical, smooth, about as long as the diameter of the shell. Mouth with ten or twelve irregular, conical, parallel teeth.

_Dimensions._--Diameter of the shell 0.28, of the pores 0.01 to 0.015.

_Habitat._--North Pacific, Stations 231 to 235, surface.

5. _Castanissa macleani_, n. sp.

Pores irregular, roundish or polygonal, two to four times as broad as the bars. Bristles about one-fourth as long as the radius. Radial main-spines numerous, straight, conical, stout, with dimpled surface, shorter than the radius. Mouth with six to eight irregular conical teeth.

_Dimensions._--Diameter of the shell 0.32, of the pores 0.012 to 0.024.

_Habitat._--Tropical Pacific, Station 268, depth 2900 fathoms.

6. _Castanissa hoylei_, n. sp.

Pores irregular, polygonal, two to three times as broad as the bars. Bristles nearly half as long as the radius. Radial main-spines (about thirty) very long and thin, cylindrical, irregularly curved, at the conical base inflated and fenestrated; shell therefore slightly polyhedral. Mouth with five strong conical teeth.

_Dimensions._--Diameter of the shell 0.35 to 0.4, of the pores 0.02 to 0.03.

_Habitat._--North Pacific, Station 245 to 250, surface.

Genus 709. _Castanopsis_,[326] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# with branched radial main-spines and a simple smooth mouth.

The genus _Castanopsis_ differs from its ancestral form _Castanidium_ in the ramification of the radial main-spines; the branches are usually very irregular and often partly {1688}confluent. The shell is very similar to the Astrosphæride _Cladococcus_ (compare above p. 223, Pl. 27), but differs from it in the possession of the shell-mouth, absent in all #Sphæroidea#.

1. _Castanopsis naresi_, n. sp. (Pl. 113, fig. 3).

Pores subregular, circular, about twice as broad as the bars. Bristles twice as long as one pore. Radial main-spines somewhat shorter than the diameter of the shell, straight, cylindrical, in the proximal half simple, in the distal half irregularly branched, each with ten to twelve partly confluent branches.

_Dimensions._--Diameter of the shell 0.6 to 0.7, of the pores 0.02 to 0.03.

_Habitat._--Tropical Atlantic, Station 347 to 349, surface.

2. _Castanopsis macleari_, n. sp.

Pores irregular, roundish, two to four times as broad as bars. Bristles half as long as the radius. Radial main-spines about as long as the radius, stout and straight, cylindrical, forked at the distal end, with two or three unequal fork-branches.

_Dimensions._--Diameter of the shell 0.42, of the pores 0.015 to 0.03.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

3. _Castanopsis fergusoni_, n. sp.

Pores irregular, roundish or polygonal, about as broad as the bars. Bristles three times as long as one pore. Radial main-spines somewhat longer than the diameter of the shell, cylindrical, with irregular and partly confluent lateral branches (similar to Pl. 113, fig. 4_a_).

_Dimensions._--Diameter of the shell 0.55, of the pores 0.012 to 0.016.

_Habitat._--North Atlantic, Station 354, surface.

Genus 710. _Castanura_,[327] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# with branched radial main-spines and a dentate mouth.

The genus _Castanura_ differs from the preceding _Castanopsis_ in the possession of a corona of teeth surrounding the mouth, similar to that of _Castanissa_. It differs from the latter in the ramification of the radial main-spines, wherein it agrees with the former. _Castanura_ may therefore be derived either from _Castanissa_ by ramification of the main-spines, or from _Castanopsis_ by development of teeth around the mouth.

{1689}1. _Castanura tizardi_, n. sp. (Pl. 113, fig. 4, 4_a_).

Pores regular, circular, without hexagonal frames, twice as broad as the bars. Bristles twice as long as one pore. Radial main-spines somewhat longer than the radius, straight, very stout, with irregular lateral branches, which are partly confluent. Mouth with six strong conical teeth.

_Dimensions._--Diameter of the shell 0.6, of the pores 0.03.

_Habitat._--Tropical Atlantic, Station 346, surface.

2. _Castanura havergali_, n. sp.

Pores regular, circular, hexagonally framed, as broad as the bars. Bristles three times as long as one pore. Radial main-spines as long as the shell-diameter, in the basal half simple, in the distal half with irregular, not confluent, lateral branches. Mouth with ten to twelve irregular, parallel, conical teeth of different sizes.

_Dimensions._--Diameter of the shell 0.5, of the pores 0.045.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

3. _Castanura swirei_, n. sp.

Pores regular, circular, hexagonally framed, as broad as the bars. Bristles half as long as the radius. Radial main-spines straight, longer than the shell-diameter; on the distal end with a few irregular, confluent, lateral branches. Mouth with six larger and six alternate smaller, parallel, conical teeth.

_Dimensions._--Diameter of the shell 0.28, of the pores 0.015.

_Habitat._--North Pacific, Station 253, surface.

4. _Castanura carpenteri_, n. sp.

Pores irregular, roundish, twice to four times as broad as the bars. Bristles about as long as the largest pores. Radial main-spines irregularly curved, longer than the shell-diameter, with inflated and fenestrated conical base; in the distal half irregularly branched, with simple, not confluent, lateral branches. Mouth with six to nine irregular, strong, conical teeth.

_Dimensions._--Diameter of the shell 0.3, of the pores 0.012 to 0.025.

_Habitat._--South Atlantic, Station 331, depth 1715 fathoms.

Family LXXXI. #CIRCOPORIDA#, Haeckel, 1879 (Pls. 114-117).

_Circoporida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--PHÆODARIA with a spherical or polyhedral shell, exhibiting a peculiar solid porcellanous structure, with a stellate circle of radial pores around the base of the hollow radial spines. Mouth usually with teeth. Surface of the shell {1690}tabulate, panelled or dimpled. Central capsule excentric, placed in the aboral half of the shell-cavity.

The family #Circoporida# comprises those PHÆODARIA in which the simple spherical or polyhedral shell exhibits a peculiar porcellanous structure, possesses a simple mouth, and is particularly distinguished by the constant character denoted by their name, viz., by circles of pores surrounding the base of the radial spines. It agrees in these striking peculiarities with the following family, the Tuscarorida, but differs from them essentially by the spherical or polyhedral form of the shell, which is never ovate, with the main axis prolonged. The radial spines, variable in number, are regularly or symmetrically disposed in all Circoporida, whilst they are arranged around the poles of the main axis in all Tuscarorida. Whilst the latter are always extremely large, more than a millimeter in size, the former are much smaller and never reach the diameter of a millimeter. The number of genera and species in this family is not large, and the majority are very rare, but they belong to the most remarkable Radiolaria by the peculiar structure, as well as by the geometrical regularity of the polyhedral shell.

The Circoporida may be divided into two different subfamilies, the Circogonida and the Haeckelinida. The latter are represented by the single genus _Haeckeliana_ (Pl. 114), and possess a spherical shell with numerous small dimples between the circles of pores, and numerous simple radial spines which do not exhibit a regular arrangement. The Circogonida, on the other hand, comprise all other genera (Pls. 115-117) and possess a panelled shell with polygonal plates, and a certain number of radial spines, which are regularly disposed on the corners of the polyhedral shell, and usually armed with verticillate bristles and terminal forks or spathillæ. Perhaps the Circogonida and Haeckelinida may be better considered as two separate families.

The geometrical fundamental form of the shell is in the Circoporida of the highest interest, since it exhibits regular proportions, which are very rare in other organic forms, generally some rare forms of regular polyhedrons. The shell in all members of this family belongs to that group of geometrical forms which I have called in my General Morphology "_Polyaxonia_" (vol. i., 1866, pp. 406-416). The shell therefore is constantly an "endospherical polyhedron," _i.e._, a polyhedron, all the corners of which lie in a spherical surface. The corners are always indicated by the bases of the radial spines arising from the surface of the shell and marking its axes, and it is immaterial whether the shell itself is a true polyhedron or a sphere; for in the latter case also the radial spines mark the axes of the polyhedron.

The six genera which we here distinguish among the Circoporida, represent six different fundamental forms. _Circoporus_ (Pl. 115, figs. 1-3; Pl. 117, figs. 5, 6) possesses six radial spines, opposite in pairs in three diameters, perpendicular one to another; it agrees therefore with the Cubosphærida (p. 169, Pls. 21-25) and {1691}represents the regular octahedron, with eight congruent triangular faces and six corners. It has the same form as the well-known antheridia of Chara (Gener. Morphol., vol. i. p. 412). _Circogonia_ (Pl. 115, figs. 8-10; Pl. 117, fig. 1) exhibits twelve radial spines, opposite in pairs in six equidistant diameters. The surface of the shell is divided into twenty equal and equilateral triangles, and agrees therefore with the regular icosahedron. The same form appears also in some forms of _Aulosphæra_, and in several Astrosphærida (Gener. Morphol., vol. i. p. 411). _Circorrhegma_ (Pl. 117, fig. 2) possesses a regular shell with twelve equal pentagonal faces and twenty equidistant corners, from which arise twenty regularly disposed radial spines. It represents therefore the regular "pentagonal dodecahedron," the same remarkable form which is found in some Astrosphærida, and in the pollen-grains of some plants, _e.g._, _Bucholzia maritima_, _Fumaria spicata_, _Polygonum amphibium_, &c. (Gener. Morphol., vol. i. p. 412, Taf. ii. fig. 18).

The three genera of Circoporida mentioned therefore represent three different forms of regular polyhedrons, in the exact mathematical sense, viz., _Circoporus_, the regular octahedron, _Circogonia_, the regular icosahedron, and _Circorrhegma_, the regular dodecahedron. In each of these three regular forms all the faces, edges, and corners are equal. The remaining three genera of Circoporida represent, however, three forms of subregular or irregular endospherical polyhedra, which are not perfectly regular. _Circospathis_ (Pl. 115, figs. 4-7; Pl. 117, fig. 3) is a rather common form, and constantly possesses nine symmetrically disposed radial spines; the shell is either spherical or polyhedral, with fourteen triangular faces and thirty edges; the nine spines lie in three meridional planes, which are crossed at equal angles (three equidistant spines in each plane). We call this remarkable form the tetradecahedron; it appears also in some Astrosphærida (_e.g._, in _Haliomma echinaster_, figured in my Monograph, Taf. xxiv. fig. 1). _Circostephanus_ (Pl. 116, fig. 3) exhibits a subregular polyhedral shell with a variable number of triangular faces and of radial spines (twenty-four to forty or more). _Circostephanus sexagenarius_ possesses sixty triangular equilateral faces, which are disposed in twelve pentagonal groups (each with five faces), so that the shell seems to be derived from a regular pentagonal dodecahedron, the twelve regular faces of which are divided each into five congruent triangles. From its corners arise thirty-two radial spines (twelve from the central points of the pentagons, twenty from the meeting corners of every three pentagons). In other cases the number of faces and radial spines seems to be larger and their arrangement more irregular. The same may be said of _Haeckeliana_, in which the dimpled shell is constantly spherical, and possesses a variable number of radial spines, from sixteen to fifty-five (usually between thirty and forty).

The structure of the shell in the Circoporida is the same as in the Tuscarorida, of a peculiar porcellanous nature. The shell-wall is very thick, more or less opaque, and in direct light whitish or yellowish. Its surface is dimpled, with numerous small, circular, {1692}roundish or polygonal dimples in _Haeckeliana_ (Pl. 114, figs. 1-6). In the Circogonida, however, the surface is panelled, with regular or irregular polygonal plates, often separated by high prominent crests (Pl. 115, figs. 4-9, &c.). Numerous simple thin needles of silica lie tangentially disposed and irregularly scattered in the porcellanous or cement-like substance of the thick shell-wall. Under a strong lens this substance appears finely punctate, being probably pierced by numerous very fine pores. The surface of the shell is therefore minutely roughened, and often appears quite black under the microscope, by the adhesion of innumerable fine air-bubbles. In all Circoporida, as well is in the Tuscarorida, the porcellanous shell has not the perfect transparency of the purely siliceous shells of other Radiolaria; its refractive power is somewhat different from the latter; it becomes deeply stained by carmine and browned by fire, and seems therefore to consist of a peculiar carbonic silicate.

The shell in all Circoporida exhibits a simple, excentric mouth, which corresponds to the main osculum of the central capsule. The excentric position of this shell-mouth has no influence on the regular form of the shell. The mouth is either circular or polygonal, usually about as large as a basal circle of pores. It is always armed with prominent conical or pyramidal teeth, the number of which is variable and seems to depend partly upon the number of the shell-faces or the radial spines. _Circoporus_ has usually four cruciate teeth (Pl. 115, fig. 1; Pl. 117, figs. 4, 5). _Circorrhegma_ exhibits a pentagonal mouth with five teeth (Pl. 117, fig. 2). _Circogonia_ possesses a hexagonal mouth with six teeth (Pl. 115, fig. 8; Pl. 117, fig. 1). _Circospathis_ has no constant number; some species have five teeth (Pl. 115, fig. 4), others four (Pl. 115, fig. 10), others nine (Pl. 117, fig. 3_a_). _Circostephanus_ is also variable; one species exhibits eight teeth (Pl. 116, fig. 3_a_), another ten, another twelve. In _Haeckeliana_ (Pl. 114, fig. 3) the teeth are smaller and more numerous. Usually the teeth arise vertically from the surface of the shell and are spinulate; more rarely their points are directed towards the centre of the mouth. Sometimes numerous thin needles arise between the teeth (Pl. 115, fig. 10).

The radial spines of the Circoporida are tubular, usually cylindrical and conical at the thickened base, more rarely prismatic or slenderly pyramidal, with three or more edges; sometimes the edges are spirally wound around the axis (Pl. 115, fig. 6). In the majority of species their length is about equal to the diameter of the shell; often they are somewhat shorter, more rarely longer. Their tubular structure is always the same as in the Tuscarorida; the wall of the tube is thick, and in the axis of its cavity lies an axial cord or funicle, which is connected with the wall by numerous horizontal, simple, or branched threads (Pl. 115, figs. 6, 7). The axial funicle itself is either a simple thread of silica, or a strand, composed of three to fifteen or more filaments, which are closely twisted like a rope around the axis of the spine, and arise separately from the bridges between the pores of the basal circle (Pl. 115, figs. 7, 9). The number of {1693}pores in these circles is very variable, commonly from three to nine, sometimes twelve to fifteen or more; their form is usually irregularly ovate (Pl. 115, figs. 7, 9). The bridges between the pores usually bear numerous siliceous threads or bristles, which are curved downwards or upwards (Pl. 115, figs. 4-6). Sometimes the spines are entirely covered with similar bristles or cilia (Pl. 117, figs. 2-5), more rarely with regular verticils of lateral branches (Pl. 117, fig. 6).

The distal ends of the radial spines are simple in _Haeckeliana_ (Pl. 114), whilst in the other Circoporida they are usually (or perhaps constantly) either forked or armed with a verticil of terminal branches. When the spines are simply forked, their two terminal branches lie in certain meridional planes (Pl. 117, fig. 5). The same is probably the case when they bear three divergent branches (Pl. 115, figs. 1, 2), or four crossed branches (Pl. 117, figs. 4, 6). The larger species usually bear a corona of five curved branches disposed around the distal apex of each spine (Pl. 116, fig. 3; Pl. 117, figs. 1, 2). Sometimes the formation of these coronas is twice or more often repeated, so that the spines appear verticillate.

The _central capsule_ of the Circoporida (Pl. 115, fig. 8; Pl. 117, fig. 6) is usually about half as large as the enclosing shell, and lies excentrically in that half of its cavity which is remote from the shell-mouth (Pl. 115, fig. 8). The other half (near the mouth) is filled up by the cap-shaped, dark phæodium. The proboscis, or the central tubule of the astropyle, is hidden in the axis of the blackish phæodium, and is directed towards the mouth of the shell; it is often S-shaped, more or less curved. The circular radiate operculum of the astropyle, placed on the base of the proboscis, exhibits numerous branched radial ribs, and closes the main-opening like the lid of a tea-kettle (Pl. 115, fig. 3). The number of the parapylæ, or the accessory openings of the capsule, which in the majority of PHÆODARIA is two, seems to be usually increased in the Circoporida. In _Circoporus_ the capsule seems to posses six and in _Circospathis_ nine secondary openings, and therefore there is some probability that each circle of pores on the base of a radial spine corresponds to a secondary opening of the capsule. In _Haeckeliana_, however (Pl. 114), I could observe no parapylæ at all. These accessory openings are always very small in the Circoporida, and may be easily overlooked. Furthermore, the number of observations respecting this difficult point is too small, and their certainty not satisfactory; it requires therefore further accurate examination, as also does the whole central capsule of the Circoporida.

The numerous and remarkable characters of shape and structure, which we have described above as occurring in the Circoporida, are also found in the following closely allied family, the Tuscarorida; all the species are inhabitants of great depths. Perhaps it may therefore be more convenient to separate these two families from the other PHÆOGROMIA as a peculiar order, under the name PHÆOCALPIA.

{1694}_Synopsis of the Genera of Circoporida._

------------------------------------------------------------------------- I. Subfamily Circogonida. Shell spherical or polyhedral with panelled structure and polygonal plates. A certain number of radial spines are geometrically disposed. ------------------------------------------------------------------------- Shell octahedral (or spherical), Six radial spines, 711. _Circoporus_.

Shell tetradecahedral, Nine radial spines, 712. _Circospathis_.

Shell icosahedral, Twelve radial spines, 713. _Circogonia_.

Shell dodecahedral, Twenty radial spines, 714. _Circorrhegma_.

Shell polyhedral, Twenty-four to forty or more radial spines, 715. _Circostephanus_. ------------------------------------------------------------------------- II. Subfamily Haeckelinida. ------------------------------------------------------------------------- Shell spherical, with dimpled structure, and a variable number of radial spines (without polygonal plates), 716. _Haeckeliana_.

Subfamily 1. CIRCOGONIDA, Haeckel.

_Definition._--#Circoporida# with panelled shell, composed of polygonal plates. The shell is usually polyhedral, more rarely spherical, and the radial spines are usually (or perhaps constantly) branched and regularly arranged.

Genus 711. _Circoporus_,[328] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Circoporida# with a spherical or regularly octahedral shell, composed of eight congruent, triangular plates, with six corners from which arise six radial spines, opposite in pairs in three diameters, perpendicular one to another.

The genus _Circoporus_, the simplest among the Circoporida, is distinguished by the regular octahedral form of the shell, with the three equal axes of the regular crystalline system perpendicular one to another. Six equal radial spines, arising from the six corners, lie opposite in pairs in those three dimensive axes. The eight equal triangular faces of the octahedron are sometimes plane, sometimes concave or convex, and sometimes the shell becomes spherical. In this case it becomes very similar to the Hexastylida among the #Sphæroidea#.

1. _Circoporus sexfurcus_, Haeckel (Pl. 117, fig. 5).

_Challengeria_ sp., John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv. pl. xxiv. fig. 5.

Shell spherical, covered with irregular, polygonal plates. Six radial spines shorter than the diameter of the shell, covered with thin curved bristles, in the proximal half cylindrical, in the distal half forked, each with two equal curved fork-branches. Around the ciliated base of each spine a {1695}corona of twelve to sixteen pores surrounded by a circle of numerous, curved, longer bristles. Mouth cruciform, with four triangular, convergent teeth.

_Dimensions._--Diameter of the shell 0.55, length of the spines 0.4.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

2. _Circoporus hexastylus_, n. sp. (Pl. 117, fig. 4).

Shell regularly octahedral, with eight plane, congruent, triangular faces, which are covered with a very delicate network of small, regular, hexagonal plates. Six radial spines as long as the radius of the shell, four-sided pyramidal, simple, in the basal half covered with numerous curved bristles. Around the base of each spine a corona of four equal pores, surrounded by a circle of twelve short teeth. Apex with four crossed, curved branches (like those of _Circospathis tetrodon_). Mouth cruciform, with four smooth teeth.

_Dimensions._--Diameter of the shell 0.24, length of the spines 0.12.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

3. _Circoporus characeus_, n. sp.

Shell spherical, covered with a delicate network of irregular polygonal plates. Six radial spines longer than the diameter of the shell, cylindrical, covered with numerous curved bristles, each with eight pores at the base surrounded by a circle of long bristles. Apex of each spine with a trident or fuscina, similar to that of the following species. Similar to an antheridium of Chara.

_Dimensions._--Diameter of the shell 0.32, length of the spines 0.4.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.

4. _Circoporus sexfuscinus_, n. sp. (Pl. 115, figs. 1-3).

Shell subregular, octahedral, with eight triangular, concave, somewhat unequal faces, which are covered with an extremely delicate network of small square dimples, and furrowed by radial crests arising from the bases of the spines (fig. 2). Six radial spines about as long as the diameter of the shell, four-sided, prismatic, with rounded edges; each in the basal half with a verticil of four crossed, curved bristles (fig. 1), sometimes with two verticils (fig. 2); on the distal apex inflated, armed with a trident or fuscina. Around the base of each spine four crossed elliptical pores. Mouth cruciform, with four small teeth (fig. 1).

_Dimensions._--Diameter of the shell 0.2 to 0.25, length of the spines 0.2 to 0.25.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

5. _Circoporus octahedrus_, n. sp. (Pl. 117, fig. 6).

Shell regularly octahedral, with eight plane, or slightly convex, congruent, triangular faces, which are covered with very small, regular, triangular plates (like those of _Polypetta tabulata_, Pl. 116, fig. 2). Six stout radial spines, about as long as the diameter of the shell, four-sided prismatic, {1696}covered with three or four verticils of four long curved bristles; at the distal apex inflated, with four crossed, divergent, stout, curved horns. Around the pyramidal base of each spine a corona of eight pores (two on each of the four faces). Mouth cruciform, with four triangular, convergent teeth.

_Dimensions._--Diameter of the shell 0.16, length of the spines 0.18.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.

Genus 712. _Circospathis_,[329] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Circoporida# with a subregular, spherical, or polyhedral shell, composed of fourteen triangular, nearly equal plates, with nine corners, from, which arise nine radial spines, symmetrically disposed.

The genus _Circospathis_ exhibits the remarkable and peculiar form of a "Tetradecahedron," or a subregular polyhedron with fourteen triangular faces, thirty edges, and nine corners, from which arise nine radial spines. These lie in three meridional planes, which are crossed at equal angles (three equidistant spines in each plane). The same interesting form occurs also in some Astrosphærida, which bear nine regularly disposed radial spines, as _Haliomma echinaster_. All four observed species of _Circospathis_ are South Atlantic.

1. _Circospathis furcata_, n. sp. (Pl. 115, figs. 4-6).

Shell polyhedral or nearly spherical, with nine prominent corners, from which arise nine radial spines, about as long as the diameter of the shell. The polygonal plates of the shell are separated by high crests, usually hexagonal or pentagonal, irregular, about twelve to fifteen on the half meridian. Radial spines cylindrical, straight, about as long as the diameter of the shell, with spirally turned edges, covered with numerous curved bristles, at the distal end forked; the two fork branches curved, one-third as long as the simple basal part. The inflated base of each spine is surrounded by a corona of nine to twelve ovate basal pores. Mouth pentagonal, with five thick, mammillate and spinulate, somewhat convergent teeth (fig. 5).

_Dimensions._--Diameter of the shell 0.6, length of the spines 0.5.

_Habitat._--South Atlantic (east of Buenos Ayres), Station 325, depth 2650 fathoms.

2. _Circospathis novena_, n. sp. (Pl. 117, figs. 3, 3_a_).

Shell polyhedral (tetradecahedral), with fourteen triangular, plane, or slightly convex faces, covered with small, irregular, polygonal (usually hexagonal) plates, and nine prominent corners, from which arise nine radial spines, shorter than the diameter of the shell. Each spine is surrounded at the broader base by a circle of twelve to sixteen pores and a corona of bristles, and bears at the {1697}inflated distal apex a trident or fuscina, similar to that of _Circoporus sexfuscinus_ (Pl. 115, fig. 2). Mouth with nine convergent, conical, denticulate teeth (fig. 3_a_).

_Dimensions._--Diameter of the shell 0.6, length of the spines 0.4.

_Habitat._--South Atlantic, Station 318 (east of Patagonia), depth 2040 fathoms.

3. _Circospathis tetradeca_, n. sp.

Shell spherical, covered with irregular, polygonal plates. Nine radial spines, cylindrical, as long as the radius of the shell, bristly, armed at the distal apex with a trident. (In one specimen six spines possessed three terminal branches, two spines two branches, and one spine four branches.) The broader base of each spine is surrounded by a corona of nine pores and a circle of curved bristles. Mouth with nine smooth conical teeth.

_Dimensions._--Diameter of the shell 0.55, length of the spines 0.3.

_Habitat._--South Atlantic, Station 332 (west of Tristan da Cunha), depth 2200 fathoms.

4. _Circospathis tetrodonta_, n. sp. (Pl. 115, fig. 10).

Shell subspherical or polyhedral, with fourteen triangular, convex faces, covered with irregular polygonal plates. Nine radial spines cylindrical, nearly smooth, about as long as the diameter of the shell; at the distal apex with four strong curved horns, like those of _Circoporus hexastylus_, Pl. 117, fig. 4. Each spine is surrounded at the base by a corona of nine irregular pores. Mouth with four large, prominent, conical teeth, which are spinulate, with vertical inner edge (fig. 10).

_Dimensions._--Diameter of the shell 0.5, length of the spines 0.45.

_Habitat._--South Atlantic, Station 323 (east of Buenos Ayres), depth 1900 fathoms.

Genus 713. _Circogonia_,[330] n. gen.

_Definition._--#Circoporida# with a regular icosahedral shell, composed of twenty congruent, triangular plates, with twelve corners, from which arise twelve radial spines.

The genus _Circogonia_ is remarkable for the regular icosahedral form of its shell, a geometrical fundamental form, which occurs very rarely in organised bodies (as in _Aulacantha icosahedra_, and in some Astrosphærida with twelve regularly disposed radial spines). The shell is composed of twenty triangular, equilateral and congruent plates, which are sometimes separated by prominent crests; their surface is panelled by smaller hexagonal or polygonal secondary plates. The thirty edges between the plates are sometimes thickened. From the twelve corners of the regular icosahedron (where every five triangular plates meet), twelve equal radial spines arise, each of which is surrounded at the base by a corona of nine to sixteen pores. Two species only of _Circogonia_ have been observed; the one has smooth spines, forked at the distal end, {1698}the other bears numerous curved bristles around each spine, and at the distal end a verticil of five curved branches. The mouth of the shell (placed in the centre of one of the triangular plates) is in both species armed with six teeth. Both species are found in the Tropical Atlantic.

1. _Circogonia icosahedra_, n. sp. (Pl. 117, figs. 1, 1_a_).

Shell regularly icosahedral, with twenty equal, triangular, nearly plane faces, which are separated by thirty prominent, crest-like edges, and covered by a delicate network of small, subregular, hexagonal plates. Twelve radial spines nearly conical, one and a half times as long as the radius of the shell, with five prominent edges. The campanulate base of each spine is covered with numerous long, curved bristles, surrounded by a circle of twelve to sixteen ovate, irregular pores, and separated from the slender distal part by a constriction. The distal apex of the spine is surrounded by a verticil of five conical, curved branches (corresponding to the five edges of the spines, and to the five faces, which meet in the corners where the spine arises). Mouth hexagonal, with six conical, spinulate teeth, convergent towards its centre (fig. 1_a_).

_Dimensions._--Diameter of the shell 0.75, length of the spines 0.5.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

2. _Circogonia dodecacantha_, n. sp. (Pl. 115, figs. 8, 9).

Shell subregularly icosahedral, with twenty equal, triangular, slightly convex faces, which are not separated by prominent crests, but covered with a network of irregular polygonal plates. Twelve radial spines, cylindrical, smooth, about as long as the diameter of the shell, forked at the distal end with two divergent, slightly curved branches (similar to _Circospathis furcata_, Pl. 115, figs. 4-6). The conical base of each spine is surrounded by a circle of nine to twelve irregular, ovate pores (fig. 9). Mouth circular, with a corona of six conical, smooth teeth which arise perpendicularly from the shell (in the upper part of fig. 8, at left).

_Dimensions._--Diameter of the shell 0.6, length of the spines 0.7.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

Genus 714. _Circorrhegma_,[331] n. gen.

_Definition._--#Circoporida# with a regular dodecahedral shell, composed of twelve congruent, pentagonal plates, with twenty corners, from which arise twenty radial spines.

The genus _Circorrhegma_ is remarkable for the geometrical regularity of its shell, which represents a pentagonal dodecahedron. The shell is therefore composed of twelve equal and regular pentagonal plates, and these are separated in the only known {1699}species by thirty prominent crest-like edges. From the corners of the dodecahedron, at which every three pentagons meet, arise twenty radial spines, opposite in pairs in ten equidistant axes.

1. _Circorrhegma dodecahedra_, n. sp. (Pl. 117, figs. 2, 2_a_).

Shell dodecahedral, with twelve equal and regular, plane, pentagonal plates, which are separated by thirty prominent crests, and bear a network of numerous polygonal (usually also pentagonal), smaller plates. Twenty radial spines about as long as the radius of the shell, three-sided prismatic, covered with numerous bristles; each surrounded at the thickened base by a circle of twelve to sixteen pores, and at the distal apex by a corona of five curved, terminal branches. Mouth pentagonal, with five conical, subvertical, spinulate teeth (fig. 2_a_).

_Dimensions._--Diameter of the shell 0.8, length of the spines 0.5.

_Habitat._--Indian Ocean, Madagascar (Rabbe).

Genus 715. _Circostephanus_,[332] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Circoporida# with a subregular, polyhedral or nearly spherical shell, composed of thirty to sixty or more triangular plates, with twenty-four to thirty-two or more corners, from which arise radial spines, symmetrically disposed.

The genus _Circostephanus_ comprises those Circoporida in which the porcellanous shell is an endospherical polyhedron, with numerous (thirty to sixty or more) triangular faces, and has a variable number of radial spines (twenty-four to forty or more), arising from its corners. The number of faces and corners seems to be variable in this genus, but may perhaps be typical in some species. _Circostephanus sexagenarius_ has the typical form of a "Sexagenal-Polyhedron," with sixty equal triangular faces and thirty-two corners, and may be derived from the "Pentagonal-Dodecahedron" (_Circorrhegma_) by dividing its twelve pentagonal faces each into five congruent triangles.

1. _Circostephanus coronarius_, n. sp. (Pl. 116, figs. 3, 3_a_, 3_b_).

Shell polyhedral, with thirty-two to forty triangular, concave faces of nearly equal size, which are separated by high prominent crests. From the elevated corners of the polyhedron arise twenty-four to thirty radial spines, which are three-sided prismatic or nearly cylindrical, about as long as the radius of the shell, and covered with long curved bristles. The distal end of each spine is surrounded by a verticil of five stout, curved branches, its pyramidal base by a corona of five (or {1700}sometimes six) ovate, basal pores (fig. 3_b_). Mouth armed with a corona of eight short, conical, vertical, spinulate teeth (fig. 3_a_).

_Dimensions._--Diameter of the shell 0.4 to 0.5, length of the spines 0.2 to 0.25.

_Habitat._--South-Eastern Pacific (off Valparaiso), Station 298, depth 2225 fathoms.

2. _Circostephanus sexagenarius_, n. sp.

Shell polyhedral, with sixty triangular, equilateral congruent faces which are nearly plane, and separated by high prominent crests. They are disposed in twelve pentagonal groups, each with five faces, so that they appear as if derived from a regular pentagonal dodecahedron, the twelve regular faces of which are each divided into five congruent triangles, meeting in its centre. From the elevated corners of the polyhedron arise thirty-two radial spines (twelve in the central points of the pentagons, twenty in the meeting corners of every three pentagons). The radial spines are nearly as long as the diameter of the shell, cylindrical, spinulate, and surrounded at the distal end by a verticil of five stout, curved branches, and at the pyramidal base by a corona of twelve to sixteen basal pores. Mouth armed with a corona of twelve conical, vertical, spinulate teeth.

_Dimensions._--Diameter of the shell 0.75, length of the spines 0.6.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.

3. _Circostephanus polygonarius_, n. sp.

Shell polyhedral, with sixty to eighty subregular, triangular, concave faces, which are separated by prominent crests. From the elevated corners of the polyhedron arise thirty to forty radial spines, which are longer than the diameter of the shell, densely covered with curved bristles and three-sided prismatic, with three spirally convoluted edges. Their distal end is surrounded by a verticil of eight or nine curved branches, and their pyramidal base by a corona of eight or nine basal pores. Mouth armed with a corona of ten conical, vertical, spinulate teeth.

_Dimensions._--Diameter of the shell 0.8, length of the spines 0.9.

_Habitat._--South Pacific, Station 288, depth 2600 fathoms.

Subfamily 2. HAECKELINIDA.

_Definition._--#Circoporida# with dimpled spherical shell, not composed of polygonal plates. The shell is covered with small roundish dimples, never polyhedral, and the radial spines are simple, not branched, and usually not regularly arranged.

Genus 716. _Haeckeliana_, John Murray, 1879, _in schedulis_, Chall. Coll.

_Definition._--#Circoporida# with spherical shell of a peculiar dimpled, porcellanous structure, and with a variable number of simple radial main-spines which are usually not regularly arranged.

{1701}The genus _Haeckeliana_ comprises the spherical Circoporida, with dimpled, porcellanous shell, which are widely distributed, but rather rare, in depths between 2000 and 3000 fathoms. All the known species (six in number) are very closely related, and though the extreme forms appear very different in size and structure, they are so connected by a continuous series of intermediate forms, that they may be regarded as varieties of a single species, first observed by Dr. John Murray, and called by him _Haeckeliana porcellana_. The number of radial spines may be from sixteen to fifty-five, and is usually between thirty and forty. Each is surrounded by a basal coronet of aspinal pores, usually five, more rarely four or six; the number, however, is not constant in any one species. Each coronet is armed with an outer ring of by-spines. The surface of the shell between the coronets is dimpled. The mouth (Pl. 114, fig. 3) is about as large as a corona, and also armed with a ring of by-spines. The structure of the thick porcellanous shell and the radial spines is different from the other Circoporida.

1. _Haeckeliana porcellana_, John Murray (Pl. 114, fig. 6).

_Haeckeliana porcellana_, John Murray, 1879, _in schedulis_, Chall. Coll.

Shell with forty to forty-five coronets, the majority of which have five pores (more rarely four or six). Coronets broader than their intervals, and twice as broad as the length of the by-spines. Dimples subcircular, of the same breadth as the pores. Main-spines about as long as the radius.

_Dimensions._--Diameter of the shell 0.37 to 0.42, of the coronets 0.06 to 0.07.

_Habitat._--South Pacific, Stations 289 to 293, depth 2025 to 2550 fathoms.

2. _Haeckeliana maxima_, n. sp. (Pl. 114, fig. 5).

Shell with fifty to fifty-five coronets, the majority of which have six pores (more rarely five or seven). Coronets broader than their intervals, and eight to ten times as broad as the length of the by-spines. Dimples irregularly polygonal, of about the same breadth as the pores. Radial main-spines about as long as the diameter of the shell.

_Dimensions._--Diameter of the shell 0.5 to 0.52, of the coronets 0.08 to 0.09.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.

3. _Haeckeliana lamarckiana_, n. sp. (Pl. 114, fig. 4).

Shell with thirty-five to forty coronets, the majority of which have five pores (more rarely six or four). Coronets broader than their intervals; each funnel-shaped pore on the inside with a circle of small conical thorns. By-spines rudimentary or wanting. Dimples irregularly polygonal, half as broad as the pores. Radial main-spines shorter than the radius.

_Dimensions._--Diameter of the shell 0.38 to 0.45, of the coronets 0.06 to 0.07.

_Habitat._--South Atlantic, Stations 318 to 333, depth 2000 to 2900 fathoms.

{1702}4. _Haeckeliana murrayana_, Haeckel.

_Challengeria_ sp., John Murray, 1876, Proc. Roy. Soc., vol. xxiv, pl. xxiv. fig. 6.

Shell with twenty to twenty-five coronets, the majority of which have five pores (more rarely four or six). Coronets of about the same breadth as their intervals, and twice as broad as the by-spines. Dimples subcircular, of about the same breadth as the pores. Radial main-spines about as long as the radius.

_Dimensions._--Diameter of the shell 0.35 to 0.4, of the coronets 0.06 to 0.07.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

5. _Haeckeliana goetheana_, n. sp. (Pl. 114, fig. 3).

Shell with sixteen to twenty coronets, the majority of which have four pores (more rarely five and very rarely six). Coronets smaller than their intervals. By-spines very short or rudimentary. Dimples subcircular, half as broad as the pores. Radial main-spines shorter than the radius.

_Dimensions._--Diameter of the shell 0.25 to 0.3, of the coronets 0.04 to 0.05.

_Habitat._--North Pacific (south of Japan), Station 231, depth 2250 fathoms.

6. _Haeckeliana darwiniana_, n. sp. (Pl. 114, figs. 1, 2).

Shell with twenty-six to thirty-two coronets, the majority of which have five pores (rarely four or six). Coronets smaller than their intervals and than the length of the by-spines. Dimples subcircular, half as broad as the pores, Radial main-spines longer than the radius.

_Dimensions._--Diameter of the shell 0.30 to 0.42, of the coronets 0.07 to 0.08.

_Habitat._--North Pacific (east of Japan), Stations 241 to 245, depth 2300 to 2900 fathoms.

Family LXXXII. #TUSCARORIDA#, n. fam. (Pl. 100).

_Definition._--PHÆODARIA with an ovate, spindle-shaped, or nearly spherical shell exhibiting a peculiar solid porcellanous structure; with a few radial pores around the base of the hollow tubules, which are symmetrically arranged around the main axis and the mouth. Surface of the shell smooth or spiny, not tabulate nor panelled. Central capsule excentric, placed in the aboral half of the shell-cavity.

The #Tuscarorida#, and the preceding closely allied family, the Circoporida, represent together a peculiar small group, which differs from the other PHÆODARIA in the singular porcellanous structure of the shell-wall, and may be called #Phæocalpia#; their hollow radial spines are distinguished by peculiar basal pores, forming a circle around their base. The shell of the Tuscarorida is monaxonian, ovate, spindle-shaped {1703}or nearly spherical, whilst in the Circoporida it is polyaxonian, spherical or polyhedral; the hollow radial spines are arranged in the former around the main axis, in the latter around the common central point. All #Phæocalpia# (the Tuscarorida as well as the Circoporida) are inhabitants of great depths, usually between 2000 and 3000 fathoms.

Though the number of Tuscarorida at present known is small (only three genera, with ten species), they represent a very distinct and remarkable family of PHÆODARIA, as well by their considerable size, as by the peculiar arrangement of the radial spines and the structure of the shell-wall, which in some species is more solid and thicker than in any other Radiolaria. The diameter of the shell is always more than 1 mm., usually between 1 and 2, and sometimes more than 3 mm.

The dry shell of the Tuscarorida is not hyaline and transparent as is usual in the other Radiolaria, but perfectly opaque, milk-white or yellowish-white. This opacity is caused by innumerable very fine pores, which everywhere pierce the thick, apparently solid, fundamental substance of the shell-wall. Besides those very small pores, it is also pierced by a certain number of larger pores, which are scattered at wide distances (Narr. Chall. Exp., vol. i. pl. A, fig. 15_b_). These larger pores or pore-channels have a diameter of about 0.01 mm., and pierce the shell-wall either in a perpendicular or in an oblique direction. Very numerous straight, simple, and thin needles, usually 0.1 to 0.2 mm. in length, similar to the thin tangential needles of the Aulacanthida, are everywhere scattered tangentially in the cement-like fundamental substance, which seems to be a peculiar carbonic silicate; their axis is parallel to the shell-surface.

The general form of the shell is somewhat different in the three genera of Tuscarorida; ovate or spherical in _Tuscarora_ and _Tuscarusa_, which bear no caudal axial spine (Pl. 100, figs. 1-7), or sometimes three-sided pyramidal (fig. 4); it is spindle-shaped in _Tuscaridium_, which bears on the aboral pore an axial caudal spine (Pl. 100, fig. 8). In every case the main axis of the shell, determining its monaxonian fundamental form, is indicated by the mouth, which is placed in the oral pole of the main axis and prolonged into a short tube or proboscis.

The hollow apophyses, arising from the shell of the Tuscarorida, are always cylindrical, long and thin tubules, the narrow cavity of which communicates directly with the large shell-cavity. In the axis of the tubules lies a thin axial chord or funicle, composed of a few (usually three or four) siliceous threads which arise from bridges between the basal pores of the apophyses, and are twisted together like the strands of a rope. The axial funicle is connected with the thin wall of the tubular apophyses by innumerable very thin radial beams, perpendicular to the axis (Pl. 100, fig. 3_a_, 5_b_). The surface of the apophyses is almost constantly covered with numerous small bristles or spines, which are usually curved and directed towards their distal ends.

_Tuscarora_ (Pl. 100, figs. 1-6) exhibits two different groups of apophyses, which may be distinguished according to their different position and direction as "circoral {1704}teeth" and "aboral feet"; the teeth immediately surround the opening of the mouth, whilst the feet are remote from it and usually placed in the aboral half of the body, more rarely in the equator or in the oral half. The general form and structure are the same in both groups of apophyses, but their position and direction is different; the circoral teeth are directed forwards, often parallel (at the base at least), while the aboral feet are either divergent and directed backwards, or they diverge forwards in the basal part, then form a large arch, and finally curve backwards.

The number of the aboral feet, and their position relative to the circoral teeth, are different but probably constant in each single species, and serve, in the first place, for the distinction of genera and species. _Tuscarora_ (in restricted sense) (Pl. 100, figs. 1-6), has constantly three feet (comparable to the three cortinar feet of the tripodal NASSELLARIA); _Tuscarusa_ (Pl. 100, fig. 7) has four feet, opposite in pairs and forming a regular cross; _Tuscaridium_, finally (Pl. 100, fig. 8), has only one foot, which is situated in the main axis, on its aboral pole, and may therefore be called a caudal spine.

The number of the circoral teeth varies from two to four, and is usually three. Originally these three teeth alternate regularly with the three aboral feet, so that the latter may be regarded as perradial, the former as interradial (Pl. 100, figs. 1-4). The proportion of the number of each group of apophyses in the different species is synoptically shown in the following table:--

a = Depth in Fathoms. b = Challenger Station. c = Length of the Shell. d = Breadth of the Shell. e = Number of Feet. f = Number of Pedal Pores. g = Number of Teeth. h = Number of Dental Pores. +------------------------------+------+-----+-----+-----+---+---+---+---+ | | a | b | c | d | e | f | g | h | +------------------------------+------+-----+-----+-----+---+---+---+---+ | 1. _Tuscarora bisternaria_, | 3000 | 264 | 2.0 | 1.5 | 3 | 8 | 3 | 8 | | 2. " _murrayi_, | 2000 | 295 | 2.5 | 1.5 | 3 | 3 | 3 | 3 | | 3. " _wyvillei_, | 2250 | 291 | 1.5 | 1.4 | 3 | 4 | 3 | 4 | | 4. " _tetrahedra_, | 2450 | 348 | 2.5 | 2.0 | 3 | 4 | 3 | 3 | | 5. " _tubulosa_, | 3000 | 249 | 1.4 | 1.2 | 3 | 4 | 2 | 3 | | 6. " _porcellana_, | 2650 | 325 | 1.5 | 1.3 | 3 | 4 | 2 | 4 | | 7. " _belknapii_, | 2025 | 293 | 2.5 | 1.5 | 3 | 3 | 4 | 2 | | 8. _Tuscarusa medusa_, | 3125 | 253 | 1.2 | 1.0 | 4 | 4 | 2 | 2 | | 9. _Tuscaridium cygneum_, | 3050 | 250 | 3.2 | 1.6 | 1 | 2 | 4 | 4 | |10. " _lithornithium_, | 3000 | 264 | 3.6 | 1.8 | 1 | 4 | 4 | 6 | +------------------------------+------+-----+-----+-----+---+---+---+---+

The base of the apophyses in all Tuscarorida is inflated, conical, and pierced by a small number of large ovate pores, the typical "basal pores," which occur also in the closely allied Circoporida. The number of these basal pores varies from two to eight, and is usually three or four; it never becomes in this family so great as in the Circoporida, where each circle of pores is often composed of sixteen to twenty-four or more basal pores. The number seems to be rather constant in each single species, as may be seen in the preceding Table. The pedal pores (on the base of the aboral feet) are usually larger than the dental pores (on the base of the circoral teeth). Their form is {1705}usually irregularly ovate or triangular; their outer aperture is armed with spines or bristles, which are commonly larger than in the other parts of the apophyses.

The mouth of the shell varies in form, according to the number and arrangement of the teeth on its corners. It is therefore a narrow transverse fissure, with two broad opposite lips and two corners, in the bidental forms (Pl. 100, figs. 5, 7), triangular in the tridental species (figs. 1-4), quadrangular or square in the quadridental species, _Tuscarora belknapii_ (Narr. Chall. Exp., _loc. cit._, pl. A, fig. 15). The singular genus _Tuscaridium_ (fig. 8) exhibits four teeth, which are nearly horizontally divergent in two pairs, a dorsal and a ventral pair (corresponding in position to the four feet of _Tuscarusa_, fig. 7); the mouth is here prolonged into a cylindrical, spinulate proboscis, which is curved towards the ventral face of the shell (fig. 8).

The _central capsule_ of the Tuscarorida is kidney-shaped or spheroidal, scarcely half as large as the dark olive-green phæodium, which surrounds its anterior (oral) face. Usually the capsule and the phæodium together fill up the aboral half of the shell-cavity, and are separated from its walls by the calymma. The latter is pierced by numerous branched and reticulately anastomosing pseudopodia, which arise from the matrix enveloping the capsule, and pass over into a thin layer of sarcode, adjacent to the inner surface of the shell. The astropyle or the main-opening of the central capsule exhibits the usual radiate operculum and tubular proboscis of the PHÆODARIA (Pl. 115, fig. 3), and is directed towards the mouth of the shell. The number of the parapylæ or accessory openings seems to be variable in this family, and to correspond to the number of radial feet which arise from the shell. Therefore _Tuscaridium_ possesses only one parapyle, which is diametrically opposite to the mouth, lies on the aboral pole of the capsule, and is directed towards the single caudal tube. _Tuscarora_ seems to have three parapylæ, corresponding to the three radial feet, and _Tuscarusa_ probably has four parapylæ, directed towards its four radial feet; in the latter genus, however, the capsule was not observed (the shell being empty); and in the other Tuscarorida this important and difficult anatomical question must be solved by further accurate examinations.

The nucleus is nearly half as large as the central capsule, ellipsoidal, and contains numerous nucleoli. In one specimen of _Tuscarora belknapii_ I observed two nuclei in the central capsule, and in another specimen of the same species John Murray observed two central capsules (figured by him in the Narr. Chall. Exp., vol i. pl. A, fig. 15).

_Synopsis of the Genera of Tuscarorida._

Three equidistant aboral radial feet, 717. _Tuscarora_. Four equidistant aboral radial feet, 718. _Tuscarusa_. One single aboral foot or terminal spine, 719. _Tuscaridium_.

{1706}Genus 717. _Tuscarora_,[333] John Murray, 1876, _in schedulis_, Chall. Coll.

_Definition._--#Tuscarorida# with three radial aboral feet, and a variable number of circoral teeth.

The genus _Tuscarora_ comprises seven of the ten observed species of Tuscarorida, all seven agreeing in the possession of three perradial feet, which alternate originally (in four species), with three interradial teeth surrounding the mouth. The latter is armed in two other species with two teeth, and in one species with four teeth (compare above, p. 1704). The three perradial feet have a similar position as in the tripodal NASSELLARIA, so that they may be distinguished as an odd caudal foot and two paired lateral feet.

Subgenus 1. _Tuscarantha_, Haeckel.

_Definition._--Shell with three perradial equidistant feet and three interradial equidistant circoral teeth, alternating regularly with the former.

1. _Tuscarora bisternaria_, John Murray (Pl. 100, figs. 1, 1_a_).

_Tuscarora bisternaria_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, figs. 16, 16_a._

Shell subspherical, with three lateral perradial feet in the equatorial zone, and three basal interradial teeth around the mouth, alternating regularly with the former. The three lateral feet arise either in the equator itself or a little above it, and are nearly horizontally expanded, descending a little towards the aboral pole. They are straight, cylindrical, twice to four times as long as the shell, geniculate at the inflated base, and covered with small thorns. A circle of six to eight basal pores in the base of each foot. The narrow mouth is triangular, surrounded by the thorny, inflated, subspherical bases of the three long, cylindrical, diverging, thorny teeth, which ascend obliquely and are longer than the shell; each tooth exhibits in the upper part of the inflated base a corona of eight to ten ovate holes.

_Dimensions._--Length of the shell 2.0, breadth 1.5.

_Habitat._--Central Pacific, Station 264, depth 3000 fathoms.

2. _Tuscarora murrayi_, n. sp. (Pl. 100, fig. 2). John Murray, 1876, L. N. 27, pl. 24, fig. 4.

Shell pear-shaped, with three circoral perradial feet in the upper third and three basal interradial teeth around the mouth. The three lateral feet are thin, cylindrical, arcuate, very bristly, arise immediately beyond the narrow tubular peristome, and ascend obliquely nearly to the height of the mouth; then they are curved downwards in a large arc, three to four times as long as {1707}the shell. The tubular peristome is about half as long as the shell, bottle-shaped, nearly three-sided prismatic, and bears three very long spinulate teeth, which in the lower half are parallel, in the upper slightly curved and diverging, at the base pear-shaped. Three ovate basal pores in the inflated base of each foot and each tooth.

_Dimensions._--Length of the shell 2.5, breadth 1.5.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.

3. _Tuscarora wyvillei_, n. sp. (Pl. 100, figs. 3, 3_a_-3_c_).

Shell subspherical, pellucid, thinner and more fragile than in the other species of the genus, with three aboral perradial feet in the lower third, and three interradial teeth around the wide mouth. The three feet are straight, conical, widely divergent, shorter than the shell, and arise from its lower third; on the inflated base of each four small ovate pores. The three teeth, alternating with them, are straight, cylindrical, arise from the margin of the mouth and diverge obliquely upwards. On the base of each foot four opposite cordate pores of very unequal size.

_Dimensions._--Length of the shell 1.5, breadth 1.4.

_Habitat._--South Pacific, Station 291, depth 2250 fathoms.

4. _Tuscarora tetrahedra_, John Murray (Pl. 100, figs. 4, 4_a_).

_Tuscarora tetrahedra_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 19.

Shell tetrahedral or three-sided pyramidal, with three perradial basal feet, and three alternate, interradial, circoral teeth. The three rounded edges of the pyramid are prolonged directly over the aboral base into the three short, divergent, conical, basal feet, which are smooth and scarcely one-fourth as long as the shell. The base of each foot is pierced by four small crossed pedal pores. The narrow mouth, on the apex of the pyramid, is surrounded by three short and broad, triangular, spinulate teeth, each of which bears three slender, triangular, dental pores.

_Dimensions._--Length of the shell 2.5, breadth 2.0.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

Subgenus 2. _Tuscaretta_, Haeckel.

_Definition._--Shell with three perradial equidistant feet, and with two circoral teeth, which are opposite in the radius of the odd dorsal foot; therefore a dorsal and a ventral tooth.

5. _Tuscarora tubulosa_, John Murray (Pl. 100, figs. 5, 5_a_, 5_b_).

_Tuscarora tubulosa_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 17.

Shell subspherical, with three lateral perradial feet on the upper half of the shell (above the equator), and two parallel vertical teeth on the mouth. The three feet arise between the upper and {1708}the middle third of the shell, diverge upwards, and are slightly arcuate, covered with numerous curved spines. Their base is pierced by four pedal pores. The peristome is a narrow sagittal fissure, placed in the radius of the odd or dorsal foot, and bears two opposite teeth on its two corners. The teeth are cylindrical, longer than the shell, covered with curved spines, and ascend in a parallel and vertical manner; each is perforated at the base by three large dental pores.

_Dimensions._--Length of the shell 1.4, breadth 1.2.

_Habitat._--North Pacific, Stations 244 to 250, depth 2050 to 3050 fathoms.

6. _Tuscarora porcellana_, John Murray (Pl. 100, figs. 6_a_, 6_b_).

_Tuscarora porcellana_, John Murray, 1819, _in litteris_, Narr. Chall. Exp., pl. A, fig. 18.

Shell pear-shaped, with three lateral perradial feet in the lower half of the shell, and two parallel vertical teeth on the mouth. The three lateral feet arise between the middle and the lower third of the shell, are straight, cylindrical, spinulate, about as long as the shell and diverge downwards; their base is pierced by four ovate pedal pores. The two parallel and vertical teeth are straight, shorter than half the shell, and opposite in the sagittal plane, on the two corners of the narrow mouth, in the radius of the dorsal odd foot. The base of each tooth exhibits four cordate dental pores.

_Dimensions._--Length of the shell 1.5, breadth 1.3.

_Habitat._--South Atlantic, Station 325, depth 2650 fathoms.

Subgenus 3. _Tuscarilla_, Haeckel.

_Definition._--Shell with three perradial equidistant feet, and with four crossed equidistant teeth around the mouth.

7. _Tuscarora belknapii_, John Murray.

_Tuscarora belknapii_, John Murray, 1879, _in litteris_, Narr. Chall. Exp., vol. i. p. 226, pl. A, figs. 15, 15_a_-15_d._

Shell pear-shaped, with three lateral perradial feet in the upper third, and four crossed teeth around the mouth. The three arcuate feet are thin, cylindrical, covered with small curved thorns, and arise at the base of the peristome, between the upper and middle third of the shell; they ascend diverging to the height of the mouth, and are then curved downwards in a large arc, twice to three times as long as the shell. The base of each foot is dilated and pierced by three pedal pores. The four thin and long teeth of the peristome are similar to the feet, ascend in a slightly diverging manner, and are so placed that two opposite lie in the sagittal plane (or in the radius of the dorsal odd foot), whilst the two others are opposite in the frontal plane (perpendicular to the former). The base of each tooth exhibits two large ovate dental pores.

_Dimensions._--Length of the shell 2.5, breadth 1.5.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

{1709}Genus 718. _Tuscarusa_,[334] n. gen.

_Definition._--#Tuscarorida# with four radial aboral feet and a variable number of circoral teeth.

The genus _Tuscarusa_ differs from the preceding closely allied _Tuscarora_ in the possession of four radial feet instead of three. The mouth of the single observed species is a narrow sagittal fissure, and armed with two opposite teeth (a dorsal and a ventral, as in the subgenus _Tuscaretta_). The four lateral feet form a cross, and lie opposite in pairs, in two diagonals of the square, which is bisected by the sagittal mouth.

1. _Tuscarusa medusa_, n. sp. (Pl. 100, figs. 7, 7_a_).

Shell ovate, with four crossed lateral feet in the upper third, and with two opposite teeth around the mouth. The four feet are opposite in pairs in two diameters of the shell, perpendicular one to another, and arise between the upper and middle third of the shell; they are thin, cylindrical, spinulate, arcuate, and ascend to the height of the mouth diverging upwards; then they are curved downwards in a large arc. They lie in the diagonals of the square, which is halved by the narrow and long fissure of the mouth. This lies in the original sagittal plane, and from its two corners arise the two opposite teeth (a dorsal and a ventral), diverging upwards, cylindrical and slightly curved. The base of each foot is pierced by four pedal pores, of each tooth by two dental pores.

_Dimensions._--Length of the shell 1.2, breadth 1.0.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.

Genus 719. _Tuscaridium_,[335] n. gen.

_Definition._--#Tuscarorida# without radial aboral feet, but with a terminal axial caudal foot, and a variable number of circoral teeth.

The genus _Tuscaridium_, comprising two closely allied species, differs from the two preceding genera of Tuscarorida in the absence of lateral radial feet, which are represented by a single large caudal spine placed in the main axis of the shell, at its aboral pole. The shell is therefore spindle-shaped, and not ovate or subspherical, as in the two other genera. It reaches in the two observed species a length of more than 3 mm.

1. _Tuscaridium cygneum_, Haeckel.

_Tuscarora cygnea_, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 20.

Shell spindle-shaped, twice as long as broad (in the transverse section circular), equally tapering towards both poles of the main axis. The aboral pole bears a thin, cylindrical, straight, caudal {1710}spine, placed in the prolongation of the main axis, and about half as long as the shell. Its base is pierced by two large opposite pedal pores. The anterior or oral pole bears a cylindrical peristome, similar to a bird's head, and curved towards the ventral face; on both sides of its neck (at right and left) a series of three or four irregular, ovate, buccal holes. The neck bears four cylindrical, spinulate, radial tubes (two on each side), crossed nearly horizontally, and placed in two diagonal planes perpendicular one to another; these planes correspond to those in which the four feet of _Tuscarusa medusa_ lie. The base of each tube is pierced by four dental pores.

_Dimensions._--Length of the shell 3.2, breadth 1.6.

_Habitat._--North Pacific, Station 250, depth 3050 fathoms.

2. _Tuscaridium lithornithium_, n. sp. (Pl. 100, figs. 8, 8_a_, 8_b_).

Shell spindle-shaped, twice as long as broad, very similar to the preceding closely allied species. It differs from the latter in the following characters:--The curved proboscis of the peristome is broader and more spiny. The four radial tubes of the mouth and the terminal caudal spine are very spiny (in the preceding species nearly smooth). The number of buccal holes (six to eight on each side of the mouth) is twice as great as in the former. Each circoral tube is pierced at the base by six or eight (in the former by four pores), and the base of the caudal spine exhibits a cross of four pores (in _Tuscaridium cygneum_ only two pores).

_Dimensions._--Length of the shell 3.6, breadth 1.8.

_Habitat._--North Pacific, Station 264, depth 3000 fathoms.

----

Order IV. PHÆOCONCHIA, Haeckel, 1879.

_Definition._--PHÆODARIA with a bivalved lattice-shell, composed of two free opposite valves (a dorsal and a ventral), between which the central capsule is enclosed.

Family LXXXIII. #CONCHARIDA#, Haeckel, 1879 (Pls. 123-125).

_Concharida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--PHÆODARIA with a bivalved lattice-shell, which is spherical or lenticular, and composed of two equal or unequal boat-shaped valves, a dorsal and a ventral. The valves bear neither an apical latticed cupola or galea, nor hollow radial tubes. The central capsule is placed in the aboral half of the shell-cavity, and so enclosed between both valves, that its three openings lie in the open frontal fissure between them (the astropyle on the oral pole of the main axis, the two parapylæ on both sides of its aboral pole, at right and left).

{1711}The family #Concharida# and the two following closely allied families, the Coelodendrida and Coelographida, compose together the most remarkable and interesting suborder of #Phæoconchia# (or "PHÆODARIA bivalva"), differing from all the other Radiolaria in the possession of a bivalved lattice-shell, composed of two separate valves, like the shell of a Brachiopod. The central capsule is so enclosed between the two fenestrated valves that its three openings lie in the horizontal open (frontal) fissure between them, the astropyle or main-opening on the oral pole of the main axis; the two secondary openings or parapylæ on the two sides of its aboral pole, at right and left. The plane in which the three openings lie is therefore the frontal plane, dividing the entire body into a dorsal and a ventral half. The two valves, accordingly, must be considered as dorsal and ventral valves (as in the Brachiopoda), and the symmetrical halves of each valve as right and left. These halves may be always easily distinguished, since the oral pole of each valve is constantly different from the aboral pole. The voluminous phæodium always lies in the oral half, and the central capsule in the aboral half of the shell-cavity, whilst the calymma encloses the whole shell.

The Concharida differ from the other two families of bivalved PHÆODARIA in the absence of the apical galeas, and the branched hollow tubes arising from them. Each of these two cupolas, which are at the opposite poles of the sagittal axis (one cupola on the apex of each valve), is in the Coelographida connected by a simple or double frenulum with a peculiar rhinocanna, or an open nasal tube directed towards the mouth; whilst the cupolas of the Coelodendrida possess neither a rhinocanna nor a frenulum. The three families of #Phæoconchia# may therefore represent a phylogenetical series, the common root of which are the Concharida. From these are developed the Coelodendrida by development of an apical cupola or galea on each valve, and of hollow radial tubes arising from it; whilst the Coelographida are developed from the latter by production of a rhinocanna on the base of each cupola, and of one or two frenula connecting the former with the latter.

All the Concharida described in the following pages (seven genera and thirty species), are perfectly new to science, and not a single form of this interesting family was known before the explorations of the Challenger. Some species (mainly of the genera _Conchidium_ and _Conchopsis_) are by no means rare, and are found in great numbers at some stations of the tropical seas (in the Pacific as well as in the Atlantic). All described species are closely allied, agree in the majority of characters, and are easy to distinguish from all the other Radiolaria. Some few forms of Concharida, however, form a direct passage to the Coelodendrida.

Regarding the probable origin of the Concharida (and therefore also of all other #Phæoconchia# derived from the latter), two different hypotheses are possible. They have either been derived directly from the skeletonless _Phæodina_, by development of a bivalved lattice-shell; or they may be derived from PHÆODARIA with a simple {1712}spherical lattice-shell (Castanellida), by the halving of this latter, or its splitting into two hemispherical valves; the former hypothesis is more probable than the latter.

The two valves of the lattice-shell (Pls. 123-126) must in the Concharida (as in all other #Phæoconchia#) be distinguished as dorsal and ventral, and may therefore be compared with the two valves of the Brachiopoda, not with those of the Lamellibranchia. This important morphological distinction is expressed by the constant position of the central capsule within the shell-cavity. The capsule always exhibits the character of the "TRIPYLEA" and has three tubular openings, placed in the frontal or lateral plane of the unicellular body. In the same plane lies the open frontal fissure between the two valves, and the three openings are so disposed in it that the large anterior main-opening (or the astropyle) is placed on the oral pole of the main axis, whilst the two accessory small lateral openings or parapylæ are placed on both sides of the aboral pole, at the right and left. Therefore in a dorsal or ventral view all three openings are visible (Pl. 123, figs. 1, 8_a_); in the usual lateral view, however, from the right or left side, only two openings are visible, the astropyle on the anterior, and one parapyle (right or left) near the posterior pole of the main axis (Pl. 123, figs. 8, 9; Pl. 124, figs. 6, 10). The posterior view (from the aboral pole) shows the two parapylæ, at right and left; in the anterior view (from the oral pole) the astropyle may be visible, but usually it is completely hidden in the dark voluminous phæodium. This latter envelops sometimes nearly the whole capsule as an opaque conglomeration of green or brown phæodella (Pl. 123, figs. 8, 9); but usually the phæodium fills up the anterior (oral) half of the shell-cavity, whilst the capsule occupies the posterior (aboral) half (Pl. 124, figs. 6, 10).

The dorsal shell-valve is in almost all PHÆODARIA smaller or somewhat different in shape from the ventral valve, and this difference is often very striking (Pl. 124, figs. 3-16); but in a few species both valves are so similar, that I could not discover any certain difference. This equality of the two valves occurs mainly in those Concharida which pass over into the Coelodendrida; in these latter as well as in the Coelographida, both valves are usually equal in size and form. Whilst the main axis (or the longitudinal axis of the body) in the two latter families of #Phæoconchia# seems to be normally vertical (in the living and freely floating body), in the living Concharida it is probably horizontal, so that the larger and heavier ventral valve lies below the smaller and lighter dorsal valve.

The geometrical fundamental form of the body is therefore in the Concharida dipleural or bilaterally symmetrical, and we distinguish in it the same three dimensive axes, as in all other dipleural forms. On the anterior or oral pole of the main axis (or longitudinal axis) lies the mouth of the shell, and behind it the phæodium; on the opposite posterior or aboral pole lies the hinge of the shell (comparable to the shell-hinge of the Brachiopoda) and in front of it the central capsule. The sagittal (or {1713}dorso-ventral) axis, determining the height of the shell, has on its dorsal (or upper) pole the apex or highest point of the dorsal valve, on its ventral (or lower) pole the apex or lowest point of the ventral valve. The two poles of the frontal (lateral or transverse) axis are equal and are determined by the two parapylæ of the capsule, and the corresponding points of the shell-fissure between both valves. Usually the main-axis is the longest, the frontal axis the shortest, and between both the sagittal axis.

In regard to the three dimensive planes which are determined by these three axes, perpendicular to one another, they are rarely of nearly equal size (as in some subspherical species), usually the sagittal plane (separating the right and left halves of the body) is the largest; the cinctural or equatorial plane (separating oral and aboral halves) is the smallest, and the frontal or lateral plane (separating dorsal and ventral halves) is intermediate in size. The relation of the three perimeters of these three planes corresponds to that proportion; the sagittal perimeter (in which the keel of the compressed valves lies) is the largest; the cinctural or equatorial perimeter (separating the anterior phæodium and the posterior central capsule) is the smallest, and the frontal or lateral perimeter (in which the fissure between the valves lies) is intermediate in size.

The general form of the single valves is very varied in the different species, in the majority boat-shaped or hat-shaped, more or less laterally compressed, in a few forms hemispherical. In _Conchopsis_ (Pl. 125) and _Conchoceras_ (Pl. 124, figs. 15, 16) the lateral parts of the valves (right and left) are vaulted, whilst their median parts are so strongly compressed that they form a sharp sagittal keel, and then the shell in the dorsal or ventral view appears spindle-shaped (Pl. 123, fig. 8_a_; Pl. 125, fig. 8). Often the frontal margins of the valves are somewhat constricted (Pl. 124, fig. 7).

The junction between the two valves of the shell is always loose, but not so loose as in the two following families. In the Coelodendrida and Coelographida the two valves are either perfectly free and separated by a frontal zone of jelly, or in very loose contact on the frontal margins. In the Concharida, however, the margins of both valves seem to be usually in contact, and their connection is effected in a double way. In the subfamily Conchasmida (comprising the genera _Concharium_ and _Conchasma_, Pl. 123, figs. 1-6) the lateral margins of both valves are smooth, not dentated, and fit one into another like the two parts of a box, or like the two valves of a Diatom (_Navicula_). In the second subfamily, however, Conchopsida (comprising the five other genera, Pls. 124, 125), the lateral margins of the valves are dentate, usually provided with a series of numerous strong conical teeth, and the teeth of both valves so catch into one another, that their union is rather firm (like the margin of the shells of _Tridacna_, _Pecten_, and other Lamellibranchiata). Besides, a more solid junction is often effected on the posterior or aboral part of the margins, which we shall call the hinge. Here often peculiar strong teeth catch one into another, and in the majority of species {1714}two aboral spines are developed, the caudal horns (a dorsal and a ventral); these are very large in _Conchoceras_ (Pl. 124, figs. 15, 16). But a peculiar and most interesting kind of junction is effected in some Concharida by a true ligament between the valves (Pl. 123, figs. 8, 9; Pl. 125, fig. 2). This ligament is always placed on the aboral hinge, is of dark brown colour, and is not dissolved by mineral acids unless long applied. It may preserve the connection of the posterior parts of both valves, when their anterior parts are removed one from another, just as in the Brachiopoda. I observed this interesting ligament mainly in the genus _Conchopsis_, but not in all species, and it is not yet certain whether it is a constant organ in these and some other Concharida.

In the majority of Concharida the lateral margins of the two valves project slightly inwards into the cavity, and in some species of _Conchopsis_ these inner borders are so broadened that they form a broad, horizontal, fenestrated inner shelf, comparable to the deck of a boat or to the velum of the Hydromedusæ or Craspedotæ (Pl. 125, fig. 9). In this case the velum surrounds the ovate aperture through which the two lobes of the central capsule (dorsal and ventral) enter into the cavity of both valves.

The mouth of the shell lies on the oral pole of the main axis, and is therefore opposed to the aboral hinge. The two valves are here usually more or less emarginate, so as to form a transverse mouth with an upper and a lower lip (Pl. 124, figs. 6, 7, 11). The form of these two lips is often very different and characteristic of particular species (Pl. 124, figs. 3, 15, 16). The mouth remains in many species constantly open, even when the frontal fissure is closed (figs. 7, 16). Since the centre of the shell mouth lies in the prolongation of the proboscis arising from the operculum of the central capsule, probably the main stream of sarcode, issuing from the latter, becomes protruded by the former.

Apophyses of the shell (besides the teeth of the margins) are completely wanting in three genera, _Concharium_, _Conchellium_, and _Conchopsis_ (Pl. 123, figs. 1-4, 7; Pl. 125). The four other genera possess free apophyses or spines, which we call horns. They are probably important as the beginnings of those large hollow tubes which are characteristic of the two following families, Coelodendrida and Coelographida. We distinguish two different forms of horns, apical horns on the poles of the sagittal axis, and caudal horns on the aboral pole of the main axis; the former probably correspond to the sagittal tubes and the latter to the caudal tubes of the two following families. Apical horns are found in a single genus only, _Conchonia_ (Pl. 124, figs. 10-14). Here either on one pole or on poles of the sagittal axis a horn is developed, usually curved backwards. Sometimes the base of this conical horn is inflated and fenestrated, and may represent the beginning of the formation of the galea or apical cupola of the Coelodendrida.

The two caudal horns are opposite on the aboral hinge of the shell, one arising from the posterior end of each valve. Usually they are short and thick, pyramidal, the {1715}ventral horn larger than the dorsal (Pl. 124, figs. 3, 6). Rarely the two caudal horns are fenestrated at the base and reach a considerable size, as in _Conchoceras_ (Pl. 124, figs. 15, 16).

The walls of the bivalved shell usually exhibit in the Concharida a rather solid shape and regular structure, with an elegant network of regularly arranged pores. But in some species the walls of the shell become very thin and fragile, and assume the same shape (with very irregular network), as in the Coelodendrida and Coelographida. The pores are usually small and numerous, circular, often hexagonally framed (Pl. 125, figs. 4-6). They pierce the thick shell-wall either in a radial or in an oblique direction. Sometimes each pore is armed with six radial teeth (Pl. 123, fig. 7_a_). At other times each pore represents an oblique ampullaceous canal, dilated in its middle part, with two narrow openings (Pl. 125, figs. 5_a_, _b_, _c_, 6). The pores are so arranged in the majority of species that they form regular curved series, which are separated by prominent crests, and converge towards the poles of the main axis. Usually the marginal pores (along the frontal margin of the valves) are much smaller (compare Pls. 123-125).

The _central capsule_ of the Concharida, very well preserved in numerous specimens of the Challenger collection, constantly possesses the same situation and structure. It is always enclosed in the aboral or posterior half of the shell-cavity, whilst the oral or anterior half is filled up by the phæodium. The free spaces between both and between the inner surface of the shell are completely filled up by the jelly of the calymma, which also covers the whole shell as a thin outer jelly-envelope. The form of the central capsule is sometimes nearly spherical, usually somewhat compressed in the direction of the main axis, and sometimes also in the direction of the frontal axis (Pl. 123, figs. 1-9). In some species it becomes bilobed, with an upper dorsal and a lower ventral lobe, and in some others it becomes triangular (Pl. 125, fig. 7). Its two membranes (inner and outer) are often separated by a broad colourless interval, containing a clear fluid or jelly (Pl. 123, figs. 8, 9). The nucleus is usually about half as large as the central capsule and ellipsoidal, its longer axis lying in the sagittal diameter of the body. Several specimens (of different genera) contained two separate nuclei, one placed in the dorsal, the other in the ventral half of the capsule (Pl. 124, fig. 6). This duplication of the nucleus is probably the preparation for the division of the capsule. The division will be probably effected in the frontal plane, so that each half of the bisected capsule gets one nucleus and one valve, and the other valve becomes newly formed (in a way similar to that in the bivalved Diatomaceæ). The astropyle, or the main-opening of the capsule, is closed by a radiate operculum, from which arises a tubular proboscis; this lies in the main axis of the body, is directed towards the anterior mouth of the shell, and surrounded by the phæodium. The two shorter tubes of the paired parapylæ, or the accessory lateral openings, lie on the posterior or caudal side of {1716}the capsule, at right and left, and are directed half backwards, half outwards (towards the frontal fissure between the valves, Pl. 123, figs. 1, 8_a_).

The phæodium exhibits in all Concharida the same characteristic shape, and represents a dark conglomeration of phæodellæ, filling up the anterior or oral half of the shell-cavity. Usually it is bilobed, divided into a dorsal and a ventral lobe or wing, which fills up the corresponding valve of the shell (Pl. 123, figs. 8, 9). The phæodium is commonly more voluminous than the capsule, and surrounds its anterior half, more rarely it encloses nearly the entire capsule (Pl. 124, figs. 6, 10). Its colour is usually olive, sometimes more greenish, at other times more brownish, in some species nearly black. The phæodellæ, or the roundish granules which compose the phæodium, exhibit the same shape as in all other PHÆODARIA (compare above, p. 1535). Sometimes peculiar rather oblong nucleated cells are scattered in great numbers between the phæodellæ, probably parasites or symbiontes (Pl. 123, figs. 7-9, 9_a_).

_Synopsis of the Genera of Concharida._

------------------------------------------------------------------------- I. Subfamily Conchasmida. Lateral edges of the two valves smooth, without teeth. ------------------------------------------------------------------------- { Aboral hinge without Valves without sagittal { horns, 720. _Concharium_. keel, nearly hemispherical { or slightly compressed. { Aboral hinge with two { horns (one on each { valve), 721. _Conchasma_. ------------------------------------------------------------------------- II. Subfamily Conchopsida. Lateral edges of the two valves dentate, with a series of prominent teeth on both sides. The teeth of both valves catch one into another. ------------------------------------------------------------------------- { Aboral hinge without { horns, 722. _Conchellium_. { Valves without sagittal { Aboral hinge with two keel, nearly hemispherical { horns. No apical horn, 723. _Conchidium_. or slightly compressed. { { Aboral hinge with two { horns. Apex also with { a horn, 724. _Conchonia_.

{ Aboral hinge without Valves with a sharp { horns, 725. _Conchopsis_. sagittal keel, strongly { compressed on both sides, { Aboral hinge with two boat-shaped. { horns (one on each { valve). 726. _Conchoceras_.

Subfamily 1. CONCHASMIDA, Haeckel.

_Definition._--#Concharida# with the lateral margins of the two valves smooth, without interlocking teeth.

Genus 720. _Concharium_,[336] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Concharida# with the lateral margins of the valves smooth, without sagittal keel and without horns on the hinge.

{1717}The genus _Concharium_ is the simplest and the most primitive form of all Concharida; it may be regarded as the common ancestral form of the whole family. The entire shell is usually almost spherical, without horns or teeth, and may be regarded as a _Castanella_ which is bisected or broken into two equal hemispherical halves. The lateral margins of the two hemispherical valves are smooth, without teeth, and catch one into the other like the two valves of a Diatom, or the two halves of a bivalved box. _Concharium_ agrees in this simple shape of the frontal margins with the following genus _Conchasma_, and represents with it the small subfamily Conchasmida.

1. _Concharium bivalvum_, n. sp. (Pl. 123, figs. 2, 2_a_).

Shell spherical, smooth. Diameter in all directions nearly the same. Borders of the two hemispherical valves circular, smooth, about twice as broad as the pores. In the half frontal perimeter of the shell (along the right and the left border of each valve) twenty-two to twenty-four pores, in the half sagittal perimeter (in the middle line of each valve) eighteen to twenty-two pores, in the half equator (in the cinctural perimeter of each valve) twenty to twenty-two pores. All pores circular, of the same size, twice as broad as their bars.

_Dimensions._--Length of the shell (longitudinal diameter) 0.35, height (sagittal diameter) 0.34, breadth (lateral diameter) 0.33.

_Habitat._--North Atlantic, west of Madeira, Station 354, depth 1675 fathoms.

2. _Concharium nucula_, n. sp. (Pl. 123, fig. 3).

Shell pear-shaped, with costate surface. Oral face somewhat truncated, broader than the aboral face. Its longitudinal diameter about one-fifth longer than the two other diameters. Borders of the two valves ovate, smooth, about as broad as the pores. In the half frontal perimeter of the shell twenty-two to twenty-four pores, in the half sagittal perimeter eighteen to twenty, in the half equator sixteen to eighteen. Pores irregularly roundish, three to four times as broad as the bars. The pores are so disposed in meridional rows that the crests between the rows converge towards the two poles of the sagittal axis.

_Dimensions._--Length of the shell 0.2, height 0.18, breadth 0.16.

_Habitat._--South Atlantic (west of Tristan da Cunha), Station 332, depth 2200 fathoms.

3. _Concharium diatomeum_, n. sp. (Pl. 123, fig. 1).

Shell nearly spherical, slightly lenticular, somewhat compressed in dorso-ventral direction; the sagittal diameter therefore somewhat shorter than the two others. Borders of the two hemispherical valves nearly circular, quite smooth, about as broad as the length of the largest pores. In the half frontal perimeter of the shell forty-four to fifty pores; in the half sagittal perimeter twenty to twenty-four; in the half equator thirty to thirty-three. Pores different in form and size; the {1718}marginal pores small, nearly circular; the dorsal and ventral pores oblongish-hexagonal, twice as long as broad, about four to six times as long as the bars, regularly arranged in transverse rows.

_Dimensions._--Length of the shell 0.22, height 0.21, breadth 0.2.

_Habitat._--Tropical Atlantic, near Sierra Leone, Station 348, depth 2450 fathoms.

4. _Concharium bacillarium_, n. sp. (Pl. 123, fig. 4).

Shell walnut-shaped, with panelled surface; oral and aboral face of the same form. Its longitudinal diameter about one-fifth longer than the two other diameters. Borders of the two cup-shaped valves elliptical, smooth, with a prominent edge, about as broad as the larger pores. In the half frontal perimeter of the shell fifty to fifty-five pores, in the half sagittal perimeter thirty-six to forty, in the half equator also thirty to forty. Pores hexagonally framed. The pores are tapering in size from the sagittal plane towards the valve-margins, and so regularly arranged in meridional rows that the crests between the latter converge towards both poles of the longitudinal axis.

_Dimensions._--Length of the shell 0.2, height 0.15, breadth 0.15.

_Habitat._--Tropical Atlantic, off St. Helena, Station 340, depth 1500 fathoms.

5. _Concharium fragilissimum_, n. sp.

Shell subspherical, very thin-walled and fragile. Diameter in all directions nearly the same. Oral and aboral face scarcely different. Margins of the hemispherical valves extremely thin and hyaline. Pores irregularly roundish, of very different sizes and unequal forms. The fragile shell of this species differs in general shape from that of all other Concharida, and is like that of the Coelodendrida (Pl. 121, fig. 3), but exhibits neither an apical cupola or galea, nor radial tubes arising from it. It may be perhaps a young specimen of _Coelodendrum_.

_Dimensions._--Diameter of the shell 0.22, of the pores 0.002 to 0.02.

_Habitat._--Mediterranean, Portofino (Haeckel), surface.

Genus 721. _Conchasma_,[337] n. gen.

_Definition._--#Concharida# with the lateral margins of the valves smooth, without sagittal keel, but with two caudal horns on the hinge (a dorsal and a ventral).

The genus _Conchasma_ is closely allied to the preceding _Concharium_, and has the same hemispherical valves with smooth margins, without teeth; but it differs from the latter in the development of two caudal horns or posterior spines on the aboral hinge, one horn on the aboral end of each valve. The three species of this genus were all found in great depths of the Antarctic Ocean, in Diatom ooze, between 1260 and 1975 fathoms, at Stations 152 to 157.

{1719}1. _Conchasma radiolites_, n. sp. (Pl. 123, fig. 5).

Shell nearly spherical, somewhat compressed on both sides; the dorsal valve smaller, flatter and shorter than the ventral valve. In the half sagittal perimeter of the shell twenty to twenty-two pores, in the half frontal perimeter twelve to fourteen, in the half equator eighteen to twenty. All pores nearly of the same size, circular, hexagonally framed, scarcely as broad as the bars. The two horns of the hinge are four-sided pyramidal, of different sizes; the ventral horn (of the larger valve) two to three times as long as the dorsal horn (of the smaller valve); the latter twice as long as a pore.

_Dimensions._--Length of the shell 0.16, height 0.15, breadth 0.14.

_Habitat._--Antarctic Ocean, Station 154, depth 1800 fathoms.

2. _Conchasma sphærulites_, n. sp. (Pl. 123, fig. 6).

Shell nearly spherical, somewhat compressed on both sides, the frontal diameter therefore somewhat shorter than the two others. Both valves nearly of the same size, hemispherical, their borders smooth, twice as broad as the largest pores. In the half sagittal perimeter of the shell twenty-eight to thirty pores, in the half frontal perimeter twenty to twenty-two, in the half equator twenty-four to twenty-six. Size of the pores increasing from the borders towards the top of the valves. One series of very small pores along the frontal free margin of each valve. Pores roundish-polygonal, three to four times as broad as the bars. The two horns of the hinge are of equal size, four-sided pyramidal, and twice as long as the larger pores.

_Dimensions._--Length of the shell 0.18, height 0.18, breadth 0.16.

_Habitat._--Antarctic Ocean, Station 152, depth 1260 fathoms.

3. _Conchasma hippurites_, n. sp.

Shell nearly spherical, scarcely compressed. The frontal diameter equal to the two others. Both valves equal. In the half sagittal perimeter of the shell thirty-two to thirty-four pores, in the half frontal perimeter twenty-four to twenty-six, in the half equator twenty-six to twenty-eight. All pores of nearly equal size, circular, polygonally framed, twice as broad as the bars. The two horns of the hinge are large, three-sided pyramidal, the ventral horn twice as long as the dorsal, and four to six times as long as one pore.

_Dimensions._--Length of the shell 0.22, height 0.21, breadth 0.2.

_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.

Subfamily 2. CONCHOPSIDA, Haeckel.

_Definition._--#Concharida# with the lateral margins of the two valves dentate, the teeth of both catch one into another.

{1720}Genus 722. _Conchellium_,[338] n. gen.

_Definition._--#Concharida# with the lateral margins of the valves dentate, without sagittal keel and without horns on the hinge.

The genus _Conchellium_ and the four following genera represent together the subfamily Conchopsida, differing from the Conchasmida in the dentate lateral margins of the two valves. These are armed with a series of strong, conical teeth, and catch one into another just as the two valves of many Lamellibranchiata and Brachiopoda do (Pl. 124, figs. 1-16). _Conchellium_ is the simplest form among the Conchopsida, since the valves are hemispherical, and possess neither a sagittal keel nor projecting horns.

1. _Conchellium tridacna_, n. sp. (Pl. 123, figs. 7, 7_a_).

Shell nearly spherical, finely tuberculated, the sagittal diameter somewhat longer than the two others. Borders of the two hemispherical valves smooth in 0.2 of the oral, and 0.1 at the aboral part, dentated in the remaining 0.7 part; on one side of each valve fourteen to sixteen very strong and long teeth, all nearly of the same size, about one-fourth as long as the shell-radius. In the half frontal perimeter of the shell (on one border of each valve) twenty-five to thirty pores, in the half sagittal perimeter thirty-five to forty, in the equator twenty-five to thirty. Pores circular, hexagonally framed, of equal size (except some smaller rows along the fissure), twice as broad as the bars. On the conical inside of each funnel-like pore six small spinules, between every three neighbouring pores a triangular facette (fig. 7_a_).

_Dimensions._--Length of the shell 0.34 to 0.38, height 0.38 to 0.42, breadth 0.32 to 0.36.

_Habitat._--North Pacific, Stations 250 to 253, depth 2740 to 3125 fathoms.

2. _Conchellium hippopus_, n. sp.

Shell nearly spherical, in the lateral perimeter (along the girdle-fissure) somewhat constricted. Borders of the two hemispherical valves semicircular, smooth in 0.3 of the oral, and 0.2 of the aboral part, dentated only in the remaining 0.5 middle part; on one side of each valve seven to eight very strong and long teeth, increasing in size towards the mouth, the longest (foremost) teeth nearly one-third as long as the shell-radius. In the half frontal perimeter of the shell (along one border of each valve) twenty-four to twenty-eight pores, in the half sagittal perimeter thirty-two to thirty-six, in the half equator twelve to fourteen. Pores circular, twice to three times as broad as the bars, smaller along the fissure.

_Dimensions._--Length of the shell 0.06, height 0.065, breadth 0.055.

_Habitat._--Central area of the Tropical Pacific, Station 274, depth 2750 fathoms.

{1721}Genus 723. _Conchidium_,[339] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Concharida# with the lateral margins of the valves dentate, without sagittal keel and apical horns, but with two caudal horns on the hinge (a dorsal and a ventral).

The genus _Conchidium_ is the most common form of all Concharida, and some of its species occur in great numbers in the tropical zone of the Pacific and the Atlantic, on the surface as well as at various depths. It differs from the preceding _Conchellium_, its ancestral form, in the development of two caudal horns, or two strong pyramidal spines which arise from the posterior end of the valves; the dorsal horn usually is smaller than the ventral.

1. _Conchidium terebratula_, n. sp. (Pl. 124, figs. 1, 2).

Shell subspherical, smooth; both valves of nearly equal size and form, hemispherical. The three dimensive axes of the body are almost equal. Margins of the valves dentate in nearly the whole periphery; on each side of one valve eleven or twelve strong conical teeth, all of the same size. Aboral hinge with two short and stout four-sided pyramidal horns of equal length. Mouth with two equal short lips. Pores of the shell subregular, circular, three to four times as broad as the bars, in the dorsal valve twice as large as in the ventral valve.

_Dimensions._--Diameter of the shell 0.24 to 0.28.

_Habitat._--Central Pacific, Stations 270 to 274, surface, and at various depths.

2. _Conchidium thecidium_, n. sp. (Pl. 124, fig. 6).

Shell subspherical, slightly compressed on both sides. Dorsal valve somewhat smaller than the ventral, of similar form. Principal axis of the shell somewhat longer than the sagittal, and this longer than the frontal axis. Margins of the valves smooth in the oral quarter, strongly dentate in the remainder; on each side of one valve eight or nine very large triangular teeth, half as long as the height of the valve. Aboral hinge with two unequal, stout, four-sided pyramidal horns; the dorsal horn half as long at the ventral. Mouth with two unequal lips, the upper shorter than the lower. Pores of the shell subregular, hexagonal, three to four times as broad as the bars. The figured specimen, well preserved, contained in the central capsule two nuclei, one in the dorsal, the other in the ventral half.

_Dimensions._--Length of the shell 0.28 to 0.33, height 0.27 to 0.3, breadth 0.22 to 0.24.

_Habitat._--South Pacific, Station 292, depth 1600 fathoms.

{1722}3. _Conchidium rhynchonella_, n. sp. (Pl. 124, fig. 3).

Shell with three different dimensive axes in the proportion = 6 : 5 : 4. Ventral valve semi-ovate, larger than the humpbacked dorsal valve. Margins of the valves dentate almost in the whole periphery; on each side of one valve twelve or thirteen strong conical teeth. Aboral hinge with two very unequal horns, the dorsal much smaller than the pyramidal ventral. Under lip of the mouth emarginate, much larger than the acute upper lip. Pores subregular, circular, twice as broad as the bars.

_Dimensions._--Length of the shell 0.3, height 0.25, breadth 0.2.

_Habitat._--North Pacific, Stations 244 to 253, surface, and at various depths.

4. _Conchidium dimerella_, n. sp.

Shell laterally compressed, very similar to the preceding, but differing in the following characters:--Proportion of the three axes = 7 : 5 : 4. Ventral valve hemispherical, larger than the humpbacked dorsal. Margins of the valves dentate in the middle half only, whilst the anterior and posterior quarters are smooth; on each side of one valve six or seven strong conical teeth. Ventral horn of the aboral hinge very large, pyramidal, one-third as long as the shell and three times as long as the dorsal.

_Dimensions._--Length of the shell 0.35, height 0.25, breadth 0.2.

_Habitat._--North Pacific, Station 236, surface.

5. _Conchidium leptæna_, n. sp. (Pl. 124, figs. 4, 5).

Shell laterally compressed, with three different dimensive axes of the proportions = 4 : 3 : 2. Ventral valve larger than the dorsal, both semi-ovate. Margins of the valves dentate along the lateral sides; on each side of one valve nine or ten conical teeth, the middle of which are smaller. Aboral hinge with two unequal short horns; the dorsal rudimentary. Under lip of the mouth pointed, much larger than the truncate upper lip. Pores circular, about twice as broad as the bars.

_Dimensions._--Length of the shell 0.2, height 0.15, breadth 0.1.

_Habitat._--Central Pacific, Stations 271 and 272, surface, and at various depths.

6. _Conchidium argiope_, n. sp. (Pl. 124, figs. 7-9).

Shell laterally compressed, with three different dimensive axes of the proportion = 6 : 5 : 3. Both valves nearly equal. Margins of the shell dentate along the lateral fissure, on each side of one valve thirteen or fourteen thin conical teeth. Aboral hinge with two equal, short, pyramidal horns. Mouth with two equal short lips. Pores subregular, circular, twice as broad as the bars.

_Dimensions._--Length of the shell 0.2, height 0.17, breadth 0.1.

_Habitat._--Tropical Atlantic, Stations 341 to 349, surface, and at various depths.

{1723}7. _Conchidium magasella_, n. sp.

Shell laterally compressed, with two equal valves, very similar to the preceding species, but differing in the following characters:--Proportion of the three axes = 6 : 4 : 3. Margins of the valves with smaller and more numerous teeth; on each side of one valve sixteen to eighteen short conical teeth. Pores smaller and more numerous, about as broad as the bars.

_Dimensions._--Length of the shell 0.24, height 0.16, breadth 0.12.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

8. _Conchidium productum_, n. sp.

Shell laterally compressed, prolonged, with two equal valves, similar to the two preceding species, differing in the following characters:--Proportion of the three axes = 3 : 2 : 1. Margins of the valves smooth in the anterior and posterior quarter, dentate in the middle lateral half; on each side of one valve ten to twelve strong conical teeth. Horns of the aboral hinge prolonged, conical, half as long as the shell, the ventral somewhat larger than the dorsal. Pores regular, circular, twice as broad as the bars.

_Dimensions._--Length of the shell 0.25, height 0.15, breadth 0.08.

_Habitat._--North Atlantic, Station 354, surface.

Genus 724. _Conchonia_,[340] n. gen.

_Definition._--#Concharida# with the lateral margins of the valves dentate, without sagittal keel, but with an apical horn on the poles of the sagittal axis, and with two caudal horns on the hinge (a dorsal and a ventral).

The genus _Conchonia_ is closely allied to the preceding _Conchidium_, its ancestral form, but differs from this and from all other Concharida in the development of horns on the poles of the sagittal axis. These are probably of great morphological importance, since they represent the beginnings of the hollow tubes arising from the poles of the sagittal axis in all Coelodendrida and Coelographida. In one of the three observed species each valve possessed an apical or sagittal horn, whilst in the two other species one valve only was provided with a horn. Since I observed one specimen only of each species, I cannot say whether this difference is important and of constant generic value.

1. _Conchonia diodon_, n. sp. (Pl. 124, figs. 10-12).

Shell laterally compressed, with two very unequal valves. Dorsal valve smaller, hat-shaped, on the apex with a fenestrated protuberance which is similar to the galea of the Coelodendrida, and bears a short, conical, backwardly-directed horn. Ventral valve larger, boat-shaped, without apical {1724}horn. Aboral hinge with two pyramidal, horizontal, caudal horns of different sizes, the dorsal smaller than the ventral. Lateral margin of each valve on one side with twelve to fourteen strong conical teeth (fig. 12). Lips of the narrow mouth thickened (fig. 11).

_Dimensions._--Length of the shell 0.3, height 0.27, breadth 0.21.

_Habitat._--Tropical Atlantic, Station 342, depth 1445 fathoms.

2. _Conchonia triodon_, n. sp. (Pl. 124, figs. 13, 14).

Shell laterally compressed, with two very unequal valves. Dorsal valve (fig. 14) larger, hat-shaped, on the apex with a large pyramidal horn which is half as long as the shell, curved and directed backwards. Ventral valve (fig. 13) smaller, boat-shaped, without apical horn. Aboral hinge with two pyramidal caudal horns of different sizes, the dorsal horn twice as long as the ventral. Lateral margin of each valve on one side with twelve to fifteen conical teeth. Perhaps the larger horned valve (fig. 14) may be the ventral, and the opposite smaller hornless (seen from above in fig. 13) the dorsal valve.

_Dimensions._--Length of the shell 0.21, height 0.17, breadth 0.12.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

3. _Conchonia tetrodon_, n. sp.

_Conchura tetrodon_, Haeckel, 1882, Manuscript.

Shell subspherical, with two nearly equal hemispherical valves, which are very thin-walled and similar in structure to those of the Coelodendrida, with very irregular roundish pores of different shapes and sizes (compare Pl. 121, fig. 3). Lateral margins of the valves with very numerous and irregular, thin, bristle-shaped teeth, similar to those of some Coelographida (compare Pl. 127, fig. 8). Aboral hinge with two equal, conical, caudal horns, which are straight, parallel, and half as long as the shell. Two similar straight conical horns are opposed on the poles of the sagittal axis, and arise from the apex of the two valves. This remarkable species may perhaps better represent a separate genus, _Conchura_, forming a direct transition to the ancestral form of the Coelodendrida, _Coelodoras_; it differs from the latter in the absence of a galea or hollow conical cupola on the apex of each valve, and in the solid, not hollow structure of the horns.

_Dimensions._--Diameter of the shell 0.24, length of the two sagittal horns 0.1, of the two caudal horns 0.12.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.

Genus 725. _Conchopsis_,[341] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Concharida# with dentate lateral margins and a sharp sagittal keel of the compressed valves, without horns on the hinge.

{1725}The genus _Conchopsis_ and the following _Conchoceras_ differ from the other Concharida in the strong lateral compression of the shell, so that each valve is provided in the sagittal plane with a sharp prominent keel, comparable to the dorsal and the anal fin of fishes. These compressed shells are in general twice to three times as large as the more roundish and keelless shells of the five preceding genera. The sculpture of the fenestrated valves is extremely elegant. _Conchopsis_ possesses at the aboral hinge not the two prominent caudal horns, which mark the following genus _Conchoceras_, but in some species a peculiar ligament connects the aboral ends of both valves.

1. _Conchopsis orbicularis_, n. sp. (Pl. 125, fig. 3).

Shell subcircular, lenticular, strongly compressed on both sides, nearly as high as long, its sagittal perimeter nearly circular; frontal and cinctural perimeter spindle-shaped. Borders of the two boat-shaped valves smooth in 0.4 of the oral part, and in 0.1 of the aboral part of their length, strongly dentated in the remaining 0.5 middle part; about twenty-five slender, straight teeth on each side of one valve, size of the teeth increasing from the aboral towards the oral pole. In the half lateral perimeter of the shell (along the right and the left borders of each valve) sixty to sixty-five pores, in the half sagittal perimeter (along the keel of each valve) eighty to eighty-five pores, in the half equator sixty to sixty-five pores.

_Dimensions._--Length of the shell 0.53, height 0.55, breadth about 0.2.

_Habitat._--South Atlantic, west of Tristan da Cunha, Station 333, depth 2025 fathoms.

2. _Conchopsis compressa_, n. sp. (Pl. 125, figs. 7, 8).

Shell lenticular, strongly compressed on both sides; proportion of its longitudinal diameter to the sagittal and lateral = 10 : 9 : 3, its sagittal perimeter elliptical (fig. 7), cinctural and frontal perimeter spindle-shaped (fig. 8). Borders of the two boat-shaped valves smooth in 0.3 of the oral, and 0.3 in the aboral part, dentated in the remaining 0.4 middle part; about forty to forty-four very slender teeth of equal size on one lateral edge of each valve. In the half frontal perimeter of the shell (along the border of the valve) sixty-four to sixty-eight pores, in the half sagittal perimeter (along one valve-keel) seventy to eighty pores, in the half equator forty-four to forty-eight pores. Ventral and dorsal pores linear, three to four times as long as the circular, lateral pores.

_Dimensions._--Length of the shell 0.6 to 0.8, height 0.55 to 0.72, breadth 0.2 to 0.3.

_Habitat._--North Pacific, between 30° and 40° north latitude (between Japan and San Francisco), in depths from 2000 to 3000 fathoms frequent, Stations 241 to 252.

3. _Conchopsis carinata_, n. sp. (Pl. 123, fig. 8).

Shell subcircular, lenticular, in the central half slightly compressed, nearly spherical, in the peripheral half strongly compressed, with a broad, hyaline, smooth keel on the sagittal plane. Borders of the two valves smooth in the 0.2 of the oral, and 0.1 of the aboral part, strongly {1726}dentated in the remaining 0.7 middle part; about fifty slender teeth of equal size on one lateral edge of each valve. In the half lateral perimeter of the shell about forty-five to fifty pores, in the half sagittal perimeter sixty-five to seventy, in the half equator thirty-two to forty pores. The pores are arranged in parallel curved rows, which are separated by high denticulate crests. Aboral hinge with a strong ligament.

_Dimensions._--Length of the shell 0.6 to 0.7, height 0.55 to 0.65, breadth 0.35 to 0.45.

_Habitat._--South Atlantic (east of Patagonia), Station 318, depth 2040 fathoms.

4. _Conchopsis lenticula_, n. sp. (Pl. 123, fig. 9).

Shell subcircular, lenticular, strongly compressed on both sides, with a sharp and broad hyaline keel in the sagittal perimeter. Borders of the two valves smooth in 0.3 of the oral, and 0.2 of the aboral part, strongly dentated in the remaining 0.5 middle part; about thirty strong, conical teeth on the lateral edge of each valve. In the half lateral perimeter of the shell fifty to fifty-five pores, in the half sagittal seventy to seventy-five, in the half frontal forty to forty-five pores. The large central capsule of this species fills up the posterior half of the shell-cavity, the dark green phæodium the anterior half; the latter contains numerous peculiar, longish, nucleated cells (fig. 9_a_), parasites or symbiontes (?). Aboral hinge of the shell with a strong ligament.

_Dimensions._--Length of the shell 0.7, height 0.6, breadth 0.3.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

5. _Conchopsis pilidium_, n. sp. (Pl. 125, fig. 9).

Shell ovate, lenticular, compressed on both sides, with a broad, wing-like sagittal keel. Proportion of its longitudinal diameter to the sagittal and lateral = 6 : 5 : 3. Sagittal perimeter elliptical. Borders of the two hat-like valves smooth in 0.15 of the oral, and 0.2 of the aboral part, strongly dentated in the remaining 0.65 middle part; about twenty-five to thirty teeth of nearly equal size on one side of each valve. In the half lateral perimeter of the shell (along one border of each valve) forty-five to fifty pores, in the half sagittal perimeter (on the keel of one valve) seventy to seventy-five pores, in the half equator thirty-six to forty pores. Each pore is surrounded by a hexagonal frame. The opening of each valve in this species is bordered and partly closed by a broad, horizontal diaphragm or velum, like the deck of a boat; it is broadest on the oral side.

_Dimensions._--Length of the shell 0.78 to 0.8, height 0.66 to 0.7, breadth 0.3 to 0.4.

_Habitat._--South Atlantic, between Buenos Ayres and Tristan da Cunha, Stations 324 to 334, at depths between 1715 and 2900 fathoms.

6. _Conchopsis aspidium_, n. sp. (Pl. 125, figs. 1, 2).

Shell scutiform, strongly compressed on both sides, in the centre only lenticular, in the periphery wing-like, keeled. Proportion of the longitudinal diameter to the sagittal and frontal = 6 : 5 : 2. Sagittal circumference in the oral half semicircular, in the aboral half pentagonal, two {1727}acute corners jutting out near the aboral hinge, one corner in the keel of the dorsal, the outer in the keel of the ventral valve. Borders of the two boat-shaped valves smooth in 0.3 of the oral part, and in 0.1 of the aboral part, strongly dentated in the remaining 0.6 middle part; about thirty-five teeth in one side of each valve, larger on both ends than in the middle. In the half frontal perimeter of the shell sixty to sixty-five pores, in the half sagittal perimeter eighty to eighty-five, in the half equator of the shell forty to fifty pores.

_Dimensions._--Length of the shell 0.55 to 0.65, height 0.5 to 0.55, breadth 0.2 to 0.22.

_Habitat._--North Pacific, Stations 243 and 244, depth 2800 to 2900 fathoms.

7. _Conchopsis navicula_, n. sp. (Pl. 125, figs. 4-6).

Shell pear-shaped, compressed on both sides, in the sagittal periphery keeled. Proportion of the longitudinal diameter to the sagittal and lateral = 4 : 3 : 2. Its sagittal perimeter nearly ovate. Borders of the two boat-shaped valves smooth in 0.3 of the oral, and 0.15 of the aboral part, strongly dentated in the remaining 0.55 middle part; teeth conical, of nearly equal size. In the half frontal perimeter of the shell (along one border of each valve) forty to forty-five pores, in the half sagittal fifty-four to fifty-six pores, in the half equator thirty-two to thirty-six pores. Each pore is surrounded by a hexagonal frame, and pierces the shell in an oblique direction, dilated in the middle part (figs. 5, 6). Shell very thick-walled, several longitudinal crests on both sides of the keel of each valve. Hinge very strong, usually with a broad ligament between the two unequal aboral lips of the hinge.

_Dimensions._--Length of the shell 0.8, height 0.6, breadth 0.4.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

Genus 726. _Conchoceras_,[342] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Concharida# with dentate lateral margins and a sharp sagittal keel of the compressed valves, and with two caudal horns on the hinge (a dorsal and a ventral).

The genus _Conchoceras_ has the same lenticular keeled and laterally compressed shell as the preceding ancestral genus _Conchopsis_, but is distinguished from it by the development of two large caudal horns on the aboral hinge. It bears therefore the same relation to the latter as _Conchidium_ does to _Conchellium_.

1. _Conchoceras caudatum_, n. sp. (Pl. 124, fig. 15).

Shell lenticular, slightly compressed; proportion of the longitudinal diameter to the sagittal and lateral = 6 : 5 : 4; sagittal and cinctural perimeter ovate, frontal perimeter elliptical. Free {1728}margins of the two boat-shaped valves dentate nearly in the whole perimeter; in one lateral border of each valve eleven or twelve very large conical teeth, the largest of which are nearly half as high as the valve. On the aboral hinge of the shell two divergent, very large horns, four-sided pyramidal, acute, straight, at the base perforated by a few large pores. The dorsal horn (of the smaller valve) is somewhat shorter than the ventral horn (of the larger valve). The apical distance of both horns is somewhat greater than their length, and about half the length of the shell. In the half frontal perimeter (along one border of each valve) thirty-two to thirty-four pores, in the half sagittal perimeter thirty-four to thirty-eight, in the half equator thirty to thirty-three. The pores are smaller near the girdle-fissure, irregularly quadrangular, and arranged in longitudinal rows, which are separated by meridional crests, and converge towards both poles of the main axis.

_Dimensions._--Length of the shell (without the horns) 0.24 to 0.26, height 0.20 to 0.22, breadth 0.16 to 0.18; length of the horns 0.1 to 0.13.

_Habitat._--Eastern part of the Tropical Atlantic, near the Equator, Station 348, depth 2450 fathoms.

2. _Conchoceras cornutum_, n. sp. (Pl. 124, fig. 16).

Shell lenticular, strongly compressed on both sides; proportion of the longitudinal axis to the sagittal and lateral = 4 : 3 : 2. Sagittal perimeter ovate, frontal perimeter elliptical, cinctural perimeter spindle-shaped. Free margins of the two keeled valves in the oral third smooth, in the remaining part strongly dentate; ten or eleven large teeth on one lateral border of each valve, the largest about half as high as the valve. On the aboral hinge of the shell two fenestrated apophyses which bear two stout, strongly curved horns, like pincers; the dorsal horn (of the smaller upper valve) is shorter and less curved than the ventral horn (of the larger lower valve). The lips of the mouth (at left on fig. 16) are also unequal, the upper lip emarginate. In the half frontal perimeter of the valve twenty-two to twenty-four pores, in the half sagittal perimeter twenty-eight to thirty, in the half equator twenty to twenty-two. The pores are separated by high parallel crests and arranged in longitudinal rows, which converge towards the aboral hinge.

_Dimensions._--Length of the shell (without the horns) 0.36 to 0.4, height 0.27 to 0.3, breadth 0.2 to 0.22; length of the horns 0.16 to 0.22.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.

Family LXXXIV. #COELODENDRIDA#, Haeckel (Pl. 121).

_Coelodendrida_, Haeckel, 1862, Monogr. d. Radiol., p. 360.

_Definition._--PHÆODARIA with a bivalved lattice-shell, composed of two hemispherical valves, a dorsal and a ventral. A conical cupola or a pyramidal galea arises from the apical pole of both valves, therefore at the opposite poles of the sagittal axis. Rhinocanna and frenula wanting. Three or more hollow radial tubes arise from each valve and are symmetrically disposed. Sometimes their branches form an outer {1729}bivalved mantle. The central capsule is so enclosed between the two inner valves, that its three openings lie in the open frontal fissure between them.

The family #Coelodendrida# differs from the preceding Concharida (its probable ancestral group) in the development of a conical galea or pyramidal cupola on the apical pole of each valve, and of three or more hollow radial tubes arising from each galea. They do not possess, however, the peculiar sagittal nasal tube or rhinocanna, which is constantly developed from the base of each cupola (and connected with its apex by a frenulum) in the following family, the Coelographida. These latter differ also from the former in the constant possession of prominent verticillate styles.

The family Coelodendrida was founded in 1862 in my Monograph (p. 360) and represented hitherto only by two species of the genus _Coelodendrum_, there described (p. 361, Taf. xiii. figs. 1-3, and Taf. xxxii. fig. 1). This first description, however, contained some errors, which were afterwards (in 1879) corrected by Richard Hertwig; this author also gave the first accurate description of the central capsule and its three openings. In the rich collection of the Challenger, the Coelodendrida are represented by four genera, but only seventeen species, some of which, however, are cosmopolitan and very common, particularly _Coelodendrum_.

The two valves of the lattice-shell, dorsal and ventral, are either hemispherical, or somewhat more flatly vaulted or cap-shaped. They are never connected in the equatorial zone of the body, as I supposed in my Monograph (1862, _loc. cit._); but they are separated by the girdle-fissure, a free circular equatorial interval, in which lie the three openings of the enclosed central capsule. Though the two valves, therefore, have no direct connection, they are, however, always opposed so accurately, that their equal free circular edges correspond exactly one to the other, so that the apex of each valve lies in one pole of the sagittal axis. From this apex there arises on each valve an irregular conical or three-sided pyramidal cupola, the galea (Pl. 121, figs. 3, 4, 8). The Coelodendrida differ in the possession of this galea from the Concharida, and agree with the Coelographida; but they never exhibit the peculiar rhinocanna or nasal tube, which arises from each galea in the latter family.

The siliceous lattice-plate of the two valves, and of the galea arising from them, is very thin and fragile, and its irregular roundish pores are extremely variable in size, number, and disposition. Sometimes the pores are so small and so scarce, that the plate appears nearly solid. At other times the siliceous plate seems to be really solid, and covered by a network of thin crests, the small dimples between which give to it the appearance of being fenestrated. Often the pores or the dimples are wanting in the central part of each valve, while they are very numerous and dense in the peripheral part. The same may be said of the lattice-plate of the galea, which is sometimes nearly solid, at other times richly fenestrated. The Coelodendrida agree in this structure with the following {1730}family, the Coelographida, and differ from the preceding family, the Concharida, in which the siliceous wall of the two valves is much thicker, and perforated by regular circular or roundish pores.

The galea or conical cupola in the apex of the two valves ("der kegelförmige Aufsatz" of the German authors) has in all Coelodendrida a triangular base and an irregularly conical or nearly three-sided pyramidal form. Its cavity is about one-third or one-fourth as large in diameter as the cavity of the hemispherical valve upon which it rests. The galea is relatively smaller and more irregularly formed than in the Coelographida, and differs essentially from that of the latter in the constant absence of a rhinocanna; there are also wanting, therefore, the characteristic frenula, which connect the nasal tube with the apex of the galea. The cavity of the galea probably always communicates with that of the valves by pores in the separating siliceous plate, and is besides pierced by irregular pores in its outer wall, very variable in form, size, and number, but it does not communicate with the cavity of the hollow radial tubes, from which it is separated by a thin, solid, siliceous plate.

The hollow radial tubes which arise from the galea in the Coelodendrida do not seem to possess that constant regularity in number, origin, and disposition, which is found in the following family, and there serves for distinction of genera. In my first description of the Coelodendrida (1862, _loc. cit._, p. 362), I pointed out this irregularity, and mentioned that the number of radial tubes arising from each galea varies from three to eight; the total number therefore amounts to from six to sixteen, the same minimum and maximum numbers which we shall encounter also in the radial styles of the following family. But whilst it is easy to determine the position and relation of these hollow tubes in the Coelographida, owing to the constant sagittal position of their rhinocanna, this task is very difficult in the Coelodendrida, where the rhinocanna is wanting. In the most frequent cases there arise from each galea three or four tubes, more rarely five or six, and very rarely seven or eight. The simplest and probably the original case is the development of three tubes, two of which are paired (divergent on the right and left), while the third is odd, lying in the sagittal plane. Perhaps these three primary tubes may be compared to the three cortinar feet of the NASSELLARIA, so that we may regard the two paired anterior as pectoral, and the odd posterior as a caudal tube. Usually the two paired or pectoral tubes arise from two corners of the triangular base of the galea, whilst the third odd or caudal tube does not arise from the third corner of the base, but more or less above it, and often even from the highest point or the apex of the galea. In the majority of species observed, this odd sagittal tube is forked even at its origin, so that two divergent tubes (an anterior and a posterior) arise from the apex of the galea (Pl. 121, figs. 3, 8). More rarely the two paired or pectoral tubes are also forked at the base, so that three pairs of tubes arise from each galea, and the total number of tubes amounts to twelve. Very rarely {1731}four separate tubes or four pairs of tubes arise from each galea, viz., two from the two anterior corners of the basal triangle, one from the posterior corner, and one from the apex of the galea. It is possible that this difference in the origin, furcation, and number of the hollow radial tubes may be employed for the distinction of genera of Coelodendrida, in the same manner as it is employed in the next following family, the Coelographida. But I have not been able, in spite of numerous and accurate examinations, to demonstrate in the former the same regularity in number and arrangement of the tubes as in the latter. It seems that these relations here are very variable, even in one and the same Species, and not yet fixed.

It is, however, probable, on the other hand, that the primary tubes (all or partly) are identical to the Coelodendrida and Coelographida. This is most probably the case with the posterior odd or caudal tube, which seems to be never wanting, and in both families is developed in the form of a dichotomous brush (never in the form of a verticillate style). Possibly also the two paired pectoral tubes are homologous in both families.

The hollow tubes are perfectly simple and unbranched only in one genus, _Coelodoras_, which is probably the common ancestral form of both families, and which may have been derived from _Concharium_ by development of a galea and tubes on the sagittal apex of the valves. All the other Coelodendrida have branched spines, and the ramification is constantly dichotomous, or repeatedly forked. There never occur in this family those characteristic "styles," or verticillate prolonged tubes, which we find in all Coelographida. Usually the cylindrical tubes are slightly curved and forked even near their base. The furcation is repeated a variable number of times in the different species. In the largest species each tube becomes a brush with more than one hundred terminal bristles.

We divide the Coelodendrida into two subfamilies, according to the different development of the distal branches of the hollow tubes. In the Coelodorida all the branches of the tubes remain free and are never connected by anastomoses, so that the surface of the bivalved skeleton is protected by the free radial distal branches of the tubes. In the larger species of _Coelodendrum_ (_e.g._, _Coelodendrum furcatissimum_, Pl. 121, fig. 1), the numerous branches of the dichotomous tubes form a dense thicket, similar to that in the Coelotholida.

In the second subfamily, Coelodrymida, the distal branches of the tubes are connected by numerous anastomoses, and compose either a simple lattice-plate on the surface of the skeleton (_Coelodrymus_), or a thicker envelope of spongy framework (_Coelodasea_). The lattice-mantle so produced is always bivalved, and its two outer hemispherical valves (dorsal and ventral) correspond exactly to the two inner valves, from which arise the hollow tubes. The free margins of the two external mantle-valves come externally into contact in the equatorial plane of the body, in which the girdle-fissure lies internally between the two central shell-valves. The free edges {1732}of the two external mantle-valves, opposed to one another in the circle of the equator, seem usually to catch one into another in the same way as the corresponding mantle-valves of the Coeloplegmida are loosely connected (Pl. 128, figs. 1, 7). A true concrescence between the two valves seems never to take place.

The two subfamilies of Coelodendrida therefore exactly correspond to the two subfamilies of the following family, the Coelographida. The Coelodorida and Coelotholida form in a similar way a thicket, by dichotomous ramification of the hollow tubes, all the branches of which remain free. The Coelodrymida and Coeloplegmida, on the other hand, form an outer lattice-mantle by anastomosing branches. The latter two subfamilies, of course, have been derived correspondingly from the two former, and the common ancestral form of all four is probably _Coelodoras_, derived from the Concharida.

Though the two corresponding subfamilies in both groups are very similar, they are, however, separated by important hereditary characters. All Coelodendrida (the Coelodorida without a mantle as well as the Coelodrymida with a mantle) possess no rhinocanna and no frenula on the galea, and they never develop prominent verticillate styles; the surface of their calymma is probably always spherical or subspherical. All Coelographida, however (the Coelotholida without a mantle as well as the Coeloplegmida with a mantle), possess a rhinocanna and frenula on the galea, and always develop prominent verticillate styles; the surface of their calymma is probably always symmetrically polyhedral.

The superficial armature of the skeleton in the Coelodendrida is rather simple, and by no means so manifold and differentiated as in the more highly developed Coelographida. The thin terminal branches of the hollow tubes are in the Coelodorida closed at the distal end, and armed with a variable number of short teeth (Pl. 121, fig. 2), or with a spinulate terminal knob, or a corona of recurved hooks (_ibid._, figs. 5-7). In the Coelodrymida, however, where the distal ends of the branches by anastomosing form the lattice-mantle, the spherical surface of this latter is armed with numerous thin spathillæ or radial bristles (often zig-zag or spinulate), and each bristle usually bears at the distal end a small anchor with two, three, or four recurved teeth; the outer convex edge of these teeth is usually smooth, the inner concave edge denticulate. All these ramules and branches of the tubes (also the thinnest terminal threads) are hollow, and filled up by jelly.

The _central capsule_ of the Coelodendrida does not lie outside the two central valves (as I supposed in my first description, in 1862, being deceived by the dark enveloping phæodium, Monogr. d. Radiol., Taf. xxxii. fig. 1), but it is enclosed between the two valves, as in the preceding and the following family. The first accurate description of it was given by Richard Hertwig in 1879 (_loc. cit._, p. 95, Taf. x. fig. 3). Its constant position between the two lattice-valves (dorsal and ventral) is such, that its three openings lie in the frontal plane, in the open fissure between the valves. The astropyle or the main-opening, with the radiate operculum and the tubular proboscis arising from it, lies on the anterior (or oral) {1733}pole of the main axis, whilst the two lateral accessory openings, or parapylæ, lie on both sides of the posterior (or aboral) pole, to the right and left. The position of the capsule is therefore the same as in the preceding Concharida (Pls. 123-125), and the following Coelographida (Pls. 126-128). The large nucleus, enclosed in the central capsule, is usually half as broad, and contains numerous nucleoli.

The calymma, or the extracapsular jelly-veil, is in the Coelodendrida usually spherical, very voluminous, and includes the entire skeleton, the thicket of the Coelodorida as well as the lattice-mantle of the Coelodrymida. Only the outermost terminal branches of the tubes in the former, and the radial bristles and spathillæ on the surface of the latter, remain free and project beyond the surface of the calymma. The phæodium is usually very large, three to four times as broad as the central capsule, and envelops it often completely. Usually it envelops only the anterior half of it, and the proboscis (Pl. 121, figs. 1, 9). Often numerous green, brown, or blackish phæodellæ are scattered through the whole calymma, and sometimes accumulate in a superficial layer on its surface. The galea of both valves is usually also filled up by the phæodium.

_Synopsis of the Genera of Coelodendrida._

------------------------------------------------------------------------- I. Subfamily Coelodorida. Hollow tubes, arising from the galea of both valves, simple or dichotomously branched; the branches always free, not anastomosing. No outer lattice-mantle. ------------------------------------------------------------------------- Tubes simple, not branched, 727. _Coelodoras_.

Tubes forked or dichotomously branched, 728. _Coelodendrum_. ------------------------------------------------------------------------- II. Subfamily Coelodrymida. Hollow tubes, arising from the galea of both valves, dichotomously branched; the branches anastomose and form an outer bivalved lattice-mantle. ------------------------------------------------------------------------- Lattice-mantle simple; its meshes lying in a spherical surface, 729. _Coelodrymus_.

Lattice-mantle spongy; its meshes lying in different planes, 730. _Coelodasea_.

Subfamily I. COELODORIDA, Haeckel.

_Definition._--#Coelodendrida# without an external bivalved lattice-mantle, with simple or branched hollow tubes, the terminal branches of which are free, not anastomosing.

Genus 727. _Coelodoras_,[343] n. gen.

_Definition._--#Coelodendrida# without external lattice-mantle, with simple, not branched, radial tubes, which arise separately from the galea.

{1734}The genus _Coelodoras_ is the simplest form of the Coelodendrida, and may be regarded as the common ancestral form of this and of the following family. It differs from all other members of these two families in the simple shape of the hollow radial tubes which arise from the galea, and are neither branched nor forked; the galea is very small, a flat triangular cap. _Coelodoras_ may be derived immediately from _Concharium_ or _Conchonia_ (p. 1723), by development of the galea and the radial tubes.

1. _Coelodoras hexagraphis_, n. sp.

Three straight, cylindrical, equidistant hollow tubes arise divergent from the three corners of each galea, and are about as long as the diameter of the valves, at the distal end armed with a spinulate knob. The odd sagittal (or caudal tube) is directed backwards, the two paired (or pectoral) tubes, forwards.

_Dimensions._--Diameter of the valves 0.16, length of the tubes 0.2.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.

2. _Coelodoras octographis_, n. sp.

Four hollow cylindrical tubes, slightly curved, arise divergent from each galea, and are about one and a half times as long as the diameter of the valves, at the distal end knob-shaped, and armed with four crossed, recurved teeth. Two anterior (or pectoral) tubes arise from the two frontal corners of the galea basis, and diverge forwards to right and left. Two posterior tubes (a sagittal and a caudal) arise from the posterior corner of each galea, and diverge in the sagittal plane backwards.

_Dimensions._--Diameter of the valves 0.2, length of the tubes 0.3.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.

Genus 728. _Coelodendrum_,[344] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 801.

_Definition._--#Coelodendrida# without external lattice-mantle, with branched radial tubes, the hollow branches of which are free and never connected by anastomoses.

The genus _Coelodendrum_ is the first described form not only of the family Coelodendrida, but of all #Phæoconchia# or bivalved PHÆODARIA; it is also the most common form of this group, and represented by ten different species, some of which are cosmopolitan, very common, and widely distributed. In my first description of _Coelodendrum_ I confounded it erroneously with some forms of _Coelodasea_ and _Coelographis_, the separated fragments of which I had found entangled between the branches of the former. The first figures of _Coelodendrum_ are given in my Monograph, in 1862, {1735}Taf. xiii. figs. 1-3 (not 4) and Taf. xxxii. fig. 1 (not 2 and 3). _Coelodendrum_ has been derived from _Coelodoras_ by furcation and repeated dichotomous ramification of the hollow radial tubes which arise from the galea.

Subgenus 1. _Coelodendridium_, Haeckel.

_Definition._--Ramification of the hollow tubes regularly dichotomous, each branch being forked again; therefore the two terminal ramules of the last branches equal.

1. _Coelodendrum ramosissimum_, Haeckel.

_Coelodendrum ramosissimum_, Haeckel, 1862, Monogr. d. Radiol., p. 363, Taf. xiii. figs. 1-3.

_Coelodendrum ramosissimum_, R. Hertwig, 1879, Organism. d. Radiol., p. 93, Taf. x. figs. 3, 12.

Terminal branches regularly forked, with two equal, smooth, nearly straight or slightly curved fork-branches, diverging at right angles; their end-knobs with four crossed (or sometimes five or six) short recurved teeth.

_Dimensions._--Diameter of the spherical skeleton 1.2 to 1.8, of the two central valves 0.2 to 0.25.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; many Stations, surface and at various depths.

2. _Coelodendrum spinosissimum_, n. sp. (Pl. 121, fig. 7).

Terminal branches regularly forked, with two equal, smooth, straight, fork-branches, diverging at right angles, their end-knobs echinoidal, subspherical or club-shaped, with numerous short radial thorns.

_Dimensions._--Diameter of the skeleton 2 to 2.2, of the two central valves 0.25 to 0.03.

_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.

3. _Coelodendrum furcatissimum_, n. sp. (Pl. 121, fig. 1-4).

Terminal branches regularly forked, with two equal, smooth, straight, or slightly curved fork-branches, diverging at acute angles; their end-knobs very small, with three short, diverging, conical teeth.

_Dimensions._--Diameter of the skeleton 2 to 2.5, of the two central valves 0.3 to 0.4.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific; many Stations, surface, and at various depths.

4. _Coelodendrum bifurcum_, n. sp.

Terminal branches regularly forked, with two equal, smooth, more or less curved fork-branches, diverging at acute angles; their end-knobs thin, with two slender, parallel, bristle-shaped teeth.

_Dimensions._--Diameter of the skeleton 0.6 to 0.8, of the two central valves 0.1 to 0.15.

_Habitat._--North Pacific, Stations 252 to 256, surface.

{1736}5. _Coelodendrum gracillimum_, Haeckel.

_Coelodendrum gracillimum_, Haeckel, 1862, Monogr. d. Radiol., p. 364, pl. xxxii. fig. 1.

Terminal branches regularly forked, with two equal, spinulate, curved fork-branches, diverging at obtuse angles and covered with numerous small thorns; their end-knobs cap-shaped, with a corona of six to eight small recurved teeth. In one specimen of this species (in 1859) I found entangled the fragments of _Coelographis gracillima_, figured in Taf. xxxii. figs. 2, 3, _loc. cit._ I supposed at that time, erroneously, that the latter belonged to full-grown specimens of the former.

_Dimensions._--Diameter of the skeleton 1 to 1.2, of the valves 0.15 to 0.2.

_Habitat._--Mediterranean (Messina), surface.

6. _Coelodendrum lappaceum_, n. sp.

Terminal branches regularly forked, with two equal, spinulate, straight or slightly curved fork-branches, diverging at acute angles and covered with small recurved hooks; their end-knobs large, conical, with a prominent apex and a basal corona of six to eight recurved teeth.

_Dimensions._--Diameter of the skeleton 1.5 to 1.8, of the valves 0.22.

_Habitat._--South Pacific, Stations 285 to 295, depth 1500 to 2600 fathoms.

Subgenus 2. _Coelodendronium_, Haeckel.

_Definition._--Ramification of the hollow tubes more or less irregular, mainly in the periphery; the terminal ramules of the last branches unequal.

7. _Coelodendrum cervicorne_, n. sp. (Pl. 121, fig. 8).

Terminal branches irregularly ramified, with unequal, smooth, curved ramules, diverging at obtuse angles, their end-knobs echinoidal, small, with short, diverging, conical thorns.

_Dimensions._--Diameter of the skeleton 1 to 1.2, of the valves 0.2.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

8. _Coelodendrum digitatum_, n. sp.

Terminal branches irregularly ramified, with unequal, spinulate, straight ramules, diverging at acute angles; the two last fork-branches digitate, each with five diverging finger-shaped ramules, lying in a meridian plane; their end-knobs conical, pointed, with a corona of recurved hooks.

_Dimensions._--Diameter of the skeleton 1.6, of the valves 0.24.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

{1737}9. _Coelodendrum flabellatum_, n. sp. (Pl. 121, fig. 6).

Terminal branches flabellate, irregularly ramified, each of the last two fork-branches being divided into four or five diverging straight branches of different lengths; usually the last eight or ten ramules lie in a meridional plane; their end-knobs cap-shaped, with a corona of recurved teeth.

_Dimensions._--Diameter of the skeleton 2.0 to 2.5, of the valves 0.25 to 0.3.

_Habitat._--North Pacific, Station 235 to 240, surface.

10. _Coelodendrum serratum_, n. sp. (Pl. 121, fig. 5).

Terminal branches flabellate, irregularly ramified like the preceding species; it differs from this in the strong compression of the broad, saw-shaped, terminal branches; the two opposite edges (placed in the meridional plane of the flabellum) are finely serrated; their end-knobs with a corona of diverging teeth.

_Dimensions._--Diameter of the skeleton 3.0 to 3.2, of the valves 0.3 to 0.36.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

Subfamily 2. COELODRYMIDA, Haeckel.

_Definition._--#Coelodendrida# with an external bivalved lattice-mantle, produced by the anastomosing branches of the hollow radial tubes.

Genus 729. _Coelodrymus_,[345] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Coelodendrida# with an external bivalved lattice-mantle, produced by the anastomosing terminal branches of the hollow tubes, which are connected in a spherical face.

The genus _Coelodrymus_, and the following closely allied genus _Coelodasea_, represent together the small subfamily Coelodrymida, differing from the Coelodorida in the possession of an outer bivalved lattice-mantle. They exhibit therefore the same relation to the latter, that in the following family the Coeloplegmida bear to the Coelotholida. The bivalved spherical mantle is composed of a simple lattice-plate in _Coelodrymus_, of a spongy framework in _Coelodasea_; the anastomosing branches of the hollow radial tubes become connected in the former in a spherical face, in the latter in the form of a spongy framework.

{1738}1. _Coelodrymus ancoratus_, n. sp. (Pl. 121, figs. 9, 10).

Network of the mantle loose, with large, irregular, polygonal meshes; the terminal branches of the forked trees, which communicate at the spherical surface of the calymma, and compose the mantle, are smooth. Spherical surface covered with very numerous and thin zigzag radial filaments, which are about as long as the galea, and bear at the distal end an anchor with two recurved teeth, denticulate at the concave proximal edge (fig. 10).

_Dimensions._--Diameter of the spherical lattice-mantle 2 to 2.5, of the valves 0.3 to 0.4.

_Habitat._--South-Eastern Pacific (off Juan Fernandez), Station 300, depth 1375 fathoms.

2. _Coelodrymus lappulatus_, n. sp.

Network of the mantle rather dense, with numerous and small irregular polygonal meshes; the terminal branches of the forked trees, which compose the mantle, are spinulate. Spherical surface densely studded with very numerous spinulate, radial filaments, which are about half as long as the galea, and bear at the distal end an anchor with four crossed recurved teeth, denticulate at the concave proximal edge.

_Dimensions._--Diameter of the spherical lattice-mantle 2.5 to 3, of the valves 0.4 to 0.5.

_Habitat._--South-Western Pacific (east of New Zealand), Station 169, depth 700 fathoms.

3. _Coelodrymus echinatus_, n. sp.

Network of the mantle very dense, with very numerous and small irregular roundish meshes; the terminal branches of the forked trees, which compose the mantle, are spiny. Spherical surface studded with very numerous, thin, radial bristles, which bear no anchor at the distal end.

_Dimensions._--Diameter of the spherical lattice-mantle 1.8, of the valves 0.22.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

Genus 730. _Coelodasea_,[346] n. gen.

_Definition._--#Coelodendrida# with an external spongy lattice-mantle, produced by the anastomosing branches of the hollow tubes, which are connected in different heights.

The genus _Coelodasea_ differs from the preceding _Coelodrymus_ in the spongy structure of the outer bivalved mantle. The hollow branches of the radial tubes of _Coelodendrum_, which anastomose in _Coelodrymus_ only on the spherical surface of the calymma, and form a simple lattice-sphere, become connected in _Coelodasea_ in different planes (laterally and terminally), and therefore form an irregular spongy framework. The latter exhibits therefore to the former a relation similar to that which _Spongoplegma_ bears to _Carposphæra_ among the #Sphæroidea#.

{1739}1. _Coelodasea ramosissima_, Haeckel.

_Coelodendrum ramosissimum_ (_partim_), Haeckel, 1862, Monogr. d. Radiol., p. 363, Taf. xiii. fig. 4.

Spongy framework of the spherical bivalved mantle very dense and thick, produced by very numerous, irregular anastomoses of the lateral and terminal branches, which arise from the hollow tubes. The last and thinnest terminal branches are forked, as seen in the radial section of fig. 4 (_loc. cit._), their ends are closed and armed with some very small denticles (not open, as figured in fig. 4). In my Monograph I had confounded this species with _Coelodendrum ramosissimum_, which however, may possibly be its ancestral form.

_Dimensions._--Diameter of the spongy spherical mantle 2 to 2.5, of the central valves 0.15.

_Habitat._--Mediterranean (Messina), surface.

2. _Coelodasea spongiosa_, n. sp.

Spongy framework of the bivalved mantle rather loose, not nearly so thick and dense as in the preceding species. The last and thinnest terminal branches are prolonged into denticulate, zigzagged, radial filaments, which bear at their distal end an anchor with two recurved teeth (similar to _Coelodrymus ancoratus_, Pl. 121, figs. 9, 10).

_Dimensions._--Diameter of the spongy spherical mantle 3 to 3.2, of the central valves 0.24.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.

Family LXXXV. #COELOGRAPHIDA#, n. fam. (Pls. 122, 126-128).

_Definition._--PHÆODARIA with a bivalved lattice-shell, composed of two hemispherical valves, a dorsal and a ventral. A conical cupola or a helmet-shaped galea arises on the apical pole of each valve, therefore on the opposite poles of the sagittal axis. The cavity of the galea communicates with the sagittal rhinocanna, a peculiar nasal tube, which rests upon the valve, and is connected with the galea by a simple or double frenulum; its opening being directed towards the proboscis. Three or more branched hollow radial tubes arise from each valve, and are symmetrically disposed. Sometimes their branches form an outer bivalved mantle. The central capsule is so enclosed between the two inner valves, that its three openings lie in the open frontal fissure between them.

The family #Coelographida#, the last family of the PHÆODARIA, exhibits the highest degree of morphological development, not only in this group, but among all Radiolaria. They attain also the greatest size of all members of the class, since the diameter of their body is sometimes more than 20 mm., and in a few species even more than 30 mm. The complexity of their structure attains at the same time such a high degree, that they may be regarded as the most complicated, and (in a morphological sense) as the most highly developed of all Protozoa. Nevertheless their body always remains a single cell, {1740}and is closely allied to the preceding Coelodendrida; they differ from the latter mainly in the development of a peculiar new organ, the "rhinocanna," or "nasal tube." This is a hollow tube placed in the sagittal plane, arising from the base of each galea, and is connected with its apex by a simple or double frenulum. Between the oral openings of the two opposed rhinocannæ (one dorsal and one ventral) lies the proboscis of the central capsule.

The first observed species of Coelographida was _Coelographis gracillima_, some parts of which (but not the entire skeleton) were figured in my Monograph (1862, Taf. xxxii. figs. 2, 3). But I confounded these with _Coelodendrum gracillimum_, in the branched hollow trees of which the fragments of the former were entangled. I detected this error afterwards, when I had the opportunity of the observing some complete specimens. The first description of a complete skeleton was given in 1882 by O. Bütschli, who examined a large specimen of _Coelothamnus davidoffii_, captured by Davidoff in the Mediterranean (Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 486, Taf. xxxi.). In the rich collection of the Challenger I was able to distinguish not less than nine genera and twenty-six species of Coelographida, but the majority of their large and most fragile skeletons were more or less injured, or quite broken. It was, therefore, of the highest importance for the minute study of this difficult group, that Dr. John Murray, during his expedition to the Færöe Channel (in 1882, in H.M.S. "Triton"), discovered in the Gulf Stream the beautiful _Coeloplegma murrayanum_, and brought up home hundreds of well-preserved specimens (Pl. 127). Only by the complete examination of this excellent material it was possible to answer many difficult questions as to their morphology, and to correct the errors in my description and in that of Bütschli.

We divide the family Coelographida into two rather different subfamilies, which may afterwards be separated as two divergent families, the Coelotholida (Pl. 122) and Coeloplegmida (Pls. 126-128). Both groups may be easily distinguished at a glance, since the numerous branches, arising from the hollow radial tubes, remain constantly free and independent in the former, and represent a spiny thicket, whilst in the latter they constantly become united, and by anastomosing form a peculiar "mantle," or outer envelope of delicate network. But besides, there are other and more important differences between the two groups. The peculiar hollow tube, arising from the base of the galea on each valve, which is filled with phæodella, and which we call the rhinocanna, develops in the Coelotholida on its open mouth two paired lateral frenula (right and left), which connect it (like two lateral bridges) with the base of two paired hollow main tubes (the "frontal tubes"). In the Coelospathida, however, the mouth of the rhinocanna develops a single odd frenulum only (in the sagittal plane), and is connected by it with the base of an odd, single, hollow main tube, directed forwards, the "nasal style."

The central bivalve lattice-shell, from which the galea and the tubes arise, exhibits in {1741}the Coelographida essentially the same form and structure as in the preceding Coelodendrida. The only (but important) difference between them is indicated by the constant presence of the peculiar rhinocanna in the former, whilst this is always absent in the latter. The two valves of the shell, dorsal and ventral, are either hemispherical or somewhat flatter, sometimes nearly cap-shaped, and formed of an extremely delicate and irregularly fenestrated plate of silica, as in the Coelodendrida. As in the latter, so also in the Coelographida both valves are of similar form and usually of equal size, but sometimes the dorsal is a little smaller than the ventral valve. The remarkable difference which Bütschli describes in his _Coelothamnus davidoffii_, and the inverse origin of the three tubes in both valves (_loc. cit._, Taf. xxxi; figs. 2, 4), depends upon an error of observation, produced by the artificial inversion of one valve, and the dislocation of their natural arrangement. The valves are never in direct contact, but separated by the equatorial fissure or girdle-cleft, in which the girdle zone of the enclosed central capsule and its three openings lie freely (Pl. 127, figs. 4, 5; Pl. 128, fig. 2). The free margins of both valves, which are opposite to one another, and bound the girdle-cleft, are always equidistant, so that the cleft in the whole equatorial circumference is of equal breadth. The margins are usually irregularly denticulate, sometimes armed with longer bristles (Pl. 127, fig. 8), more rarely smooth (fig. 5). The delicate lattice-work of the valves is always irregular and very variable, usually with numerous small and unequal pores, sometimes rudimentary, so that the valves appear partly solid and hyaline. The size of the valves is usually between 0.2 and 0.5 (in diameter).

The galea (_g_) or the apical cupola, which arises from the vaulted apex of each valve (or its sagittal pole) is more developed in the Coelographida than in the preceding Coelodendrida, and differs from the latter in the peculiar rhinocanna arising from its base, and in the single or double frenulum, connecting the open mouth of the rhinocanna with the odd or paired main tube arising from the galea. The two opposite galeæ lie therefore on the poles of the sagittal axis of the bivalve shell, and are so symmetrically disposed in the sagittal plane, that the open mouths of their rhinocannæ are directed towards the oral pole of the main axis, and nearly come in contact with the proboscis arising from the radiate operculum of the central capsule (Pl. 127, figs. 4, 5).

The size and form of the galea are very variable, even in one and the same species. The volume of its cavity is generally about as great as that of the hemispherical valve from which it arises, sometimes larger, at other times smaller. Its fundamental form is constantly dipleuric or bilateral, since the radial hollow tubes arise symmetrically on both its sides, and the rhinocanna proceeding from its base determines the sagittal plane. Usually the galea has the form of a vaulted helmet, the convex crest of which is inclined towards the mouth (Pl. 127, figs. 4, 5, 8, 9). Its anterior or apical part is broad and truncated in the Coelotholida, more or less conical in the Coelospathida; sometimes it assumes nearly the form of a bilateral three-sided pyramid, at other times it is more {1742}pear-shaped (Pls. 126-128). The thin siliceous wall of the galea has the same irregular and delicate network as the valve from which it arises, and sometimes the small irregular pores are also here reduced, so that the wall becomes partly solid. In some cases the thin, solid, siliceous plate of the galea and of the valve is covered by an irregular delicate network of crests; the dimples between these crests may be easily confounded with true pores.

The cavity of the galea is filled with phæodella and does not communicate with the cavity of the shell-valves, nor with the cavity of the radial tubes filled by jelly; it is closed towards the latter and the former by a thin solid plate of silex. Bütschli (1882, _loc. cit._, p. 488) describes in _Coelothamnus_ a large circular opening (Taf. xxxi. figs. 2_a_, 4_a_), and states that this is a direct communication between the cavities of the valves and of their galeas which are called by him "der dreiseitige kastenförmige Aufsatz" ([epsilon]). This error was caused by the fact that he observed the valves from the apical face only. The apparent opening of communication does not exist, and is the optical section of the rhinocanna, the shortened walls of which he describes as "trapezförmige Kiesellamelle" ([gamma]); the two lateral edges of the latter ("die seitlichen Zipfel," [delta]) are the paired frenula, which connect the open mouth of the rhinocanna with the base of the two frontal tubes.

The "rhinocanna or nasal tube" (Pl. 126, figs. 1, 4; Pl. 127, figs. 4-9_t_) is a very remarkable organ which is common to all Coelographida (without any exception), and distinguishes them markedly from all the other Radiolaria, and particularly from the closely allied Coelodendrida in which we find no trace of it. The rhinocanna is a cylindrical or three-sided prismatic hollow tube, which lies in the sagittal plane, on the outer surface of each valve, arises from the base of the galea, and is directed towards the proboscis of the central capsule. The two opposite rhinocannæ open on each side of the latter (Pl. 127, figs. 4-9_m_), and usually this "nasal mouth" or the anterior opening of the nose is somewhat dilated or even funnel-shaped. The posterior opening of the nose passes directly over into the base of the cavity of the galea.

Usually the rhinocanna is densely filled up by dark phæodella, which enter by this channel into the cavity of the galea (Pl. 127, figs. 4, 5, 9). Sometimes the entire phæodium is enclosed in the two galeæ and their rhinocannæ (figs. 5, 9), whilst at other times a great part of the phæodium lies outside of their cavities, and surrounds the proboscis of the mouth, or even the anterior half of the central capsule (fig. 4). The length of the cylindrical rhinocanna is usually about equal to that of the galea, whilst the diameter of the latter is from three to five times as great as that of the former. The structure of the thin wall is the same in both. The fine reticulation (fig. 8) is produced either by true, very small and irregular pores, or by a fine network placed on the solid thin wall. We may distinguish on each rhinocanna an outer or distal convex face, which is opposite to the proximal concave face of the galea, and an inner concave or proximal face, which rests immediately upon the convex outer face of the shell-valve; a thin solid lamella of {1743}silica here completely separates the cavities of the valve and of the rhinocanna resting upon it.

The "frenula or nasal suspensoria" (Pl. 127, figs. 4-9_b_) are thin ligaments of silica, which connect the nasal mouth (_m_) with the base of the main tubes arising from the galea; they are, therefore, also common to all Coelographida, and an exclusive and marked attribute of this family. They are, however, different in the two subfamilies of this group, corresponding to the different origin of the odd or paired main tubes. In the Coeloplegmida (Pls. 126-128) from the apex of each galea arises an odd main style, the nasal style (_g_ 1), and its base is connected with the nasal mouth by an odd frenulum (_b_). In the Coelotholida however (Pl. 122) the large nasal odd style is always wanting, and there arise two paired frontal tubes from the two corners of the truncate frontal face of the galea; therefore two paired frenula are developed (a right and a left), and these, converging towards the nasal mouth, connect its distal corner with the base of the two frontal tubes.

The odd frenulum of each valve of the Coeloplegmida lies therefore in the sagittal plane, whilst the two paired frenula of the Coelotholida lie on both sides of it, to the right and left. The frenula seem to be supporting columellæ or pillars, which support the fragile skeleton, and mainly effect a fixed prop for the fragile galea. In the Coelotholida the frenula are often rather broad and irregularly fenestrated lamellæ of silica (Pl. 122, fig. 2), whilst in the Coeloplegmida they are usually thin ligaments, fenestrated only at the broadened ends, which are inserted inside on the distal apex of the nasal mouth, and outside on the base of the nasal main styles.

The large hollow tubes which arise from the galea of all Coelographida, are very variable in number, size and shape, but are always richly branched and symmetrically arranged in the dorsal and the ventral valve of the shell. They exhibit an important difference in the two subfamilies of the group; in the Coelotholida all the branches, and also the thin terminal ramules, are free, without any junction; in the Coeloplegmida, however, they communicate by frequent anastomoses, and the connected terminal ramules form on the surface of the calymma an outer lattice-mantle of very delicate network. Another marked difference between the two families is indicated by the origin and site of those main tubes which are connected with the rhinocanna by a frenulum. In the Coeloplegmida an odd, very large main tube (the nasal style) arises from the anterior apex of each galea and bears on its base an odd frenulum. This nasal style and its frenulum is altogether wanting in the Coelotholida, where two paired main tubes (the frontal tubes) arise from the lateral corners of the truncate anterior side of the galea, and are connected with the mouth of the rhinocanna by two paired convergent lateral frenula.

We distinguish in all Coelographida two different forms of hollow branched tubes, which we will call "brushes" and "styles." The brushes are dichotomously branched from the base, not verticillate; their distal ramules remain separate in the Coelotholida {1744}and compose the spiny surface, of the peculiar "fork-thicket" whilst in the Coelographida they become connected by frequent anastomoses and form the outer "lattice-mantle." The styles however are much longer projecting over the surface of the thicket or the mantle, and are not dichotomously branched, but verticillate, or armed with cruciate or alternately cruciate pairs of branches; the larger branches of the styles may be again dichotomously branched like the brushes; whilst the free prominent parts of the styles are always verticillate or cruciate-pinnate. The brushes are identical with the hollow tubes of the Coelodendrida, whilst the styles are peculiar forms of apophyses, wanting in the latter.

The minimum number of hollow tubes which arise from each valve is three, and these are probably homologous with the three primary tubes of the Coelodendrida. Two of these are paired (right and left), whilst the third is odd and lies in the sagittal plane; they have the same position as in the tripodal NASSELLARIA, and may therefore bear the same names, the two paired anterior or pectoral tubes being divergent forwards, the odd or caudal tube being bisected backwards (so in the Coelotholida, Pl. 121). The odd caudal tube (probably identical with the odd tube of the Coelodendrida) is always a brush, dichotomously branched, and never prolonged into free style. The two paired frontal or pectoral tubes, however are usually prolonged into two long verticillate styles. The basal origin also of these three primary tubes is different. The two pectoral or anterior paired tubes always arise from the galea itself whilst the posterior odd or caudal tube usually arises behind the galea from the valve (Pl. 127, figs. 4-8, _g_ 6).

Since these three primary tubes the odd caudal and the paired pectoral, are probably homologous in all Coelographida and Coelodendrida, they have a great morphological importance, similar to the three primary feet of the NASSELLARIA. All other tubes arising from the valves must be regarded as secondary apophyses, since they are not constant in all members of the two families, but present only in some of them. All the Coelotholida observed (a small number of species only) possess no secondary tubes, but only the three primary; whilst all Coeloplegmida possess one or more secondary tubes, and one of these is constant, viz., the odd nasal style, directed towards the mouth, and arising as the foremost from the apex of the galea (Pl. 127, figs. 4-8, _g_ 1).

The maximum number of tubes observed, which arise from each valve in the Coeloplegmida, is eleven; five of these are odd and placed in the sagittal plane of the body, viz.:--(A) the primary caudal tube (Pl. 127, figs. 4-8, _g_ 6); (B) an odd procaudal tube, arising between the caudal and the sagittal tube; (C) the sagittal tube, placed either in the sagittal axis of the body or near it (often prolonged into a sagittal style, Pl. 128, fig. 1); (D) an odd postnasal tube, arising between the sagittal and the nasal tube; (E) the odd nasal tube, constant in all Coeloplegmida, and connected at its base by the odd frenulum with the rhinocanna (Pl. 127, figs. 4-8, _g_ 1). All other tubes occurring in the Coeloplegmida are paired, and symmetrically arranged on both sides of the sagittal {1745}plane, at right and left; their maximum number is three pairs, viz.:--(F) the paired pectoral tubes (as the foremost), directed forwards; (G) the paired frontal or lateral tubes, placed either in the frontal axis of the valve, or in a neighbouring axis, directed towards the right and left pole (Pl. 127, figs. 4-8, _g_ 4 and _g_ 5); (H) the paired tergal tubes, directed backwards (constant in all Coeloplegmida). The origin of these tubes is rather variable, since they arise in nearly allied species, sometimes independently of one another, at other times united at the base. But a closer comparison of them in the different species will demonstrate their homology, caused by constant heredity.

The terminal ramules of the brushes, which form the subspherical "fork-thicket" in the Coelotholida, the outer "lattice-mantle" in the Coeloplegmida, are constantly armed at the distal ends either with spathillæ or with anchor-pencils, bunches of those most elegant spinulate threads, which bear at the free end an anchor, or a whorl of two, three, or four recurved teeth (Pl. 122, fig. 8; Pl. 127, fig. 10; Pl. 128, figs. 1, 6). The pencils are usually dichotomously branched, their threads zig-zag or delicately serrate, often armed with very small recurved denticles, and the anchor teeth (commonly three or four) are usually smooth on the convex outer, serrate on the concave inner edge. The entire surface of the subspherical thicket in the Coelotholida, and of the polyhedral lattice-mantle in the Coeloplegmida, is armed with thousands of those most elegant spathillæ, or anchor-pencils.

The "fork-thicket" of the Coelotholida is identical with that of the Coelodendrida, and is composed only of the innumerable dichotomous branches of the hollow tubes. It envelops the two central valves and the enclosed central capsule in the same way as in the Coelodendrida. But the Coelotholida differ from these latter in constantly possessing a rhinocanna and two frenulæ. The entire form of this thicket, which in the few species observed was never complete, but always more or less destroyed, is usually probably subspherical or polyhedral, sometimes cordate or kidney-shaped. Its surface is densely studded with thousands of spathillæ. Its diameter is about four to eight times as great as that of the enclosed bivalve shell.

The "lattice-mantle" of the Coeloplegmida, which replaces in this subfamily the fork-thicket of the Coelotholida, is always produced by the anastomoses of the distal ramules of the brushes, and of those branches of the styles which do not proceed over the surface of the mantle. Its network is always very irregular, and composed of polygonal meshes of very different sizes. Usually it is quite simple, and may be compared with the cortical shell of the Disphærida. More rarely it is more or less spongy. Its surface is densely studded with thousands of spathillæ or anchor-pencils. The entire form of the lattice-mantle is always symmetrically polyhedral, since its dorsal and ventral halves are symmetrically developed on both sides of the equatorial plane, and therefore correspond perfectly to the enclosed smaller halves of the central bivalve shell. The two valves of the lattice-mantle (dorsal and ventral valves) are never really united and grown together, {1746}but are in loose contact in the equatorial plane; here the free edges of both valves catch into one another by means of free ramules (Pl. 128, figs. 1, 7). This loose connection is similar to what occurs in the Conchopsida (or in the Concharida with dentate edges), but never so regular. The special form of the polyhedral lattice-mantle depends on the number, arrangement, and development of the styles, which proceed over its surface; it preserves the polyhedral form of the calymma, on the surface of which it is deposed.

The characteristic styles of the Coelographida (which are never found in the preceding Coelodendrida) are longer hollow tubes, symmetrically disposed on both valves. They are prominent over the surface of the fork-thicket in the Coelotholida, of the lattice-mantle in the Coeloplegmida. They bear in these latter a peculiar terminal coronet on their distal end, whilst in the former this end is armed with large pencils of spathillæ. The styles may be forked once or twice at their base, but in their greatest part they are verticillate, and not dichotomously branched like the brushes. The lateral branches of the styles are usually very numerous and regularly cruciate in alternating opposite pairs. In the odd nasal style, _e.g._, the first and third pairs of opposite lateral branches usually lie in the frontal plane, the second and fourth in the sagittal plane, perpendicular to the former, and so on. A similar regular disposition of the lateral branches is found also in other styles, but not in all. There are certain styles in which the lateral branches are not opposite in pairs, but alternate or verticillate, and others in which they represent unequal branches of forks, so that each single segment of the branched style represents the stouter branch of a fork, and the appertaining lateral branch the thinner branch of the fork. Further accurate examinations are required to recognise the different laws of the ramification of the styles in the different forms of Coelographida. The lateral branches of the styles are usually again dichotomously branched inside the lattice-mantle, and their distal ends pass over into its network. But the verticillate or cruciate branches, which arise from the free part of the styles outside the lattice-mantle, are always armed with the same elegant pencils of spathillæ which cover the surface of the fork-thicket in the Coelotholida, the surface of the lattice-mantle in the Coeloplegmida. These pencils also are often regularly opposite in pairs, and the pairs alternate in two planes perpendicular one to another (Pl. 128, figs. 1, 4).

The terminal coronets are peculiar ornaments which protect the distal ends of the styles in the Coeloplegmida, whilst in the Coelotholida these are armed with the usual pencils of spathillæ (Pl. 122, fig. 8). Each coronet is usually produced by the double, triple, or quadruple furcation of the free distal end of the style; therefore composed of four, eight, or sixteen terminal branches, which, on account of their peculiar form and function, we may call "fingers." More rarely the ramification of the coronets is more or less irregular, and sometimes the number of the fingers exceeds twenty or even thirty.

In the majority of species eight fingers are regularly disposed (Pl. 127, figs. 1-3; Pl. 128, figs. 1-8). Often too sixteen occur, rarely four only. Sometimes the fingers {1747}are placed nearly in one plane and form a hand. The form of the fingers is very variable and most characteristic of the individual species. Very often they have the shape of a human finger, and are smooth, spinulate, or armed with recurved hooks. The distal end of each finger often again bears a small coronet or a spathilla (Pl. 128, figs. 5-9), and sometimes it is arrow-shaped (Pl. 126, fig. 2_a_). All these apophyses of the terminal coronets as well as the anchor-pencils of the mantle and the finest branches of the tubes, are hollow and filled up by jelly.

The different number and arrangement of the styles offers the best means for the distinction of genera in the Coelographida. The minimum number is six (_Coelographis_, Pl. 126, fig. 1), the maximum number sixteen (_Coelothamnus_, Pl. 122, fig. 3, and _Coelagalma_, Pl. 126, fig. 4). Since the arrangement of the styles in both valves is constantly symmetrical, the fundamental form of the whole body is in all Coeloplegmida "amphithect," as in the _Ctenophora_. The longitudinal or main axis of the body is vertical, with two distinct poles; the proboscis of the central capsule and the two rhinocannæ are directed upwards, towards the oral pole; the caudal tube of each valve is directed downwards, towards the aboral pole. The two other axes of the body are unequal, horizontal, and perpendicular one to the other; each has two equal poles. On the poles of the sagittal axis lie the galeæ of the dorsal and ventral valves; on the poles of the frontal axis lie the two secondary openings or parapylae of the central capsule. The frontal fissure or the large cleft between the dorsal and ventral valves of the skeleton lies in the vertical frontal plane of the body, which is perpendicular to the vertical sagittal plane; the equatorial plane, however, is horizontal.

The _central capsule_ of the Coelographida exhibits the same shape and position as in the preceding Coelodendrida. It is subspherical, slightly depressed in the direction of the main axis, and lies enclosed between the two central valves of the lattice-shell. Its three constant openings lie in the frontal plane, and therefore in the frontal fissure between the two valves. The astropyle, or the main-opening of the capsule, lies on the oral pole of the main axis, and its radiate operculum (_d_) is directed upwards; the curved proboscis arising from it (_o_) is prominent between the mouths of the two opposed rhinocannæ. The two lateral parapylæ or accessory openings lie on both sides of the aboral pole, on the right and left (Pl. 127, figs. 4-6). The large spheroidal or somewhat lenticular nucleus (_n_) is usually about half as broad as the capsule, and contains numerous nucleoli. The protoplasm around the nucleus contains many vacuoles, and in the oral part of the capsule (between nucleus and operculum) often numerous groups of crystals (Pl. 127, figs. 4-6_k_, 7). The double membrane of the central capsule exhibits the same shape as in the other PHÆODARIA.

The calymma, or the extracapsular jelly-veil, is in the Coelographida very voluminous, and includes the entire skeleton, the fork-thicket of the Coelotholida, the lattice-mantle of the Coeloplegmida, and also the prominent large styles. Only the distal ends of the {1748}latter (with the terminal coronets), and the anchor pencils, covering the surface of the thicket and the mantle, seem to project over the surface of the calymma. The entire form of the latter is therefore a symmetrical polyhedron. The phæodium fills up a small part only of the calymma, and is usually enclosed in the two galeæ and their rhinocannæ (Pl. 127, figs. 5, 9), but often also a part of the phæodium is scattered around the oral half of the central capsule.

_Synopsis of the Genera of Coelographida._

------------------------------------------------------------------------- I. Subfamily Coelotholida. Rhinocanna of each valve with two paired lateral frenula. The distal ends of the dichotomous brushes are not united by anastomoses, and form an outer bivalved fork-thicket. ------------------------------------------------------------------------- Eight paired styles (four on each valve), 731. _Coelotholus_.

Twelve paired styles (six on each valve), 732. _Coelothauma_.

Sixteen paired styles (eight on each valve), 733. _Coelothamnus_. ------------------------------------------------------------------------- II. Subfamily Coeloplegmida. Rhinocanna of each valve with an odd sagittal frenulum. The distal ends of the dichotomous brushes are united by anastomoses, and form an outer bivalved lattice-mantle. ------------------------------------------------------------------------- Mantle with six styles. { One odd and two paired { styles on each valve, 734. _Coelographis_.

Mantle with eight styles. { Two odd and two paired { styles on each valve, 735. _Coelospathis_.

Mantle with ten styles. { One odd and four paired { styles on each valve, 736. _Coelodecas_.

Mantle with twelve { Two odd and four paired styles. { styles on each valve, 737. _Coelostylus_.

Mantle with fourteen { One odd and six paired styles. { styles on each valve, 738. _Coeloplegma_.

Mantle with sixteen { Two odd and six paired styles. { styles on each valve, 739. _Coelagalma_.

Subfamily 1. COELOTHOLIDA, Haeckel.

_Definition._--#Coelographida# with two paired lateral frenula on each galea, and with free terminal branches on the hollow radial tubes, without an external lattice-mantle. Eight to sixteen long styles are prominent over the surface of the fork-thicket, which is composed of the caudal brush and the dichotomous basal branches of the styles.

Genus 731. _Coelotholus_,[347] n. gen.

_Definition._--#Coelographida# with two paired lateral frenula on each galea, without external lattice-mantle, armed with eight styles (two pairs of styles on each valve).

{1749}The genus _Coelotholus_ and the two following genera form together the subfamily Coelotholida, the hollow tubes of which do not communicate by anastomosing branches, and therefore form no lattice-mantle, as in the following subfamily Coeloplegmida. Another important difference between these two subfamilies of Coelographida is found in the arrangement of the main tubes and their connection with the rhinocanna. In all Coelotholida a pair of divergent frontal styles arise from the truncate oral side of each galea, and are connected with the mouth of the rhinocanna by two lateral convergent paired frenula (right and left); whereas the characteristic odd nasal style, which in all Coeloplegmida arises from the sagittal apex of each galea and is connected with the mouth of the rhinocanna by an odd sagittal frenulum, is always wanting. The total number of long verticillate styles, which project over the outer surface of the fork-thicket, is eight in _Coelotholus_, whilst it is twelve in _Coelothauma_, and sixteen in _Coelothamnus_. The two latter may be derived from _Coelotholus_, as the common ancestral genus of this subfamily.

1. _Coelotholus octonus_, n. sp. (Pl. 122, figs. 1, 2).

Eight styles of equal length, regularly zig zag, twice as long (in their free part) as the diameter of the loose fork-thicket. Anchor-pencils gradually tapering from the proximal towards the distal end. Each of the four primary frontal tubes (to the right and left of each valve) is simply forked, and the pectoral (anterior) branch of each tube is so diametrically opposed to the tergal (posterior) tube of the other side, that they form together a double cross.

_Dimensions._--Diameter of the whole body 12, of the fork-thicket 2.5.

_Habitat._--South-Eastern Pacific, Station 300, depth 1375 fathoms.

2. _Coelotholus cruciatus_, n. sp.

Eight styles of equal length, straight, twice as long (in their free part) as the diameter of the dense fork-thicket. Anchor-pencils of about equal size throughout their whole length. Each of four primary frontal tubes is divided into two equal, widely divergent branches; the anterior branches of the right side are diametrically opposed to the posterior branches of the left side, so that all eight together form a double cross.

_Dimensions._--Diameter of the whole body 20, of the fork-thicket 4.0.

_Habitat._--South-Western Pacific (off Sydney), Station 164A, depth 1200 fathoms.

3. _Coelotholus ancoratus_, n. sp.

Eight styles of different lengths, slightly curved. Anchor-pencils gradually tapering from the proximal to the distal end. Each of the four primary frontal tubes is divided into two divergent {1750}branches of different lengths; the anterior (or pectoral branch) twice as long (in the free part) as the diameter of the fork-thicket, the posterior (or tergal branch) three times as long.

_Dimensions._--Diameter of the whole body 20, of the fork-thicket 3.2.

_Habitat._--Indian Ocean (Sunda Strait), Rabbe, surface.

Genus 732. _Coelothauma_,[348] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Coelographida# with two paired lateral frenula on each galea, without external lattice-mantle, armed with twelve styles (three pairs of styles on each valve).

The genus _Coelothauma_ differs from the preceding _Coelotholus_, its ancestral form, in the possession of twelve long, prominent styles, six of which are opposite in three pairs on each valve. In the single species observed each of the four main tubes (opposite in pairs on the frontal corners of the two galeæ) is simply forked, as in _Coelotholus_; but whilst in this latter all eight styles remain simple, in _Coelothauma_ the anterior (or pectoral) branch only is simple, the posterior (or tergal) branch is again forked.

1. _Coelothauma duodenum_., n. sp. (Pl. 122, figs. 3-5).

Twelve styles straight, of different lengths. Two short bilateral main tubes arise opposite in pairs from the two frontal corners of each galea, and are divided into an anterior and posterior branch. The anterior or pectoral branch is simple, and twice as long as the diameter of the fork-thicket. The posterior or tergal branch is again forked near the base, and its two divergent branches are three times as long as the diameter of the fork-thicket. All twelve styles are densely studded with anchor-pencils of nearly equal size.

_Dimensions._--Diameter of the whole body 21, of the fork thicket 3.5.

_Habitat._--South-Western Pacific (east of New Zealand), Station 169, depth 700 fathoms.

Genus 733. _Coelothamnus_,[349] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Coelographida# with two paired lateral frenula on each galea, without external lattice-mantle, armed with sixteen styles (four pairs of styles on each valve).

The genus #Coelothamnus# differs from its ancestral form, _Coelotholus_, in the duplication of the number of long verticillate styles, which are prominent over the surface of the {1751}dense fork-thicket. Whilst in _Coelotholus_ each frontal main tube (arising from the frontal corner of the galea at right and left) is divided into an anterior or pectoral, and a posterior or tergal style, in _Coelothamnus_ each of these two divergent main styles is again forked, so that the total number of projecting and radially diverging styles amounts to sixteen. One Mediterranean species of this genus, _Coelothamnus davidoffii_, has been already described by Bütschli in 1882 (Zeitschr. f. wiss. Zool., vol. xxxvi. p. 486, Taf. xxxi.). Though its description on the whole is accurate, some important errors, which may be here corrected, are to be met with. The two central valves of the lattice-shell (dorsal and ventral) are symmetrically equal in size and in form, as in all other Coelographida; the different forms and the inverse arrangement of the two valves, described by Bütschli (pp. 488, 491), were effected by an artificial dislocation and inversion. The peculiar opening [alpha], which, according to his opinion, was supposed to bring about a direct communication between the cavities of the galea and its valve, is in reality the optical section of the rhinocanna, the two convergent frenula of which ([gamma]) he figured, but did not recognise. _Coelothamnus_ attains the greatest size among all Radiolaria; the diameter of the body in _Coelothamnus maximus_ amounts to 33 mm.

1. _Coelothamnus bivalvis_, n. sp. (Pl. 122, figs. 6-9).

Sixteen styles all of equal length, about three times as long (in their free part) as the diameter of the dense fork-thicket. The size of the anchor-pencils tapers from the proximal to the distal end. Each of the four primary frontal tubes (which arise in opposite pairs from the frontal corners of the two galeæ) is twice forked, and so produces four styles.

_Dimensions._--Diameter of the whole body 18, of the fork-thicket 2.4 to 3.0.

_Habitat._--North Atlantic, Canary Islands, Station 354, surface.

2. _Coelothamnus davidoffii_, Bütschli.

_Coelothamnus davidoffii_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 486, Taf. xxxi.

Sixteen styles all of equal length (?), about four times as long (in their free part) as the diameter of the fork-thicket. The size of the anchor-pencils is nearly equal throughout their entire length. (Compare the careful description of this species by Bütschli.)

_Dimensions._--Diameter of the whole body 15, of the fork-thicket 1.8.

_Habitat._--Mediterranean (Villafranca, near Nice), Davidoff, surface.

3. _Coelothamnus sedecimalis_, n. sp.

Sixteen styles straight, of different sizes. The pectoral or anterior branch of each frontal main tube is simple, and twice as long as the diameter of the large fork-thicket. The tergal or posterior branch is forked at the base, and its anterior branch is again forked in the middle part, so that three {1752}long divergent styles arise from each tergal tube. The hindermost of these is the longest, three times as long as the diameter of the fork-thicket. All anchor-pencils have nearly equal size.

_Dimensions._--Diameter of the whole body 22, of the fork-thicket 5.2.

_Habitat._--South Pacific, Station 166 (west of New Zealand), depth 275 fathoms.

4. _Coelothamnus maximus_, n. sp.

Sixteen styles straight, of different sizes. The four frontal main tubes are already forked at the base, so that from each frontal corner of the two galeæ two divergent tubes, an anterior or pectoral and a posterior or tergal, arise. Each of these is again forked, and each branch prolonged into a very long verticillate style. The hindermost style of each side is the longest, twice as long as the foremost, and one and a half times as long as the two intermediate styles. The size of the anchor-pencils decreases in the distal third of the styles.

_Dimensions._--Diameter of the whole body 32, of the fork-thicket 7.5.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

Subfamily 2. COELOPLEGMIDA, Haeckel.

_Definition._--#Coelographida# with an odd sagittal frenulum on each galea, and with an external bivalved lattice-mantle, produced by the anastomosing branches of the hollow radial tubes. Six to sixteen long styles are prominent over the surface of the mantle, and bear terminal coronets.

Genus 734. _Coelographis_,[350] n. gen.

_Definition._--#Coelographida# with an odd sagittal frenulum on each galea and an outer lattice-mantle, armed with six styles (one odd and two paired styles on each valve).

The genus _Coelographis_ is the simplest form of the Coeloplegmida, or of those Coelographida in which the branches of the arborescent tubes are united on the surface of the calymma, and form a delicate bivalved lattice-mantle. In all these Coeloplegmida an odd nasal main style is developed on the apex of the galea, and this is connected by an odd sagittal frenulum with the mouth of the rhinocanna, _Coelographis_ differs from the other Coelographida in the minimum number of coronal styles, viz., three on each valve, an odd anterior (nasal) and two paired posterior (tergal).

1. _Coelographis regina_, n. sp. (Pl. 126, figs. 1_a_-1_c_).

Shell-mantle twice as long as broad, its frontal perimeter isosceles triangular, with a triangular excision at the base, its sagittal perimeter slenderly ovate. Nasal odd style twice as long as the {1753}paired tergal styles, the former with ten to twelve, the latter with five to six alternate-cruciate pairs of lateral branches. Terminal coronets (on the free distal ends of the styles) palmate, with ten to twelve spinulate, irregular, finger-shaped branches (fig. 1_d_).

_Dimensions._--Length of the shell 5.6, breadth 2.7.

_Habitat._--South-Eastern Pacific (off Juan Fernandez), Station 297, depth 1775 fathoms.

2. _Coelographis sagittella_, n. sp.

Shell-mantle one and a half times as long as broad, its frontal perimeter arrow-shaped, isosceles triangular, with a deep concave excision at the base, its sagittal perimeter slenderly ovate. Nasal odd style one and a half times as long as the paired tergal styles, the former with fourteen to sixteen, the latter with eight to nine verticils of branches. Terminal coronets three times forked, with eight subregular, broad and spinulate, finger-shaped branches.

_Dimensions._--Length of the shell 6.4, breadth 4.2.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

3. _Coelographis hexastyla_, n. sp.

Shell-mantle one and a half times as long as broad, very similar to the preceding species, its frontal perimeter isosceles triangular, with a flat basal excision. Nasal odd style one and a third times as long as the paired tergal styles, the former with fourteen to sixteen, the latter with ten to twelve verticils of branches. Terminal coronets with four forks in the form of a cross, and eight divergent spinulate fingers.

_Dimensions._--Length of the shell 4.2, breadth 3.1.

_Habitat._--North Pacific, Station 259, depth 2225 fathoms.

4. _Coelographis gracillima_, Haeckel.

_Coelodendrum gracillimum_ (_partim_) Haeckel, 1862, Monogr. d. Radiol., Taf. xxxii. figs. 2, 3.

Shell-mantle one and a third times as long as broad, similar to the three preceding species, its frontal perimeter isosceles triangular. Nasal odd style one and a half times as long as the two paired tergal styles, the former with eleven or twelve, the latter with seven or eight pairs of branches. Terminal coronets irregularly dichotomously branched, with twelve to sixteen spinulate fingers. The network of the mantle is also spinulate (_loc. cit._, fig. 3). This species was formerly confounded by me with _Coelodendrum gracillimum_ (_loc. cit._, fig. 1), since I found a fragment only of the former entangled in the branch-work of the latter (1859, in Messina). Afterwards (in 1877) I observed a complete specimen in Corfu.

_Dimensions._--Length of the shell 3.2, breadth 2.4.

_Habitat._--Mediterranean (Messina, Corfu), surface.

5. _Coelographis triangulum_, n. sp.

Shell-mantle about as long as broad, its frontal perimeter equilateral triangular, without basal excision, with three equal straight sides. Nasal odd style and the two paired pectoral styles nearly {1754}of equal length, each with ten to twelve alternate-cruciate pairs of lateral branches. Terminal coronets umbrella-shaped, composed of eight equal, simply forked branches.

_Dimensions._--Length of the shell 3.6, breadth 3.4.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

Genus 735. _Coelospathis_,[351] n. gen.

_Definition._--#Coelographida# with an odd sagittal frenulum on each galea and an outer lattice-mantle, armed with eight styles (two odd and two paired styles on each valve).

The genus _Coelospathis_ differs from the preceding _Coelographis_ in the possession of four coronal styles on each valve. Two of these are odd and lie in the sagittal plane, viz., the constant vertical nasal style (directed towards the mouth), and the horizontal sagittal style, which is placed in the equatorial plane, in the sagittal axis of the body. The two other styles are paired and identical with the tergal styles of _Coelographis_, directed backwards, and divergent to right and left.

1. _Coelospathis ancorata_, n. sp. (Pl. 128, figs. 1-7).

Shell-mantle one and a half times as long as broad, its frontal perimeter isosceles triangular; its zonal perimeter square, its sagittal perimeter nearly rectangular, with a concave excision on the oral side (fig. 1). Odd nasal styles of both valves divergent in the sagittal plane (each with fourteen to sixteen pairs of branches), three times as long as the odd sagittal styles (each with three or four pairs) and twice as long as the paired tergal styles (each with four to six pairs of branches). Terminal coronets (on the free distal end of the styles) three times forked, each with eight slender, widely divergent fingers, which are curved, zig-zag, and armed with alternating recurved hooks; at the end of each finger a verticil of four to six small recurved teeth (fig. 5).

_Dimensions._--Length of the shell 2 to 3, breadth 1.2 to 2.1.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

2. _Coelospathis octostyla_, n. sp. (Pl. 128, fig. 8).

Shell-mantle one and a third times as long as broad, very similar to the preceding species; but differing from this in the following characters: the odd nasal styles bear ten to twelve pairs of branches, and are twice as long as the odd sagittal and the paired pectoral styles, which are nearly equal in size (each with five or six pairs of branches). The eight fingers of the terminal coronets are less divergent and curved than in the preceding species, and each finger bears at its end a verticil of four to six divergent, slender teeth, which are not recurved (fig. 8).

_Dimensions._--Length of the shell 2.2 to 2.6, breadth 1.7 to 1.9.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

{1755}3. _Coelospathis octodactyla_, n. sp. (Pl. 128, fig. 9).

Shell-mantle about as long as broad, in the frontal perimeter nearly isosceles triangular, very similar to the two preceding species; it differs from them in the following characters: all eight styles have nearly equal size, and each bears six to eight pairs of branches. The eight fingers of the terminal coronets diverge nearly in one plane, and are not curved in a zigzag manner, but armed with alternate, slender, recurved hooks, which are larger than in the two preceding species, and geniculate at the base; the distal end of each finger bears a verticil of eight to ten very small divergent teeth, which are not recurved (fig. 9).

_Dimensions._--Length of the shell 2.4, breadth 2.2.

_Habitat._--North Pacific, Station 252, surface.

Genus 736. _Coelodecas_,[352] n. gen.

_Definition._--#Coelographida# with an odd sagittal frenulum on each galea and an outer lattice-mantle, armed with ten styles (one odd and four paired styles on each valve).

The genus _Coelodecas_ is closely allied to _Coelographis_, but differs from it in the development of a new pair of styles on each valve. These are placed between the odd nasal and the paired tergal styles, are usually directed laterally, parallel to the frontal axis of the body, and may therefore be called frontal or lateral styles. The total number of coronal styles is therefore ten.

1. _Coelodecas sagittaria_, n. sp. (Pl. 126, figs. 2_a_, 2_b_).

Shell-mantle one and a half times as long as broad; its frontal perimeter pentagonal, with a deep median incision at the base; the two oral sides of the pentagon twice as long as the two lateral sides, and one and a half times as long as the base. Sagittal perimeter ovate; equatorial perimeter subcircular. Nasal odd style of each valve with fourteen to sixteen pairs of branches, one and a half times as long as the paired frontal styles (each with eight to nine pairs), and twice as long as the paired tergal styles (each with four to six pairs of branches). Terminal coronets (on the free distal ends of the styles) richly branched, each with thirty to forty thorny fingers, which bear a conical point with recurved teeth, like an arrow.

_Dimensions._--Length of the shell 3.2, breadth 2.1.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

2. _Coelodecas decastyla_, n. sp.

Shell-mantle one and a third times as long as broad; its frontal perimeter pentagonal, with a slight incision on the base; the two oral sides of the pentagon as long as the base, and one and a {1756}half times as long as the two lateral sides. Nasal odd style of each valve with ten to twelve pairs of branches, about twice as long as the four paired frontal and tergal styles, each of which bears five or six pairs. Terminal coronets three times forked, each with eight straight, spinulate, slightly divergent fingers, shaped like a human finger.

_Dimensions._--Length of the shell 3.6, breadth 2.7.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.

3. _Coelodecas pentagona_, n. sp.

Shell-mantle about as long as broad; its frontal perimeter nearly regular pentagonal, with five equal sides. Nasal odd style of each valve with six to eight pairs of branches scarcely longer than the four paired frontal and tergal styles, each of which is provided with four to six pairs. Terminal coronets irregularly branched, each with twelve to sixteen slender curved fingers, which bear at the distal end a spinulate knob.

_Dimensions._--Length of the shell 2.6, breadth 2.4.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

Genus 737. _Coelostylus_,[353] n. gen.

_Definition._--#Coelographida# with an odd sagittal frenulum on each galea and an outer lattice-mantle, armed with twelve styles (two odd and four paired styles on each valve).

The genus _Coelostylus_ is characterised by the possession of twelve coronal styles; it is closely allied to _Coelospathis_, and differs from this in the development of a new pair of styles on each valve. These are placed between the odd nasal and the odd sagittal style of each valve, they are directed forwards, and may therefore be called "pectoral styles."

1. _Coelostylus bisenarius_, n. sp. (Pl. 126, fig. 3_a_, 3_b_).

Shell-mantle one and a third times as long as broad; its frontal perimeter pentagonal, with a deep median incision at the base; the two oral sides of the pentagon about as long as the basal odd side, and half as long as the two lateral sides. Sagittal perimeter (fig. 3_a_) octagonal; the three paired lateral sides of the bilateral octagon about equal, and somewhat shorter than the basal and oral odd sides. Equatorial perimeter rounded square. Nasal odd style of each valve with twelve alternate-cruciate pairs of lateral branches, about twice as long as the two paired pectoral styles (each with four pairs), and the odd sagittal style (with six pairs); the two paired tergal styles bear eight pairs and are longer than the latter, shorter than the nasal style. All styles are more or less curved, divergent, and at the distal end four times forked, bearing a terminal coronet with sixteen spinulate fingers (fig. 3_b_).

_Dimensions._--Length of the shell 4.2, breadth 3.2.

_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.

{1757}2. _Coelostylus flabellatus_, n. sp.

Shell-mantle one and a half times as long as broad, very similar to that of the preceding species. It differs from this mainly in the peculiar form of the twenty-four terminal coronets, which are flabellate and very similar to the terminal branches of _Coelodendrum flabellatum_ (Pl. 121, figs. 5, 6). I formerly supposed, therefore, that both forms belonged to one and the same species. But though I had no complete specimens of the two species, I was afterwards led to the opinion that one and the same peculiar form of terminal branches is here produced by adaptation to similar conditions in two very different genera. Each coronet is a flat flabellum, placed in a meridian plane, and composed of eight pairs of spinulate branches as figured, _loc. cit._, in figs. 5 and 6. The cap-shaped distal end of each finger is armed with eight to twelve recurved teeth.

_Dimensions._--Length of the shell 3.8, breadth 2.6.

_Habitat._--North Pacific, Station 252, surface.

Genus 738. _Coeloplegma_,[354] n. gen.

_Definition._--#Coelographida# with an odd frenulum on each galea and an outer lattice-mantle, armed with fourteen styles (one odd and six paired styles on each valve).

The genus _Coeloplegma_, distinguished by the possession of fourteen coronal styles, is closely allied to _Coelodecas_, but differs from it in the development of a new pair of styles on each valve. These are placed between the odd nasal and the paired frontal styles, are directed forwards, and may therefore be called pectoral styles, corresponding to those of _Coelostylus_.

1. _Coeloplegma murrayanum_, n. sp. (Pl. 127, figs. 1-13.).

Shell-mantle about as long as broad, its frontal perimeter subcircular, or slightly pentagonal, with five convex sides, its sagittal perimeter also nearly circular. Odd nasal style with six to eight, the paired pectoral styles with two or three, lateral styles with three to five, and tergal styles with six to nine pairs of branches. The central capsule constantly contains masses of crystals (figs. 4-7). Terminal coronets (on the free distal ends of the styles) three times furcate, each with eight simple and short fingers. This interesting species, discovered by Dr. John Murray in August 1882, during the expedition of H.M.S. "Triton," in great numbers in the Gulf Stream, off the Færöe Channel, is very variable and connected by numerous transitional forms with the following closely allied species. (Compare the following note.)

_Dimensions._--Length of the shell 1.6 to 2.2, breadth 1.5 to 2.1.

_Habitat._--North Atlantic, Gulf Stream, off the Færöe Channel, in depths between 40 and 200 fathoms, John Murray.

{1758}2. _Coeloplegma tritonis_, n. sp. (Pl. 127, figs. 2-13).

Shell-mantle one and a quarter times as long as broad, its frontal perimeter heptagonal, with seven concave sides (fig. 2), its sagittal perimeter ovate, its zonal perimeter nearly square (fig. 3). Odd nasal style with twelve to fourteen, the paired pectoral styles with three to four, lateral styles with six to eight, and tergal styles with eight to ten pairs of branches. Coronets three times forked, each with eight terminal branches, bearing a small spinulate knob. This remarkable species, in external appearance very different from the preceding, is connected immediately with it by numerous transitional varieties; both species represent the opposite terminal poles of a long series of "Darwinian metamorphic forms." If only the two specimens, figured in Pl. 127, figs. 1 and 2, were known, every one would distinguish them as two widely different species. But the careful comparison of numerous intermediate forms demonstrates that there is no "missing link" in this long and remarkable chain. The careful comparative study of these very variable and most highly developed Coelographida may be regarded as a strong argument for the theory of descent, and explains the true "origin of species."

_Dimensions._--Length of the shell 1.8 to 2.5, breadth 1.5 to 2.1.

_Habitat._--North Atlantic, Gulf Stream, off the Færöe Channel, in depths between 40 and 200 fathoms, John Murray.

3. _Coeloplegma tetradecastylum_, n. sp.

Shell-mantle one and a third times as long as broad, its frontal perimeter heptagonal, with seven concave sides. Similar to the preceding species, differs from it mainly in the prolonged nasal style, which bears sixteen to eighteen pairs of branches, and is about three times as long as each of the six paired styles, each of which bears five to six pairs of branches. Coronets three times forked, each with eight terminal branches, armed with scattered spines, and bearing a knob with three recurved hooks.

_Dimensions._--Length of the shell 3.2, breadth 2.4.

_Habitat._--Tropical Atlantic, Stations 335 to 342, surface.

4. _Coeloplegma atlanticum_, n. sp.

Shell-mantle one and a half times as long as broad, its frontal perimeter ovate. Similar to _Coeloplegma murrayanum_ (Pl. 127, fig. 1), differs from it in the different length of the styles; the nasal odd style (with eighteen to twenty pairs of branches) is about twice as long as the lateral styles (with ten to twelve pairs), and three times as long as the pectoral and tergal styles (with six to eight pairs). Coronets four times forked, each with sixteen terminal branches, armed with recurved spines, and bearing a cross of four curved hooks.

_Dimensions._--Length of the shell 2.5, breadth 1.7.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

{1759}Genus 739. _Coelagalma_,[355] n. gen.

_Definition._--#Coelographida# with an odd sagittal frenulum on each galea and an outer lattice-mantle, armed with sixteen styles (two odd and six paired styles on each valve).

The genus _Coelagalma_ represents the highest degree of development among the Coelographida, and exhibits the maximum number of coronal styles in this family, viz., sixteen (eight on each valve). Two of these are odd (as in _Coelospathis_ and _Coelostylus_), viz., the longitudinal anterior nasal style, and the horizontal sagittal style. The six others are paired (as in _Coeloplegma_), viz., two anterior or pectoral, two lateral or frontal, and two posterior or tergal styles. Since _Coelagalma_ in this highest developed armature exceeds all the other Coeloplegmida, and exhibits at the same time the utmost complexity in structural detail, it may be regarded as one of the most perfect forms not among the PHÆODARIA only, but among all Radiolaria.

1. _Coelagalma mirabile_, n. sp. (Pl. 126, figs. 4, 4_a_).

Shell-mantle one and a half times as long as broad, its frontal perimeter (fig. 4_a_) heptagonal, with seven concave sides, its sagittal perimeter octagonal, its equatorial perimeter hexagonal (fig. 4_b_), the corners of the polygons are marked by the sixteen prominent styles. Nasal odd style longer; and sagittal odd style shorter, than the six paired styles of each valve; the two pectoral styles are directed forwards, the two lateral styles are nearly opposed in the horizontal frontal diameter, while the two shorter tergal styles are directed backwards. The terminal coronets (at the distal ends of the sixteen styles) are four times forked, with sixteen equal spinulate fingers, each finger at the distal end with eight recurved teeth. The entire surface of the bivalved latticed mantle is densely studded with hundreds of most elegant anchor-pencils, so that the external appearance of this beautiful species becomes one of the most wonderful among Radiolaria.

_Dimensions._--Length of the shell 5.4, breadth 3.6.

_Habitat._--Central area of the Pacific, Station 271, depth 2425 fathoms.

{1760}NOTE ON THE DIMENSIONS AND MEASUREMENTS OF THE DESCRIBED SPECIES OF RADIOLARIA.

All the dimensions of the species of Radiolaria described in the present work are given in millimetres. In the majority of the species the dimensions of only a single observed specimen have been measured by the micrometer, and usually only the most important proportions have been recorded. But since the outlines of nearly all the species figured (with very few exceptions) have been drawn by the camera lucida, and therefore usually are almost perfectly exact, and since the excellent artist, Mr. Adolph Giltsch, has executed the lithographic plates with the greatest accuracy, having examined the objects themselves under the microscope, it is very easy to determine the dimensions of all the separate parts by comparative measurement. In very many of the species described (perhaps nine hundred or a thousand) several specimens of each species (usually three or four) have been measured comparatively, and the dimensions recorded are taken as averages. A very important contribution to the general conception of the proportions, and especially to the important question of the constancy of the dimensions, has been given by my honoured friend Dr. Reinhold Teuscher of Jena. This excellent observer, to whom I am indebted for much and important co-operation in my Radiolarian work, has instituted at my request a long series of measurements, with the view of comparing the dimensions (of the entire skeleton as well as of its individual parts) in numerous (usually twenty or thirty) specimens of one and the same species. About three hundred species of very different groups (mainly #Sphæroidea#, #Discoidea#, #Spyroidea#, and #Cyrtoidea#) have been measured in this manner, and the general survey of the results obtained (about eight thousand measurements were recorded) has enabled me to form a good opinion of the constancy and variability of the dimensions in the individual species. The general result is, that they are not absolutely constant in any given case, but that each species (of which many specimens have been carefully compared) exhibits a certain degree of variability in all its proportions. The general meaning of "species," therefore, is in the unicellular Radiolaria the same as in all other organisms, and its development follows the same laws as are so accurately explained by Charles Darwin in his Origin of Species.

ADDENDA.

I. _List of Twenty-two Deep-Sea Radiolarians from the Banda Sea._

P. Harting (L. N. 18) published in 1863 the description of 14 SPUMELLARIA and 8 NASSELLARIA, taken in depths between 900 and 4000 fathoms, in the Banda Sea. The figures of them are, however, for the most part not complete enough. The names are the following:--

I. SPUMELLARIA.

1. _Haliomma nitidum_, figs. 13, 14 = _Heliodiscus_? 2. _Haliomma gracile_, fig. 15 = _Acanthosphæra_? 3. _Haliomma lens_, fig. 16 = _Stylodiscus_? 4. _Haliomma pyriforme_, fig. 17 = _Cenellipsis_? 5. _Haliomma scutum_, fig. 18 = _Botryocella_? 6. _Haliomma polyacanthum_, fig. 40 = _Druppocarpus_? 7. _Haliomma inerme_, fig. 41 = _Thecosphæra_? 8. _Haliomma oblongum_, fig. 42 = _Druppula_? 9. _Haliomma amphiaspis_, fig. 43 = _Monozonium_? 10. _Tetrapyle polyacantha_, fig. 44 = _Larcarium_? 11. _Flustrella cyclica_, fig. 19 = _Porodiscus_. 12. _Flustrella micromma_, fig. 47 = _Porodiscus_. 13. _Rhopalastrum bandaicum_, fig. 45 = _Dictyastrum_. 14. _Lithocyclia reticulata_, fig. 20 = _Spongodiscus_?

II. NASSELLARIA.

15. _Lithocircus annulus_, fig. 50 = _Lithocircus_. 16. _Acanthodesmia arcuata_, fig. 25 = _Zygostephanus_. 17. _Acanthodesmia inermis_, fig. 26 = _Dictyospyris_? 18. _Cladospyris moluccana_, fig. 48 = _Cyphonium_? 19. _Podocyrtis brevipes_, fig. 24 = _Podocyrtis_. 20. _Podocyrtis micracantha_, fig. 49 = _Podocampe_? 21. _Lithocampe corbula_, fig. 21 = _Lithomitra_. 22. _Lithocampe sinuosa_, fig. 22 = _Lithocampe_?

II. _List of Fossil Radiolaria (probably Jurassic) found in the "Diaspri della Toscana," and described in 1880 by Dante Pantanelli_ (L. N. 36). (_Compare_ § 243, _Note_ B, p. clxviii).

The figures are too small and too incomplete for certain determination.

I. SPUMELLARIA.

1. _Ethmosphæra minuta_. 2. _Ethmosphæra vulgaris_. 3. _Ethmosphæra siphonophora_. 4. _Heliosphæra echinoidites_. 5. _Rhaphidococcus lusianensis_. 6. _Heliodiscus simplex_. 7. _Histiastrum lusianense_. 8. _Trematodiscus soritoides_. 9. _Euchitonia muellerites_. 10. _Euchitonia amoena_. 11. _Euchitonia clathrata_. 12. _Euchitonia crevolensis_. 13. _Euchitonia grandis_. 14. _Euchitonia dubia_.

II. NASSELLARIA.

15. _Lithocircus haeckelii_. 16. _Lithocircus truncatus_. 17. _Lithocircus rhombus_. 18. _Cornutella pseudoprofunda_. 19. _Cornutella pseudoclathrata_. 20. _Lithopera ovata_. 21. _Lithopera elongata_. 22. _Polystichia ehrenbergii_. 23. _Polystichia haeckelii_. 24. _Polystichia muelleri_. 25. _Urocyrtis emmæ_. 26. _Urocyrtis amaliæ_. 27. _Urocyrtis stephanii_. 28. _Adelocyrtis cometa_. 29. _Adelocyrtis pala_. 30. _Adelocyrtis spinosa_.

ERRATA.

Page 23, line 3 from top, _add_ "Compare also _Myxobrachia cienkowski_, Wagner, 1872, L. N. 23."

Page 40, bottom line, _add_ "The two following species are incompletely known:--_Sphærozoum orientale_, Dana, 1863, _Ann. and Mag. Nat. Hist._, vol. xii. p. 54. _Sphærozoum sanderi_, Doenitz, 1871, L. N. 60, p. 71."

Page 65, line 15 from top, _add_ "_Cenosphæra radiata_, Zittel, 1876 (L. N. 29, p. 84, Taf. ii. figs. 7, 8), a fossil Cretaceous species, is closely allied to _Cenosphæra compacta_."

Page 84, line 17 from top, _add_ "_Caryosphæra polysphærica_, Bütschli, 1882 (L. N. 41, Taf. xxiii. fig. 12) is probably a _Cromyosphæra_ (fossil in Barbados)."

Page 95, line 11 from top, _add_ "_Dermatosphæra_, Ehrenberg, is a _Collosphæra_ with small pores (compare L. N. 16, p. 533)."

Page 97, line 8 from foot, _for_ "xxiv." _read_ "xxxiv."

Page 122, line 14 from foot, _for_ "_Spongolonche_" _read_ "_Spongolonchis_."

Page 149, lines 1, 4, 6 and 12 from top, _for_ "_Spongolonche_" _read_ "_Spongolonchis_."

Page 149, line 2 from foot, _for_ "_Spongolonche_" _read_ "_Spongolonchis_ ([Greek: spongos], [Greek: lonchis])."

Page 172, line 4 from foot, _add_ Synonym "? _Haliphormis hexacantha_, Ehrenberg, 1872, L. N. 24, Taf. x. fig. 6."

Page 216, line 11 from foot, _add_ "Taf. xiii."

Page 308, line 4 from top, _add_ "Compare _Haliomma oblongum_, Harting, 1863, L. N. 18, p. 15, pl. 2, fig. 42."

Page 326, line 14 from foot, _for_ "1872" _read_ "1875."

Page 461, line 12 from foot, _delete_ "H."

Page 463, line 10 from top, _add_ "Indian Ocean, Cocos Islands, Rabbe."

Page 492, bottom line, _add_ "_Porodiscus haeckelii_ = _Trematodiscus haeckelii_, Bütschli, 1882, L. N. 41, Taf. xxiv. figs. 5_a_, 5_b_."

Page 509, bottom line, _add_ "_Stylodictya haeckelii_, Zittel, 1876, L. N. 29, p. 85, Taf. ii. fig. 9, is a fossil Cretaceous species, related to _Stylodictya multispina_."

Page 534, line 11 from foot, _add_ "Indian Ocean, Cocos Islands (Rabbe). Also in the Central Pacific, Station 267."

Page 584, line 12 from top, _for_ "1872" _read_ "1875."

Page 586, line 7 from foot, _add_ "_Spongotrochus ehrenbergii_, Bütschli, 1882, L. N. 41, Taf. xxvi. figs. 1_a_, 1_b_."

Page 633, bottom line, _add_ "_Monozonium hartingii_ = _Haliomma amphiaspis_, Harting, 1863 (L. N. 18, p. 15, pl. 2, fig. 43)."

Page 763, line 8 from top, _add_ "Pl. 132, fig. 11."

Page 784, line 16 from top, _for_ "vi." _read_ "xvi."

Page 802, line 14 from bottom, _after_ "11_a_" _insert_ "11_c_."

Page 839, line 13 from top, _for_ "95" _read_ "135."

Page 841, line 8 from foot, _after_ "figs." _insert_ "2."

Page 842, line 13 from top, _add_ "_Haliomma ligurinum_, J. Müller (= _Haliommatidium ligurinum_, Haeckel, L. N. 16, p. 423) seems to be closely allied to the preceding."

Page 889, line 6 from top, _add_ "_Cricoidea_, Bütschli, 1882 (L. N. 40, p. 537) = NASSELLARIA."

Page 951, line 9 from foot, _add_ "Fossil in Barbados."

Page 952, line 2 from foot, _add_ "Fossil in Barbados."

Page 966, line 10 from top, _add_ "Fossil in Barbados."

Page 981, line 19 from top, _add_ "Fossil in Barbados."

Page 1037, line 8 from top, _add_ "Pl. 85, fig. 2."

Page 1081, line 12 from foot, _add_ "Pl. 95, fig. 15."

Page 1158, line 10 from foot, _for_ "516. _Cyrtophormis_" _read_ "516. _Cystophormis_."

Page 1165, lines 8, 11 and 15 from foot, _for "Cyrtophormis" read "Cystophormis_."

Page 1165, bottom line, _read_ "_Cystophormis_ = bladder-basket; [Greek: kystê], [Greek: phormis]."

Page 1166, lines 1, 7 and 13 from top, _for_ "_Cyrtophormis_" _read_ "_Cystophormis_."

Page 1250, line 7 from top, _for_ "_Dictyoprora_" _read_ "_Dictyoprona_."

Page 1251, line 11 from top, _add_ "Pl. 62, fig. 3."

Page 1356, line 9 from foot, _add_ "Pl. 68, fig. 14."

Page 1384, line 2 from foot, _for_ "_Calocycloma_" _read_ "_Calocyclura_."

Page 1411, first line, _add_ "Pl. 68, fig. 15."

Page 1560, line 2 from top, _add_ "_Dictyocha trigona_, Zittel, 1876 (L. N. 29, p. 83, Taf. ii. fig. 6), is an interesting Cretaceous species, perhaps a variety of _Dictyocha triommata_."

Page 1615, line 6 from top, _insert_ "n. sp." _after_ "_scenophora_."

Page 1653, line 7 from top, _add_ "John Murray, 1876, L. N. 27, pl. 24, fig. 2."

Page 1706, line 7 from foot, _add_ "John Murray, 1876, L. N. 27, pl. 24, fig. 4."

Page 1752, line 4 from bottom, _for_ "figs. 1_a_-1_d_" _read_ "figs. 1_a_-1_c_."

Page 1757, line 14 from bottom, _for_ "fig. 1" _read_ "figs. 1-13."

Page 1759, line 14 from bottom _for_ "figs. 4_a_, 4_b_" read "figs. 4, 4_a_."

INDEX.

Synonyms are printed in _Italics_; names of Families, Orders, &c., in CAPITALS.

ACANTHARIA, 716. Acanthochiasma, 739. fusiforme, 739. krohnii, 739. rubescens, 739. spirale, 739. ACANTHOCHIASMIDA, 738. Acanthocorallium, 1262. Acanthocoronium, 1263. Acanthocorys, 1261. bütschlii, 1262. dodecaster, 1264. enneapodia, 1263. furcata, 1264. hexapodia, 1262. macroceras, 1264. macropodia, 1262. polypodia, 1264. pristipodia, 1262. triloba, 1263. umbellifera, 1263. Acanthocorythium, 1264. Acanthocyrtis, 1494. Acanthocystis, 1461. Acanthodesmia, 975. _arcuata_, 1761. ceratospyris, 976. corona, 976. _dumetum_, 930. _hertwigii_, 983. _inermis_, 1761. mülleri, 976. _polybrocha_, 930. _prismatium_, 1010. vinculata, 975. ACANTHODESMIDA, 973. Acantholithium, 753. Acantholonche, 790. amphipolaris, 790. peripolaris, 791. ACANTHOLONCHIDA, 781. ACANTHOMETRA, 725. _Acanthometra_, 742. _alata_, 761. _anomale_, 789. _arachnoides_, 910. _belonoides_, 783. _brevispina_, 745. _bulbosa_, 743. _cataphracta_, 810. _claparedei_, 751. _complanata_, 786. _compressa_, 747. _costata_, 812. _cruciata_, 754. _cuspidata_, 752. _dichotoma_, 747. _dolichoscia_, 743. _echinoides_, 751. _elastica_, 742. _elongata_, 785. _forceps_, 770. _fragilis_, 750. _furcata_, 747. _fusca_, 743. _hastata_, 770. _hemicompressa_, 748. _heteracantha_, 784. _lanceolata_, 746. _messanensis_, 786. _mucronata_, 756. _mülleri_, 750. _multispina_, 752. _ovata_, 785. _pallida_, 770. _pectinata_, 757. _pellucida_, 744. _purpurascens_, 769. _quadridentata_, 758. _quadrifolia_, 752. _serrata_, 757. _sicula_, 744. _spinulosa_, 759. _tenuis_, 784. _tetracopa_, 749. _tetraptera_, 787. _wageneri_, 744. ACANTHOMETREA, 716. Acanthometrella, 742. ACANTHOMETRIDA, 725. Acanthometron, 742. bifidum, 745. bulbiferum, 745. bulbosum, 743. catervatum, 745. conicum, 743. cylindricum, 743. dolichoscion, 743. elasticum, 742. fuscum, 743. pellucidum, 744. siculum, 744. wageneri, 744. Acanthonarium, 749. Acanthonia, 751. claparedei, 751. concava, 750. convexa, 750. cuspidata, 752. denticulata, 750. diplopyramis, 752. echinoides, 751. fragilis, 750. mülleri, 750. multispina, 752. prismatica, 749. quadrangula, 751. quadrifolia, 752. serrulata, 753. stellata, 753. tetracopa, 749. ACANTHONIDA, 740. Acanthonidium, 751. ACANTHOPHRACTA, 791. ACANTHOPHRACTIDA, 791. Acanthosphæra, 209. acanthica, 215. acufera, 211. angulata, 216. antarctica, 214. arctica, 214. brevispina, 215. capillaris, 214. castanea, 211. clavata, 212. compacta, 213. conifera, 216. _coronata_, 219. dentata, 211. echinoides, 214. _elliptica_, 350. enneacantha, 213. florida, 213. flosculenta, 211. fortispina, 212. gibbosa, 216. haliphormis, 215. insignis, 212. longispina, 215. macropora, 210. marginata, 212. maxima, 216. micropora, 210. mucronata, 212. octahedralis, 213. _pectinata_, 218. reticulata, 217. _setosa_, 174. simplex, 216. tenuis, 210. tenuissima, 210. _zonaster_, 281. ACANTHOSTAURIDA, 768. Acanthostaurus, 769. æquatorialis, 769. bipennis, 769. conacanthus, 769. cruciatus, 771. forceps, 770. hastatus, 770. pallidus, 770. purpurascens, 769. Acontasparium, 829. Acontaspidium, 829. Acontaspis, 829. capillata, 830. furcata, 829. hastata, 829. lanceolata, 829. Acostaurus, 769. Acrobotrys, 1114. acuminata, 1115. aquaria, 1114. auriculata, 1115. disolenia, 1114. monosolenia, 1114. pentasolenia, 1115. tetrasolenia, 1115. trisolenia, 1115. Acrocalpis, 1168. _virginica_, 1169. Acrocorona, 1176. Acrocoronis, 977. Acrocubus, 992. amphistylus, 993. amphithectus, 994. arcuatus, 993. brachiatus, 993. cortina, 994. lasanum, 994. octopylus, 993. tesseralis, 993. tetrapodius, 994. Acromelissa, 1203. Acropyramis, 1159. Acrosphæra, 99. collina, 101. echinoides, 100. erinacea, 100. inflata, 101. setosa, 100. spinosa, 100. ACROSPHÆRIDA, 94. ACROSPYRIDA, 1085. Acrospyris, 1085. clathrocanium, 1085. dictyophimus, 1085. fragilis, 1086. macrocephala, 1085. pyramidalis, 1086. Actidiscus, 15. _discoides_, 15. _lenticularis_, 15. _phacoides_, 15. Actilarcus, 16. _larcoides_, 16. Actinastrum, 733. legitimum, 733. pentazonium, 733. Actinelarium, 730. ACTINELIDA, 728. Actinelidium, 730. Actinelius, 730. pallidus, 731. polyacanthus, 731. primordialis, 730. protogenes, 730. purpureus, 730. Actinelonium, 731. Actinomma, 251. _aculeatum_, 258. anthomma, 252. arcadophorum, 255. _asteracanthion_, 196. capillaceum, 255. castanomma, 253. crenatum, 314. _daturæforme_, 164. denticulatum, 254. dodecomma, 256. drymodes, 198. entactinia, 253. facetum, 252. _fenestratum_, 315. giganteum, 256. _hexactis_, 192. hexagonium, 252. hirsutum, 251. _inerme_, 80. japonicum, 253. _medusa_, 80. pachycapsa, 256. pachyderma, 254. schwageri, 256. _sphærechinus_, 258. spinigerum, 254. _tetracanthum_, 164. trinacrium, 254. _triplex_, 314. ACTINOMMATIDA, 251. Actinommida, 251. Actinopyramis, 1256. Actiprunum, 14. _ellipsoides_, 14. _prunoideum_, 14. ACTIPYLEA, 716. Actissa, 12. discoides, 15. ellipsoides, 14. larcoides, 16. lenticularis, 15. phacoides, 13. primordialis, 13. princeps, 13. prototypus, 13. prunoides, 14. radiata, 14. ADELACANTHA, 717. Adelocyrtis, 1762. cometa, 1762. pala, 1762. spinosa, 1762. Aegospyris, 1053. aegoceras, 1054. aequispina, 1053. caprina, 1054. longibarba, 1054. octospina, 1053. Alacorys, 1370. aculeata, 1373. bismarckii, 1372. carcinus, 1375. dodecantha, 1375. enneacantha, 1374. friderici, 1372. gigas, 1374. guilelmi, 1372. hexacantha, 1373. hexapleura, 1373. lutheri, 1370. octacantha, 1374. ornata, 1375. pentacantha, 1371. polyacantha, 1375. tetracantha, 1371. Amphiactura, 470. _diploconus_, 470. amphibrachia, 470. Amphibelithium, 790. Amphibelone, 788. aciculata, 788. anomala, 789. clavaria, 790. cultellata, 789. pyramidata, 789. Amphibelonium, 788. Amphibrachium, 516. amphilonche, 517. armatum, 518. capitatum, 518. clavula, 518. dilatatum, 517. indicum, 518. lanceolatum, 517. murrayanum, 523. sponguroides, 517. _Amphicentria_, 614. _salpa_, 614. Amphicraspedum, 523. maclaganium, 523. murrayanum, 523. wyvilleanum, 523. Amphicyclia, 463. amphistylia, 464. chronometra, 463. pachydiscus, 464. AMPHILITHIDA, 781. Amphilithium, 787. Amphiloncharium, 783. Amphilonche, 783. acufera, 788. _anomala_, 789. belonoides, 783. complanata, 786. concreta, 787. conica, 785. denticulata, 784. diodon, 783. elongata, 785. heteracantha, 384. hydrotomica, 786. lanceolata, 783. lancetta, 786. messanensis, 786. ovata, 785. tenuis, 784. tetraptera, 787. violina, 787. AMPHILONCHIDA, 781. Amphilonchidium, 785. Amphiplecta, 1223. acrostoma, 1223. amphistoma, 1223. callistoma, 1224. Amphipyle, 641. aceros, 641. amphiceros, 691. amphiptera, 642. callizona, 644. cladoceros, 643. decaceros, 643. hexaceros, 642. octoceros, 643. platyptera, 641. stauroceros, 642. stenoptera, 641. tetraceros, 642. Amphipylonium, 656. octoceras, 657. semilunare, 656. spinosissimum, 657. tetraceros, 657. Amphirrhopalum, 521. amphidicranum, 521. bigeminum, 522. echinatum, 522. ximorphum, 521. ypsilon, 532. Amphisphæra, 142. apollo, 143. cronos, 144. jupiter, 143. mars, 144. mercurius, 143. neptunus, 142. pluto, 144. uranus, 143. Amphispyridium, 1096. Amphispyris, 1095. costata, 1097. quadrigemina, 1096. reticulata, 1096. sternalis, 1096. subquadrata, 1097. thorax, 1096. toxarium, 1097. Amphispyrium, 1095. AMPHISTYLIDA, 142. Amphistylus, 145. clio, 145. _giganteus_, 329. glyptodon, 145. hippocampus, 145. _neptunus_, 328. AMPHITHOLIDA, 663. Amphitholonium, 668. acanthonium, 669. octostylonium, 669. tricolonium, 669. Amphitholus, 666. acanthometra, 667. armatus, 668. artidium, 666. artiscus, 666. dodecanthus, 667. octacanthus, 667. panicium, 668. polyacanthus, 668. Amphymenium, 519. amphistylium, 520. fusiforme, 521. monstrosum, 520. naviculare, 519. pupula, 519. zygartus, 520. ANDROSPYRIDA, 1090. Androspyris, 1092. anthropiscus, 1093. aptenodytes, 1093. homunculus, 1092. pithecus, 1093. Anthocorys, 1456. _campanula_, 1456. Anthocyrtarium, 1272. Anthocyrtella, 1269. ANTHOCYRTIDA, 1241. Anthocyrtidium, 1278. cineraria, 1278. ligularia, 1278. matricaria, 1279. Anthocyrtis, 1269. butomus, 1270. _collaris_, 1273. _cothurnata_, 1353. _ehrenbergii_, 1277. enneaphylla, 1271. _ficus_, 1277. _flosculus_, 1277. furcata, 1269. grossularia, 1271. hispida, 1275. lauranthus, 1271 _leptostyla_, 1275. mespilus, 1269. ophirensis, 1270. ovata, 1272. _serrulata_, 1268. _sethoconus_, 1296. _setosa_, 1276. subglobosa, 1271. ventricosa, 1270. _zanguebarica_, 1277. Anthocyrtissa, 1270. Anthocyrtium, 1272. adonis, 1273. anemone, 1274. anthemis, 1273. campanula, 1274. centaurea, 1273. chrysanthemum, 1272. collare, 1273. doronicum, 1276. ehrenbergii, 1277. ficus, 1277. flosculus, 1277. hispidum, 1275. leptostylum, 1275. pyrum, 1276. reticulatum, 1274. setosum, 1276. turris, 1275. zanguebaricum, 1277. Anthocyrtoma, 1268. alterna, 1268. serrulata, 1268. Anthocyrtonium, 1274. Anthocyrtura, 1271. Anthocyrturium, 1276. _Anthomma_, 76. _nodusum_, 76. Anthospyris, 1064. aculeata, 1065. arachnoides, 1065. diaboliscus, 1065. doronicum, 1065. mammillata, 1064. spathulata, 1065. tragopogon, 1066. Apocubus, 992. Arachnocalpis, 1172. ellipsoides, 1172. sphæroides, 1173. Arachnocorallium, 1265. Arachnocoronium, 1266. Arachnocorys, 1265. arachnodiscus, 1267. araneosa, 1266. circumtexta, 1266. discoides, 1265. enneaptera, 1266. hexaptera, 1265. polyptera, 1267. trifida, 1267. _umbellifera_, 1263. Arachnocorythium, 1267. Arachnopegma, 267. increscens, 267. longispinum, 267. verticillatum, 267. Arachnopila, 266. hexagonella, 266. polygonella, 266 Arachnopilium, 1327. _clathrocanium_, 1327. Arachnosphæra, 268. dolichacantha, 269. increscens, 269. myriacantha, 268. oligacantha, 268. tenuissima, 269. velaris, 269. ARACHNOSPHÆRIDA, 265. Archibursa, 1157. tripodiscus, 1157. Archicapsa, 1191. nonaforis, 1192. quadriforis, 1192. triforis, 1191. ARCHICAPSIDA, 1189. Archicircus, 940. duodenus, 942. ellipsis, 941. hertwigii, 942. hexacanthus, 942. monopylus, 941. monostephus, 941. ovalis, 941. primordialis, 942. princeps, 940. quadratus, 941. rhombus, 942. sexangularis, 943. triglyphus, 943. ARCHICORIDA, 1180. Archicorys, 1184. ampulla, 1184. galea, 1184. globosa, 1185. microstoma, 1185. ovata, 1185. ARCHIDISCIDA, 485. Archidiscus, 486. dioniscus, 486. dithalamus, 486. hexathalamus, 489. hexoniscus, 488. octoniscus, 489. pentoniscus, 488. polythalamus, 489. pylonsicus, 488. stauroniscus, 487. tetrathalamus, 487. tetroniscus, 487. trioniscus, 487. trithalamus, 487. Archipera, 1155. bicornis, 1156. cortiniscus, 1155. multicornis, 1156. pentacantha, 1155. quadricornis, 1156. tricornis, 1156. ARCHIPERIDA, 1146. Archiperidium, 1154. Archiphæna, 1177. corona, 1178. gorgospyris, 1178. stephanoma, 1178. ARCHIPHÆNIDA, 1173. ARCHIPHORMIDA, 1159. Archiphormis, 1167. campanulata, 1165. cancellata, 1167. urceolata, 1168. ARCHIPILIDA, 1135. Archipilium, 1139. cyrtopterum, 1140. orthopterum, 1139. sigmopterum, 1139. Archiscenium, 1150. callimitra, 1151. clathrocorys, 1150. cyclopterum, 1151. quadrispinum, 1150. _tricolpium_, 1147. tripterygium, 1151. Archistephus, 941. Artidium, 356. ARTINIDA, 354. Artiscium, 355. Artiscus, 355. elegans, 356. facetus, 355. hystrix, 356. nodosus, 356. panarius, 356. paniculus, 355. paniscus, 355. Artocapsa, 1519. armata, 1520. elegans, 1520. fusiformis, 1519. infraculeata, 1519. octocamera, 1520. quadricamera, 1520. spinosa, 1519. ARTOCAPSIDA, 1467. ARTOCORIDA, 1467. Artocyrtis, 1490. Artopera, 1452. fusiformis, 1452. loxia, 1452. motacilla, 1452. _thoracoptera_, 1450. ARTOPERIDA, 1435. Artophæna, 1463. ærostatica, 1463. hexalatractus, 1464. hexapodiscus, 1464. senaria, 1464. ARTOPHÆNIDA, 1453. ARTOPHORMIDA, 1453. Artophormis, 1458. barbadensis, 1459. costata, 1459. horrida, 1458. ARTOPILIDA, 1435. Artopilium, 1439. anomalum, 1442. cornutella, 1441. cyrtopterum, 1440. elegans, 1440. longicorne, 1440. stichopterygium, 1442. trifenestra, 1441. trigonopterum, 1441. Artostrobium, 1482. Artostrobulus, 1481. Artostrobus, 1481. annulatus, 1481. articulatus, 1482. auritus, 1482. biseriatus, 1482. elegans, 1482. _Aspidomma_, 847. _hystrix_, 854. _mucronatum_, 756. Astractinium, 476. Astractura, 476. aristotelis, 476. clavigera, 476. democriti, 477. hippocratis, 477. ordinata, 476. ASTRACTURIDA, 469. Astracturium, 476. Astrocapsa, 799. coronata, 799. quadrifida, 799. stellata, 799. tritonis, 799. ASTROCAPSIDA, 797. Astrocyclia, 466. arachnia, 467. heterocycla, 468. rotula, 467. solaster, 466. stella, 467. ASTROCYRTIDA, 1129. ASTROLITHIDA, 726. Astrolithium, 745. _bifidum_, 745. _bulbiferum_, 745. _cruciatum_, 771. _dicopum_, 748. Astroloncharium, 756. Astrolonche, 756. bicruciata, 756. mucronata, 756. pectinata, 757. pinnata, 757. serrata, 757. ASTROLONCHIDA, 740. Astrolonchidium, 757. ASTROLOPHIDA, 728. Astrolophus, 732. solaris, 732. stellaris, 732. _Astromma_, 475. _aristotelis_, 476. _entomocora_, 367. _pentactis_, 479. _pythagoræ_, 471. Astrophacus, 453. apollinis, 455. asteriscus, 453. cingillum, 454. phacodiscus, 454. saturnus, 454. solaris, 453. trochiscus, 453. Astrosestrum, 442. acanthastrum, 443. acraspedum, 443. _caudatum_, 431. echinastrum, 443. ephyra, 442. floscula, 444. nauphanta, 442. octacanthum, 442. pelagia, 444. Astrosphæra, 250. hexagonalis, 250. splendens, 250. sideræa, 251. stellata, 251. ASTROSPHÆRIDA, 206. Astrostaurus, 436. _magnificus_, 436. Astrostylus, 431. Atactodiscus, 497. _irregularis_, 498. Aulacantha, 1575. cannulata, 1576. clavata, 1576. lævissima, 1576. scolymantha, 1575. spinosa, 1575. tubulosa, 1575. AULACANTHIDA, 1569. AULACTINIDA, 1573. Aulactinium, 1574. actinastrum, 1574. actinelium, 1574. actinosphærium, 1574. Aularia, 1621. ternaria, 1621. trigonaria, 1621. tubularia, 1621. AULARIDA, 1620. Aulastrum, 1635. dendroceros, 1635. dichoceros, 1635. monoceros, 1635. pentaceros, 1636. polyceros, 1636. tetraceros, 1636. triceros, 1635. trichoceros, 1636. Aulatractus, 1632. diploconus, 1632. ellipsoides, 1633. fusiformis, 1632. fusulus, 1632. Auloceræa, 1583. Auloceratium, 1585. Auloceros, 1583. arborescens, 1585. capreolus, 1584. cervinus, 1584. dicranaster, 1585. elegans, 1584. furcosus, 1583. spathillaster, 1585. trigeminus, 1584. Aulodendron, 1588. antarcticum, 1589. atlanticum, 1589. australe, 1589. indicum, 1590. pacificum, 1589. Aulodictyum, 1637. hydrodictyum, 1637. Aulographantha, 1577. Aulographella, 1579. AULOGRAPHIDA, 1574. Aulographidium, 1580. Aulographis, 1577. asteriscus, 1581. ancorata, 1578. bovicornis, 1577. candelabrum, 1582. cruciata, 1578. dentata, 1582. flammabunda, 1579. flosculus, 1580. furcula, 1580. gemmascens, 1580. hexancistra, 1581. martagon, 1579. pandora, 1577. penicillata, 1578. pistillum, 1579. polyancistra, 1581. pulvinata, 1582. serrulata, 1582. stellata, 1578. taumorpha, 1577. tetrancistra, 1581. triæna, 1579. triangulum, 1580. triglochin, 1578. tripentas, 1582. verticillata, 1582. Aulographonium, 1581. Aulonia, 1633. hexagonia, 1634. metagonia, 1634. pentagonia, 1634. polygonia, 1634. tetragonia, 1633. AULONIDA, 1633. Aulophacus, 1631. amphidiscus, 1631. lenticularis, 1631. Auloplegma, 1630. perplexum, 1630. spongiosum, 1631. Auloscena, 1628. arboretum, 1629. flammabunda, 1629. gigantea, 1629. mirabilis, 1628. penicillus, 1629. pyramidalis, 1628. serrata, 1630. spectabilis, 1628. tentorium, 1628. verticillus, 1629. Aulospathessa, 1586. Aulospathilla, 1587. Aulospathis, 1586. bifurca, 1586. diodon, 1587. furcata, 1588. hexodon, 1588. polymorpha, 1587. quadrifurca, 1587. tetrodon, 1588. trifurca, 1586. triodon, 1587. variabilis, 1588. Aulosphæra, 1622. bifurca, 1626. bisternaria, 1624. coronata, 1626. cruciata, 1624. dendrophora, 1625. diodon, 1623. elegantissima, 1624. flexuosa, 1622. _gracilis_, 1609. multifurca, 1626. polyodon, 1623. _pourtalesii_, 1624. quadrifurca, 1626. sceptrophora, 1625. spathillata, 1624. spathophora, 1625. spinosa, 1627. tetrodon, 1623. trifurca, 1626. trigonopa, 1622. triodon, 1623. undulata, 1627. verticillata, 1624. AULOSPHÆRIDA, 1615. Axellipsis, 293. lobata, 293. perforata, 293. Axocorys, 1420. macroceros, 1420. Axodiscus, 490. hexagonus, 490. octogonus, 491. spinosus, 491. staurophorus, 490. stylophorus, 490. trigonus, 490. triradiatus, 490. Axoprunum, 298. stauraxonium, 298.

Bathropyramis, 1159. acephala, 1159. interrupta, 1160. medusa, 1160. quadrata, 1159. ramosa, 1161. spinosa, 1160. trapezoides, 1160. BELOIDEA, 28. BELONASPIDA, 859. Belonaspis, 863. conifera, 864. datura, 863. furcata, 863. lanceolata, 864. multiforis, 864. pandanus, 863. Belonostaurus, 771. bicuspis, 772. quadratus, 771. Belonozoum, 39. atlanticum, 40. bacillosum, 39. italicum, 40. spinulosum, 40. BOTRIDA, 1103. BOTRYIDA, 1103. Botryocampe, 1122. camerata, 1124. galea, 1123. hexathalamia, 1125. inflata, 1123. rotalia, 1123. theocapsa, 1123. BOTRYOCAMPIDA, 1120. Botryocella, 1116. borealis, 1116. multicellaris, 1112. nucula, 1116. quadricellaris, 1117. quadrigemina, 1117. tricellaris, 1116. BOTRYOCELLIDA, 1112. BOTRYOCYRTIDA, 1120. Botryocyrtis, 1120. cerebellum, 1121. quinaria, 1121. serpentis, 1120. theocampe, 1121. BOTRYODEA, 1108. Botryopera, 1108. cyrtoloba, 1108. multiloba, 1109. quadriloba, 1109. triloba, 1108. Botryopyle, 1112. cephalodes, 1113. cribrosa, 1113. dictyocephalus, 1113. inclusa, 1113. sethocorys, 1112. BOTRYOPYLIDA, 1112. Botryostrobus, 1475. Brachiospyris, 1037. diacantha, 1038. ocellata, 1038. Buccinosphæra, 99. invaginata, 99. tubaria, 99.

Callimitra, 1216. agnesæ, 1217. annæ, 1217. carolotæ, 1217. elisabethæ, 1218. emmæ, 1218. Calocyclas, 1381. amicæ, 1382. aspasia, 1385. _barbadensis_, 1459. _carcinus_, 1375. casta, 1384. erinaceus, 1383. gigas, 1384. hyalogaster, 1383. minervæ, 1382. monumentum, 1385. parthenia, 1385. pudica, 1384. sacerdotis, 1382. turris, 1383. veneris, 1381. vestalis, 1382. virginis, 1381. Calocycletta, 1381. Calocyclissa, 1383. Calocycloma, 1384. CALODICTYA, 481. Calpocapsa, 1190. Calpophæna, 1175. enneaphylla, 1176. ennearrhabda, 1176. hexacorethra, 1177. hexarrhabda, 1176. petalospyris, 1177. tetracorethra, 1177. tetrarrhabda, 1176. Caminosphæra, 111. dendrophora, 112. dichotoma, 112. elongata, 111. furcata, 111. Cannartidium, 373. amphicanna, 374. amphiconicum, 373. _amphiconus_, 372. amphisiphon, 374. bicinctum, 374. mammiferum, 375. mastophorum, 375. _tubarium_, 339. Cannartiscus, 372. amphiconiscus, 372. amphicylindrus, 373. Cannartus, 358. biscottus, 359. bitubulus, 359. violina, 358. CANNOBELIDA, 1551. Cannobelos, 1551. calymmata, 1551. cavispicula, 1551. thalassoplancta, 1551. CANNOBOTRYIDA, 1107. Cannobotrys, 1109. cortina, 1110. dicanna, 1110. monocanna, 1110. pentacanna, 1111. sagittalis, 1110. tetracanna, 1111. tricanna, 1110. Cannocapsa, 801. osculata, 801. stethoscopium, 801. tubulosa, 801. Cannopilus, 1567. calyptra, 1568. cyrtoides, 1569. diplostaurus, 1568. hemisphæricus, 1569. superstructus, 1568. CANNOPYLEA, 1521. CANNORRHAPHIDA, 1546. Cannorrhaphis, 1552. cavispicula, 1551. lampoxanthium, 1552. lappacea, 1552. spathillata, 1552. spinulosa, 1552. Cannosphæra, 1640. antarctica, 1640. atlantica, 1640. pacifica, 1641. CANNOSPHÆRIDA, 1637. Cantharospyris, 1050. ateuchus, 1051. carabus, 1051. platybursa, 1051. radicata, 1051. CAPSOPHRACTA, 793. Carpocanarium, 1279. Carpocanidium, 1280. Carpocanistrum, 1170. acephalum, 1171. evacuatum, 1172. flosculum, 1171. giganteum, 1171. novenum, 1171. pyriforme, 1172. Carpocanium, 1279. _arachnodiscus_, 1164. calycodes, 1279. _campanula_, 1144. _cornutum_, 1398. coronatum, 1284. cylindricum, 1281. dactylus, 1284. diadema, 1281. enneaphyllum, 1281. gemmula, 1282. hexagonale, 1282. irregulare, 1284. læve, 1280. lanceolatum, 1280. _macropterum_, 1283. microdon, 1282. palmipes, 1283. peristomium, 1283. petalospyris, 1283. polypterum, 1283. setosum, 1280. solitarium, 1281. trepanium, 1282. verecundum, 1284. virgineum, 1285. Carpocanobium, 1282. Carposphæra, 71. apiculata, 73. areca, 74. belladonna, 74. borassus, 75. capillacea, 72. cerasus, 73. corypha, 75. cubaxonia, 72. entactinia, 74. infundibulum, 72. maxima, 76. melissa, 73. melitomma, 73. micrococcus, 75. modesta, 74. nobilis, 75. nodosa, 76. prunulum, 74. CARPOSPHÆRIDA, 71. Caryomma, 265. irregulare, 266. regulare, 265. CARYOMMIDA, 265. Caryosphæra, 86. hexalepas, 86. pentalepas, 86. polysphærica, 1763. CARYOSPHÆRIDA, 85. CARYOSTYLIDA, 148. Caryostylus, 148. _ceparius_, 336. _cepicius_, 336. hexalepas, 148. Castanarium, 1681. darwini, 1681. hookeri, 1682. huxleyi, 1682. lubbocki, 1682. lyelli, 1682. Castanella, 1683. balfouri, 1683. campbelli, 1683. channeri, 1684. horstoni, 1684. sloggetti, 1683. thomsoni, 1683. wyvillei, 1683. CASTANELLIDA, 1677. Castanidium, 1684. aldrichii, 1685. bethelli, 1685. bromleyi, 1685. buchanani, 1685. moseleyi, 1686. murrayi, 1685. wildi, 1684. willemoesi, 1684. Castanissa, 1686. challengeri, 1686. crosbiei, 1687. hoylei, 1687. macleani, 1687. pearceyi, 1686. richardsi, 1687. Castanopsis, 1688. fergusoni, 1688. maclearei, 1688. naresi, 1688. Castanura, 1689. carpenteri, 1689. havergalli, 1689. swirei, 1689. tizardi, 1689. CATINULIDA, 1553. Catinulus, 1553. catillum, 1553. lopadium, 1553. quadrifidus, 1553. Cecryphalium, 1398. lamprodiscus, 1398. sestrodiscus, 1399. Cenellipsis, 291. circopora, 291. ehrenbergii, 291. faceta, 291. heteropora, 292. infundibulum, 292. maxima, 292. micropora, 291. oblonga, 293. ovulum, 292. primitiva, 291. Cenellipsium, 290. Cenellipsula, 292. Cenocapsa, 802. nirvana, 802. CENOCAPSIDA, 802. CENODISCIDA, 409. Cenodiscus, 411. lenticula, 412. phacoides, 411. rotula, 412. CENOLARCIDA, 606. Cenolarcus, 606. dimensivus, 607. lentellipticus, 607. minimus, 607. primordialis, 607. triaxonius, 607. Cenosphæra, 62. _acanthica_, 215. anthophora, 63. antiqua, 67. aspera, 68. bombus, 63. compacta, 65. coronata, 67. crassa, 65. cristata, 66. elysia, 64. eridani, 64. favosa, 62. gigantea, 67. hexagonalis, 62. hirsuta, 68. inermis, 62. lethe, 64. marginata, 67. maxima, 65. _megapora_, 155. melecta, 63. mellifica, 62. _micropora_, 155. nirwana, 65. papillata, 66. perforata, 66. plutonis, 64. polygonalis, 66. porophæna, 63. primordialis, 61. proserpinæ, 64. radiata, 1763. reticulata, 66. rosetta, 63. setosa, 64. solida, 65. tenerrima, 66. vesparia, 62. Centrocubus, 278. cladostylus, 278. octostylus, 278. polystylus, 278. Centrospira, 495. _perispongidium_, 495. Cephalopyramis, 1253. _enneactis_, 1254. Cephalospyris, 1034. cancellata, 1035. ovata, 1035. triangulata, 1035. Cerasosphæra, 73. _Ceratocyrtis_, 1281. _ampliata_, 1291. _cucullaris_, 1290. _mitra_, 1291. Ceratospyris, 1065. _acuminata_, 1080. allmersii, 1067. _articulata_, 1048. _ateuchus_, 1051. _borealis_, 1075. calorrhiza, 1069. carnerii, 1069. _clavata_, 1028. _diacantha_, 1038. _didiceros_, 1030. _dirrhiza_, 1039. echinus, 1068. _fibula_, 1082. _furcata_, 1031. _heptaceros_, 1038. krausei, 1068. _longibarba_, 1054. mülleri, 1068. mulderi, 1067. _ocellata_, 1038. pentagona, 1067. polygona, 1066. preyeri, 1068. radicata, 1051. ramosa, 1069. _setigera_, 1047. strasburgeri, 1068. _stylophora_, 1038. _triceros_, 1033. _triomma_, 1047. _turrita_, 1050. Ceriasparium, 819. CERIASPIDA, 813. Ceriaspidium, 820. Ceriaspis, 820. cicatricosa, 821. favosa, 821. icosahedra, 821. inermis, 821. lacunosa, 820. scrobiculata, 820. Ceriosphæra, 66. _perforata_, 66. Challengeranium, 1653. Challengerantha, 1648. Challengerebium, 1655. Challengeretta, 1649. Challengeria, 1694. aldrichii, 1653. _balfouri_, 1655. bidens, 1650. bromleyi, 1652. campbelli, 1650. cyrtodon, 1649. elephas, 1651. harstoni, 1650. havergalli, 1651. macleari, 1651. murrayi, 1653. naresii, 1648. pyramidalis, 1649. quadridens, 1652. sigmodon, 1649. sloggettii, 1649. _swirei_, 1654. thomsoni, 1650. tizardi, 1656. tridens, 1651. trifida, 1652. trigona, 1652. tritonis, 1649. wildi, 1653. xiphodon, 1648. CHALLENGERIDA, 1642. Challengeridium, 1656. Challengerilla, 1651. Challengeroma, 1652. Challengeron, 1654. balfouri, 1655. bathybium, 1658. bethelli, 1658. bisternum, 1657. buchanani, 1657. carpenterii, 1659. channeri, 1658. ciliatum, 1659. cochlear, 1654. crosbiei, 1657. diodon, 1654. fergusoni, 1656. golfense, 1655. heptacanthum, 1657. johannis, 1659. monodon, 1654. moseleyi, 1658. pearceyi, 1654. richardsii, 1655. swirei, 1654. tizardi, 1656. triangulum, 1656. triodon, 1655. willemoesii, 1659. wyvillei, 1660. Challengerosium, 1658. CHIASTOLIDA, 736. CHIASTOLIDINA, 738. Chiastolus, 738. amphicopium, 738. _Chilomma_, 454. _saturnus_, 454. Chitonastrum, 537. bathybium, 537. dicranoides, 538. jugatum, 537. lyra, 538. _regulare_, 539. triglochin, 537. Choenicosphæra, 102. flammabunda, 103. flosculenta, 103. murrayana, 102. nassiterna, 103. Cinclopyramis, 1161. cribellum, 1161. infundibulum, 1161. lithosestrum, 1162. Circogonia, 1698. dodecacantha, 1698. icosahedra, 1698. CIRCOGONIDA, 694. Circoniscus, 489. CIRCOPORIDA, 1689. Circoporus, 1694. characeus, 1695. hexastylus, 1695. octahedrus, 1695. sexfurcus, 1694. sexfuscinus, 1695. Circorrhegma, 1699. dodecahedra, 1699. Circospathis, 1696. furcata, 1696. novena, 1696. tetradeca, 1697. tetrodonta, 1697. Circosphæra, 63. CIRCOSPYRIDA, 1072. Circospyris, 1072. gigas, 1072. nucula, 1072. tridentata, 1072. Circostephanus, 1699. coronarius, 1699. polygonarius, 1700. sexagenarius, 1700. Circotympanum, 1012. decagonium, 1013. hexagonium, 1012. octogonium, 1013. Cladarachnium, 1165. _virgultum_, 1296. ramosum, 1165. CLADOCOCCIDA, 51. Cladococcus, 223. abietinus, 226. _acufer_, 211. antarcticus, 225. arborescens, 224. bifurcus, 226. _cervicornis_, 228. _dentatus_, 211. dendrites, 227. japonicus, 225. penicillus, 224. pinetum, 226. quadricuspis, 225. scoparius, 225. _simplex_, 216. spinifer, 224. stalactites, 227. tricladus, 227. viminalis, 226. Cladocorona, 1177. CLADOPHRACTA, 803. Cladopyramis, 1160. Cladoscenium, 1148. ancoratum, 1149. fulcratum, 1148. gladiatum, 1149. pectinatum, 1150. pinnatum, 1149. verticillatum, 1149. Cladospyris, 1069. _bibrachiata_, 1039. _moluccana_, 1761. _ramosa_, 1069. _tribrachiata_, 1029. _Clathrobursa_, 1045. _dictyopus_, 1045. Clathrocanidium, 1210. Clathrocanium, 1210. coarctatum, 1211. diadema, 1212. _ehrenbergii_, 1262. reginæ, 1212. sphærocephalum, 1211. squarrosum, 1211. triomma, 1211. Clathrocorona, 1212. _diadema_, 1212. _reginæ_, 1212. Clathrocorys, 1219. giltschii, 1220. murrayi, 1219. teuscheri, 1220. Clathrocircus, 961. decaporus, 962. dictyospyris, 963. hexaporus, 962. multiforis, 963. octoporus, 962. stapedius, 962. Clathrocyclas, 1385. alcmenæ, 1388. basilea, 1386. cassiopeiæ, 1390. collaris, 1387. coscinodiscus, 1389. danaës, 1388. domina, 1387. europæ, 1388. fimbriata, 1386. jonis, 1389. latonæ, 1389. principessa, 1386. puella, 1387. semeles, 1388. Clathrocyclia, 1386. Clathrolychnus, 1240. araneosus, 1240. periplectus, 1241. Clathromitra, 1218. pentacantha, 1219. pterophormis, 1219. Clathropilium, 1326. Clathropyrgus, 1441. _trifenestra_, 1441. Clathrosphæra, 118. arachnoides, 119. circumtexta, 118. lamellosa, 119. CLATHROSPHÆRIDA, 118. Clathrospyris, 1052. camelopardalis, 1052. fusiformis, 1053. pyramidalis, 1052. Clistophæna, 1286. armata, 1288. enneolena, 1288. hexolena, 1287. polyolena, 1288. pyramidalis, 1287. rüstiana, 1287. Coccocyclia, 468. heliantha, 468. liriantha, 468. COCCODISCIDA, 455. Coccodiscus, 461. darwinii, 461. goethei, 461. lamarckii, 461. COCCOLARCIDA, 610. Coccolarcus, 610. lentellipsis, 610. platellipsis, 610. Coccostaurus, 466. _magniducis_, 466. Coelacantha, 1641. anchorata, 1641. mammillata, 1641. Coelagalma, 1759. mirabile, 1759. Coelodasea, 1739. ramosissima, 1739. spongiosa, 1739. Coelodecas, 1755. decastyla, 1755. pentagona, 1756. sagittaria, 1755. COELODENDRIDA, 1728. Coelodendrum, 1735. bifurcum, 1735. cervicorne, 1736. digitatum, 1736. flabellatum, 1737. furcatissimum, 1735. gracillimum, 1736. lappaceum, 1736. ramosissimum, 1735. serratum, 1737. spinosissimum, 1735. Coelodoras, 1734. hexagraphis, 1734. octographis, 1734. COELODORIDA, 1733. COELODRYMIDA, 1737. Coelodrymus, 1738. ancoratus, 1738. echinatus, 1738. lappulatus, 1738. COELOGRAPHIDA, 1739. Coelographis, 1752. gracillima, 1753. hexastyla, 1753. regina, 1752. sagittella, 1753. triangulum, 1753. Coeloplegma, 1757. atlanticum, 1758. murrayanum, 1757. tetradecastylum, 1758. tritonis, 1758. COELOPLEGMIDA, 1752. Coelospathis, 1754. ancorata, 1754. octodactyla, 1755. octostyla, 1754. Coelostylus, 1756. bisenarius, 1756. flabellatus, 1757. Coelothamnus, 1751. bivalvis, 1751. davidoffi, 1751. maximus, 1752. sedecimalis, 1751. Coelothauma, 1750. duodenum, 1750. COELOTHOLIDA, 1749. Coelotholus, 1749. ancoratus, 1749. cruciatus, 1749. octonus, 1749. COLEASPIDA, 861. Coleaspis, 867. amphilonche, 867. coronata, 866. hydrotomica, 867. obscura, 866. occulta, 867. vaginata, 866. COLLIDA, 9. COLLODARIA, 9. Collodastrum, 27. amoeboides, 28. pelagicum, 28. stellatum, 28. Collodinium, 24. _inerme_, 25. _nostochinum_, 25. _volvocinum_ 25. Collodiscus, 27. _coeruleus_, 27. _discoideus_, 27. COLLOIDEA, 10. Collophidium, 26. _contortum_, 26. _serpentinum_, 26. _vermiforme_, 27. Colloprunum, 25. _ovatum_, 25. _ellipsoides_, 26. Collosphæra, 95. globularis, 95. huxleyi, 96. irregularis, 97. _ligurina_, 97. polyhedra, 97. polygona, 96. primordialis, 95. pyriformis, 96. regularis, 95. _spinosa_, 100. tuberosa, 97. _tubulosa_, 105. COLLOSPHÆRIDA, 92. COLLOZOIDA, 23. Collozoum, 24. amoeboides, 28. contortum, 26. coeruleum, 27. discoideum, 27. ellipsoides, 26. inerme, 25. nostochinum, 25. ovatum, 25. pelagicum, 28. serpentinum, 26. stellatum, 28. vermiforme, 27. volvocinum, 25. Conarachnium, 1290. _rayanum_, 1291. _cervus_, 1292. _lophophæna_, 1292. _trochus_, 1290. CONCHARIDA, 1710. Concharium, 1716. bacillarium, 1718. bivalvum, 1717. diatomeum, 1717. fragilissimum, 1718. nucula, 1717. Conchasma, 1718. hibburites, 1719. radiolites, 1719. sphærulites, 1719. CONCHASMIDA, 1716. Conchellium, 1720. hippopus, 1720. tridacna, 1720. Conchidium, 1721. argiope, 1722. dimerella, 1722. leptæna, 1722. magasella, 1723. productum, 1723. rhynchonella, 1722. terebratula, 1721. thecidium, 1721. Conchoceras, 1727. caudatum, 1727. cornutum, 1728. Conchonia, 1723. diodon, 1723. tetrodon, 1724. triodon, 1724. CONCHOPSIDA, 1719. Conchopsis, 1724. aspidium, 1726. carinata, 1725. compressa, 1725. lenticula, 1726. navicula, 1727. orbicularis, 1725. pilidium, 1726. _Conchura_, 1724. _tetrodon_, 1724. Conosphæra, 221. orthoconus, 221. plagioconus, 222. platyconus, 221. Conostrobus, 1469. Cornustrobus, 1470. Cornutanna, 1183. cyrtoconus, 1184. loxoconus, 1184. orthoconus, 1183. Cornutella, 1180. _ampliata_, 1291. annulata, 1182. _bimarginata_, 1295. _cassis_, 1301. circularis, 1181. clathrata, 1182. _cullaris_, 1290. curvata, 1183. distenta, 1181. granulata, 1182. hexagona, 1180. _longiseta_, 1294. mitra, 1181. _obtusa_, 1308. _orthoceras_, 1294. _profunda_, 1284. _pseudoprofunda_, 1762. _pseudoclathrata_, 1762. _quadratella_, 1254. _scalaris_, 1203. sethoconus, 1180. _spiniceps_, 1303. spiralis, 1183. stiligera, 1181. stylophæna, 1182. _trichostyla_, 1294. _trochus_, 1293. _tumens_, 1182. _verrucosa_, 1293. Cornutellium, 1180. Cornutissa, 1181. Cornutosa, 1183. _clathrata_, 1183. Corocalyptra, 1322. agnesæ, 1323. elisabethæ, 1323. emmæ, 1323. ludovicæ, 1324. margarethæ, 1323. COROCYRTIDA, 1129. CORONIDA, 967. Coronidium, 973. acacia, 975. cervicorne, 974. diadema, 974. dyostephanus, 974. Coronophæna, 1178. Coronosphæra, 117. diadema, 117. calycina, 117. convolvulus, 117. Cortina, 950. cervina, 952. conifera, 951. dendroides, 951. furcata, 951. tripus, 950. typus, 951. Cortinetta, 1667. cortiniscus, 1667. tripodiscus, 1667. CORTINIDA, 950. CORTINISCIDA, 963. Cortiniscus, 963. dipylaris, 964. tetrapylaris, 964. tripodiscus, 963. tripylaris, 964. typicus, 964. Corythospyris, 1057. Coscinasparium, 826. Coscinaspidium, 828. Coscinaspis, 826. ceriopora, 826. coscinopora, 826. isopora, 828. orthopora, 827. parmipora, 827. peripora, 825. polypora, 827. rhacopora, 827. stigmopora, 826. Coscinomma, 222. amphisiphon, 222. ectosiphon, 222. endosiphon, 223. macrosiphon, 223. COSCINOMMIDA, 209. _Craniaspis_, 827. _parmipora_, 827. Craspedilium, 1247. _eupilium_, 1247. Craspedomma, 77. CRICOIDEA, 889. Cromyatractus, 335. ceparius, 336. cepicius, 336. tetracelyphus, 335. tetralepus, 335. tetraphractus, 335. Cromyechinus, 263. dodecacanthus, 264. icosacanthus, 263. polyacanthus, 264. Cromyocarpus, 318. quadrifarius, 318. Cromyodruppa, 317. cepa, 317. mango, 318. Cromyodrymus, 264. abietinus, 265. quadricuspis, 264. Cromyomma, 261. circumtextum, 262. macroporum, 262. mucronatum, 263. perplexum, 261. perspicuum, 262. quadruplex, 262. villosum, 261. zonaster, 261. CROMYOMMIDA, 260. Cromyosphæra, 85. antarctica, 85. bigemina, 85. cepa, 85. _perspicua_, 262. quadruplex, 84. rosetta, 84. scorodonium, 85. CROMYOSPHÆRIDA, 84. Cromyostaurus, 167. verticillatus, 167. CROMYOSTYLIDA, 146. Cromyostylus, 147. gladius, 147. Crucidiscus, 415. cruciatus, 416. cuspidatus, 416. echinatus, 416. endostaurus, 416. Cryptocapsa, 1312. bacca, 1313. pila, 1313. Cryptocephalus, 1252. favosus, 1252. _Cryptoprora_, 1252. _microstoma_, 1252. _ornata_, 1375. _plutonis_, 1252. _polyptera_, 1283. Cubaxonium, 204. octahedrum, 204. spongiosum, 204. Cubosphæra, 203. concentrica, 203. cubaxonia, 203. CUBOSPHÆRIDA, 169. CUBOTHOLIDA, 677. Cubotholonium, 682. ellipsoides, 682. sphæroides, 682. Cubotholus, 680. octoceras, 681. quadraticus, 680. regularis, 680. rhombicus, 681. Cycladophora, 1376. campanula, 1379. _davisiana_, 1437. _discoides_, 1397. dodecapleura, 1378. enneapleura, 1378. _erinaceus_, 1383. favosa, 1380. fenestrata, 1390. goetheana, 1375. _gigas_, 1384. hexapleura, 1377. lanterna, 1377. nonagona, 1378. pantheon, 1379. pyramidalis, 1377. spatiosa, 1379. spinosa, 1378. stiligera, 1380. _tabulata_, 1293. tetrapleura, 1376. Cyclampterium, 1371. Cyclamptidium, 1380. CYCLODISCARIA, 409. Cypassis, 366. entomocora, 367. eucolpos, 367. halicora, 368. palliata, 366. puella, 367. Cyphanta, 360. arachnoides, 361. circopora, 361. colpodes, 361. hispida, 362. hystrix, 362. lævis, 361. CYPHINIDA, 359. Cyphinidium, 371. _amphilophus_, 370. amphistylium, 371. apicatum, 371. coronatum, 372. Cyphinoma, 369. Cyphinura, 370. Cyphinus, 369. amphacanthus, 369. amphilophus, 370. dixiphus, 370. penicillatus, 370. Cyphocolpus, 368. didymus, 368. virginis, 369. Cyphonium, 363. diattus, 364. ceratospyris, 366. coscinoides, 363. cribellum, 365. ethmarium, 363. facettarium, 365. hexagonium, 364. mammarium, 364. profundum, 365. trinacrium, 364. virgineum, 363. CYRTELLARIA, 1015. CYRTIDA, 1126. Cyrtidosphæra, 65. _echinoides_, 214. _reticulata_, 66. CYRTOCALPIDA, 1178. Cyrtocalpis, 1185. amphora, 1186. _cassis_, 1301. compacta, 1187. gromia, 1188. lithomitra, 1187. obliqua, 1187. ovulum, 1187. reticulum, 1186. sethopora, 1187. urceolus, 1186. urna, 1186. Cyrtocapsa, 1512. chrysalidium, 1515. colatractus, 1414. compacta, 1512. cornuta, 1513. costata, 1514. diploconus, 1513. fusulus, 1514. incrassata, 1514. inflata, 1513. pyrum, 1513. tetrapera, 1512. Cyrtocapsella, 1512. Cyrtocapsoma, 1514. Cyrtocorys, 1457. CYRTOIDEA, 1126. Cyrtolagena, 1451. _laguncula_, 1451. Cyrtopera, 1450. gasteroptera, 1451. lagenella, 1451. laguncula, 1451. ornithoptera, 1450. thoracoptera, 1450. Cyrtophormis, 1459. aculeata, 1461. acutata, 1461. armata, 1460. cingulata, 1460. cornuta, 1462. corona, 1462. cylindrica, 1461. fimbriata, 1462. ovata, 1460. turricula, 1463. turrita, 1462. Cyrtophormiscus, 1460. Cyrtophormium, 1460. Cyrtostrobus, 1471. Cystidium, 897. inerme, 897. lecythium, 897. princeps, 897. Cystophormis, 1165. aerostatica, 1166. pila, 1165. spiralis, 1166. tabulata, 1166. CYTOPHORA, 1.

Dendrocircus, 948. arborescens, 949. barbadensis, 950. dodecancistra, 949. dodecarrhiza, 949. elegans, 949. quadrangulus, 948. stalactites, 950. Dendrospyris, 1038. arborescens, 1040. bibrachiata, 1039. dirrhiza, 1039. furcata, 1039. polyrrhiza, 1039. ramosa, 1040. stylophora, 1038. Dermatosphæra, 1763. Desmartus, 398. larvalis, 398. tubulatus, 399. Desmocampe, 397. aphrodite, 397. atractus, 398. catenula, 397. tænioides, 397. DESMOCAMPIDA, 392. Desmospyris, 1089. anthocyrtoides, 1090. carpocanium, 1090. cyrtocolpos, 1090. mammillata, 1089. Dicolocapsa, 1312. megacephala, 1312. microcephala, 1312 platycephala, 1312. Dicranastrum, 550. antilope, 551. bifurcatum, 552. cornutum, 551. dichotomum, 550. furcatum, 550. tricuspis, 551. trifarium, 552. wyvillei, 551. Dictyastrella, 524. Dictyastromma, 525. Dictyastrum, 524. aculeatum, 526. angulatum, 524. bandaicum, 525. hexagonum, 525. _lyra_, 538. _taumorphum_, 537. triactis, 526. trirrhopalum, 525. trispinosum, 525. _velatum_, 545. Dictyaspis, 865. compacta, 865. favosa, 865. solidissima, 865. _Dictyatractus_, 1361. _fenestratus_, 1361. Dictyocephalus, 1305. amphora, 1305. ampulla, 1308. australis, 1306. capito, 1309. cavea, 1309. crassiceps, 1306. excellens, 1306. _galeatus_, 1208. globiceps, 1308. hispidus, 1309. _larvatus_, 1292. mediterraneus, 1307. obtusus, 1308. ocellatus, 1306. papillosus, 1307. reticulum, 1307. tabulatus, 1307. urceolus, 1305. Dictyoceras, 1324. bombus, 1325. formica, 1325. insectum, 1324. melitta, 1325. virchowii, 1325. Dictyocha, 1557. _abnormis_, 1561. _abyssorum_, 1559. _aculeata_, 1565. _anacantha_, 1565. _asteroides_, 1564. _binoculus_, 1565. _bipartita_, 1563. _bisternaria_, 1565. _corona_, 1566. _crux_, 1563. _cyrtoides_, 1569. _diadema_, 1567. _diommata_, 1565. _elegans_, 1564. _elliptica_, 1556. epiodon, 1561. _erebi_, 1565. fibula, 1561. _haliomma_, 1565. _hemisphærica_, 1569. _heptacanthus_, 1568. _hexathyra_, 1565. medusa, 1560. _mesophthalma_, 1563. messanensis, 1561. navicula, 1559. _octonaria_, 1566. _ornamentum_, 1565. _pentasterias_, 1564. _polyactis_, 1566. pons, 1559. _ponticulus_, 1559. quadrata, 1559. _quinaria_, 1564. rhombus, 1562. _septenaria_, 1566.. _sirius_, 1566. _speculum_, 1565. stapedia, 1561. _stauracanthus_, 1566. staurodon, 1560. _stella_, 1565. _superstructa_, 1568. _tenella_, 1561. _triacantha_, 1559. _triactis_, 1559. _triangula_, 1555. _trifenestrata_, 1559. trigona, 1764. triommata, 1559. tripyla, 1560. _ubera_, 1565. DICTYOCHIDA, 1554. Dictyocodon, 1334. annasethe, 1334. carolotæ, 1335. palladius, 1335. prometheus, 1336. Dictyocoryne, 592. agrigentina, 593. charybdaea, 593. echinata, 594. euchitonia, 592. pentagona, 593. profunda, 592. tetradiscus, 592. tetras, 597. trigona, 593. Dictyocryphalus, 1308. Dictyomitra, 1476. articulata, 1476. conica, 1477. costata, 1478. demersissima, 1478. ehrenbergii, 1422. eurythorax, 1477. lineata, 1484. macilenta, 1476. microcephala, 1477. multicostata, 1478. polypora, 1477. punctata, 1486. ventricosa, 1503. Dictyomitrella, 1476. Dictyomitrissa, 1477. Dictyomitroma, 1478. Dictyophimium, 1195. Dictyophimus, 1195. arabicus, 1198. bicornis, 1200. brandtii, 1198. bütschlii, 1201. challengeri, 1196. cienkowskii, 1200. cortina, 1197. craticula, 1196. gracilipes, 1197. hamosus, 1199. hertwigii, 1201. lasanum, 1197. longipes, 1197. lucerna, 1199. platycephalus, 1198. plectaniscus, 1196. pocillum, 1200. pyramis, 1196. sphærocephalus, 1195. tridentatus, 1199. tripus, 1195. triserratus, 1200. Dictyoplegma, 90. _spongiosum_, 90. Dictyopodium, 1352. _bicorne_, 1332. _challengeri_, 1231. cothurnatum, 1353. _eucolpum_, 1332. eurylophus, 1352. oxylophus, 1353. scaphopodium, 1353. thyrsolophus, 1354. _trilobum_, 1333. Dictyoprona, 1250. Dictyoprora, 1305. _Dictyosoma_, 90. _spongiosum_, 90. _trigonizon_, 1612. Dictyospyrantha, 1073. Dictyospyrella, 1074. Dictyospyris, 1073. anthophora, 1076. biloba, 1074. _clathrata_, 1049. _clathrus_, 1049. distoma, 1073. enneastoma, 1077. fenestra, 1075. gigas, 1075. hexastoma, 1077. mammillaris, 1076. messanensis, 1076. polystoma, 1077. quadriloba, 1076. _reticulata_, 1096. _sphæra_, 1400. spinulosa, 1075. stalactites, 1073. tetrastoma, 1075. _tridentata_, 1072. triloba, 1074. triomma, 1074. tristoma, 1074. Dictyospyrissa, 1075. Dictyospyromma, 1076. DICYRTIDA, 1192. Didymocyrtis, 364. _ceratospyris_, 366. _entomocora_, 367. _hexagonia_, 364. _faceta_, 365. Didymospyris, 367. _colpodes_, 367. _entomocora_, 367. Dioniscus, 486. Diplactinium, 470. Diplactura, 469. diplobrachia, 469. diploconus, 470. Diplacterium, 469. DIPLOCONIDA, 881. Diploconium, 886. Diploconulus, 885. Diploconus, 885. amalla, 885. cotyliscus, 886. cyathiscus, 885. cylindrus, 885. fasces, 886. hexaphyllus, 886. saturnus, 886. Diplocolpium, 887. Diplocolpulus, 880. Diplocolpus, 887. costatus, 887. cristatus, 887. dentatus, 888. serratus, 888. sulcatus, 888. Diplocyclas, 1392. bicincta, 1393. bicorona, 1392. bizonalis, 1373. DIPLOPHRACTA, 847. Diplosphæra, 246. denticulata, 247. dictyota, 247. gracilis, 247. hexagonalis, 246. ornata, 246. polygonalis, 247. reticulata, 248. _spinosa_, 245. _stellata_, 251. triglochin, 248. DIPLOSPHÆRIDA, 230. DIPLOZONARIA, 640. Dipocoronis, 980. Dipocubus, 993. Diporasparium, 816. DIPORASPIDA, 808. Diporaspidium, 817. Diporaspis, 816. circopora, 816. nephropora, 816. zygopora, 817. DIPOSPYRIDA, 1035. Dipospyris, 1036. bipes, 1036. chelifer, 1037. cubus, 1036. forcipata, 1037. irregularis, 1037. mystax, 1036. sigmopodium, 1037. DISCIDA, 402. DISCOIDEA, 402. DISCOPYLIDA, 571. Discospira, 495. _accrescens_, 499. _bilix_, 496. _deformis_, 498. _duplex_, 497. _helicoides_, 496. _operculina_, 496. _spiralis_, 496. DISCOSPIRIDA, 481. Discopyle, 573. elliptica, 573. osculata, 573. Discozonium, 571. cyclonium, 571. hexagonium, 572. trigonium, 572. Disolenia, 113. Distephanolithis, 970. Distephanus, 1562. aculeatus, 1565. asteroides, 1564. corona, 1566. crux, 1563. diadema, 1567. mesophthalmus, 1563. octogonius, 1567. octonarius, 1566. ornamentum, 1565. pentasterias, 1564. _rotundus_, 1565. sirius, 1566. speculum, 1565. stauracanthus, 1564. Distriactis, 436. alternatus, 437. amphithectus, 437. corallanthus, 437. lirianthus, 436. palmanthus, 437. Dizonium, 635. amphacanthum, 636. circulare, 635. ellipticum, 635. octacanthum, 636. pleuracanthum, 636. stauracanthum, 636. transversum, 635. Dodecaspis, 834. tricinata, 834. trizonia, 835. Doracantha, 756. dorataspis, 756. Doratasparium, 813. DORATASPIDA, 802. Dorataspidium, 814. Dorataspis, 813. _bipennis_, 809. _cataphracta_, 810. _costata_, 812. _diodon_, 837. fusigera, 813. gladiata, 815. loricata, 814. macracantha, 814. macropora, 814. micropora, 815. _parmipora_, 827. _polyancistra_, 840. polypora, 815. typica, 815. _solidissima_, 865. Dorcadospyris, 1040. antilope, 1041. decussata, 1041. dentata, 1040. dinoceras, 1041. lunulata, 1041. Dorypelta, 857. dodecaspis, 858. furcata, 857. gladiata, 857. lithoptera, 858. ramosa, 857. stauroptera, 857. tessaraspis, 858. tetrodon, 857. Dorypeltarium, 856. Dorypeltidium, 857. Dorypeltonium, 858. Druppatractus, 324. accipenser, 325. belone, 325. coronatus, 326. diodon, 327. hippocampus, 324. ichthydium, 324. lævis, 327. pisciculus, 328. ostracion, 326. testudo, 325. xiphias, 327. Druppocarpus, 311. ananassa, 311. borassus, 312. castanea, 311. chamærops, 312. corypha, 312. Druppula, 308. areca, 309. caryota, 309. cocos, 308. drupa, 308. elliptica, 310. nucula, 310. oliva, 310. ovata, 309. pandanus, 308. phoenix, 308. prunum, 310. DRUPPULIDA, 306. Drymosphæra, 248. cladophora, 249. dendrophora, 249. furcata, 249. hexagonalis, 248. polygonalis, 249. Drymospira, 694. DYOPRUNIDA, 288. DYOSPHÆRIDA, 52. DYOSTEPHIDA, 932. Dyscollosphæra, 96. DYSTYMPANIDA, 1006. Dystympanium, 1006. dictyocha, 1007. distephanus, 1007. medusa, 1007.

Echinactura, 480. asteriscus, 480. culcita, 480. goniaster, 480. Echinaspis, 833. diadema, 833. dichotoma, 832. echinoides, 833. Echinocalpis, 1170. Echinocapsa, 1190. ECHINOCYSTIDA, 1. Echinomma, 257. aculeatum, 258. cidaris, 257. diadema, 258. echinidium, 257. sphærechinus, 258. toxopneustes, 259. trinacrium, 258. _Echinosphæra_, 638. _datura_, 638. ECTOLITHIA, lxxii. Elaphococcus, 227. cervicornis, 228. dichotomus, 229. drymodes, 229. elaphoceras, 228. furcatus, 228. umbellatus, 229. umbellifer, 228. Elaphospyris, 1056. alcicornis, 1057. capricornis, 1056. cervicornis, 1057. damæcornis, 1057. heptaceros, 1056. Elatomma, 242. irregulare, 243. juniperinum, 243. penicillus, 243. pinetum, 242. scoparium, 242. ELLIPSIDA, 299. Ellipsidium, 294. artocarpus, 294. datura, 294. echinidium, 295. opuntia, 295. pandanidium, 294. Ellipsostylus, 299. aquila, 300. avicularis, 299. ciconia, 300. columba, 300. gallinula, 301. hirundo, 301. megadictya, 301. ornithoides, 299. psittacus, 300. Ellipsoxiphus, 296. atractus, 298. bipolaris, 287. claviger, 297. elegans, 296. flosculus, 296. fragilis, 296. parvoforaminus, 297. suessi, 297. Ennealacorys, 1374. Enneaphormis, 1246. _rotula_, 1246. _Enneaplegma_, 929. _enneacantha_, 929. Enneapleuris, 1257. Entocannula, 1660. circularis, 1661. hirsuta, 1661. infundibulum, 1661. subglobosa, 1661. ENTOLITHIA, lxxii. Ethmosphæra, 69. conosiphonia, 69. leptosiphonia, 70. macrosiphonia, 70. minuta, 1762. pachysiphonia, 70. polysiphonia, 70. siphonophora, 69. siphonophorites, 1762. stenosiphonia, 70. vulgaris, 1762. ETHMOSPHÆRIDA, 61. Eucecryphalium, 1221. Eucecryphalus, 1220. campanella, 1223. corocalyptra, 1221. cuvieri, 1222. gegenbauri, 1222. halicalyptra, 1221. _huxleyi_, 1215. _lævis_, 1213. mülleri, 1222. _schultzei_, 1216. Euchitonia, 532. acuta, 536. amoena, 1762. beckmannii, 534. carcinus, 535. clathrata, 1762. crevolensis, 1762. cruciata, 533. dubia, 1762. echinata, 536. elegans, 535. _euclidis_, 531. furcata, 532. _gegenbauri_, 439. grandis, 1762. _leydigii_, 530. _koellikeri_, 530. _krohnii_, 539. lanceolata, 434. muelleri, 533. muellerites, 1762. stoehrii, 534. triangulum, 533. virchowii, 535. ypsiloides, 536. zittelii, 534. EUCHITONIDA, 516. Eucollosphæra, 95. EUCORONIDA, 976. Eucoronis, 976. angulata, 978. arborescens, 978. cervicornis, 978. challengeri, 978. lævigata, 977. nephrospyris, 977. perspicillum, 977. EUCYRTIDINA, 1127. Eucyrtidium, 1487. _acanthocephalum_, 1421. _acephalum_, 1484. _acuminatum_, 1488. _acutatum_, 1461. _ægæum_, 1400. _alauda_, 1418. _amplum_, 1402. _ampulla_, 1251. _annulatum_, 1481. _anomalum_, 1492. anthophorum, 1497. _antilope_, 1404. _apiculatum_, 1404. _aquilonare_, 1504. _arctum_, 1414. _argus_, 1472. _armadillo_, 1302. armatum, 1495. _articulatum_, 1476. _asperum_, 1408. _attenuatum_, 1417. _auritum_, 1482. _australe_, 1487. _barbadense_, 1406. _biauritum_, 1411. _bicorne_, 1421. bütschlii, 1492. _campanulatum_, 1400. _cancrinum_, 1299. _carinatum_, 1316. _cassis_, 1424. _cervus_, 1292. chrysalidium, 1490. cienkowskii, 1493. _compactum_, 1512. conostoma, 1495. _cornutella_, 1473. _coronatum_, 1411. _cranoides_, 1322. _crassiceps_, 1306. _creticum_, 1415. _cryptocephalum_, 1426. _cryptoprora_, 1423. _cuspidatum_, 1473. _cylindricum_, 1406. _davisianum_, 1437. _demersissimum_, 1478. _diaphanum_, 1505. doliolum, 1489. ehrenbergii, 1495. _elegans_, 1406. elongatum, 1493. _embolum_, 1369. eruca, 1493. _euporum_, 1502. _excellens_, 1306. _fastosum_, 1369. _ficus_, 1403. _fistuligerum_, 1498. fusiforme, 1489. galatheæ, 1492. galea, 1492. _gemmatum_, 1425. _gracile_, 1295. hertwigii, 1491. _heteroporum_, 1506. hexagonatum, 1489. _hillaby_, 1402. _hispidum_, 1506. _hyperboreum_, 1486. _imbricatum_, 1483. _incrassatum_, 1514. _increscens_, 1506. _infraculeatum_, 1519. lagena, 1491. _lagenoides_, 1498. _lineatum_, 1484. _macilentum_, 1476. _megaloporum_, 1425. _microcephalum_, 1477. _microporum_, 1474. _microtheca_, 1407. _mongolfieri_, 1251. montiparum, 1493. _multiseriatum_, 1505. _nassa_, 1293. _nereidum_, 1502. _nucula_, 1423. _obstipum_, 1484. _ocellatum_, 1306. ovatum, 1495. _pachyderma_, 1483. _papillosum_, 1307. _pauperum_, 1482. _picus_, 1472. _pirum_, 1423. _platycephalum_, 1502. _pleuracanthum_, 1300. profundissimum, 1480. _punctatum_, 1486. _pupa_, 1412. _pusillum_, 1406. _quadrarticulatum_, 1504. _raphanus_, 1498. _reticulum_, 1307. scalarium, 1484. _scolopax_, 1416. _seriolatum_, 1486. _sipho_, 1497. _sphærophilum_, 1418. spinosum, 1490. _stephanophorum_, 1410. stöhrii, 1494. _subacutum_, 1300. teuscheri, 1491. _tornatum_, 1473. _trachelium_, 1405. tricinctum, 1464. _trochus_, 1280. tropezianum, 1488. _tumidulum_, 1506. _turgidulum_, 1415. _versipellis_, 1425. _zancleum_, 1399. _zanguebaricum_, 1400. Eucyrtis, 1488. Eucyrtomphalus, 1221. Euphysetta, 1670. amphicodon, 1670. hybocodon, 1670. staurocodon, 1670. EUPHYSETTIDA, 1666. Euscenarium, 1146. Euscenidium, 1147. Euscenium, 1146. archicyrtis, 1146. furcatum, 1147. hemisphæricum, 1147. plectaniscus, 1146. quadratum, 1148. ramosum, 1148. tricolpium, 1147. tripospyris, 1147. Eusyringium, 1496. cannostoma, 1499. conosiphon, 1496. fistuligerum, 1498. lagenoides, 1498. leptosiphon, 1497. macrosiphon, 1487. pachysiphon, 1496. rhaphanus, 1498. sipho, 1497. siphonostoma, 1499. EUTYMPANIDA, 1007. Eutympanium, 1013. coronarium, 1014. dodecarium, 1014. militare, 1014. musicantum, 1013. octonarium, 1014.

_Flustrella_, 492. _bilobata_, 527. _concentrica_, 492. _cyclia_, 494. _haliomma_, 692. _macropora_, 493. _micromma_, 1761. _spiralis_, 496.

Gamospyris, 1042. annulus, 1042. circulus, 1042. Gazelletta, 1670. bifurca, 1672. cyrtonema, 1671. dendronema, 1674. furcata, 1672. hexanema, 1671. macronema, 1671. melusina, 1674. orthonema, 1671. pectinata, 1672. penicillata, 1672. pinnata, 1672. robusta, 1673. schleinitzii, 1673. studeri, 1673. trispathilla, 1673. GAZELLETTIDA, 1666. Giraffospyris, 1056. _heptaceros_, 1076. Gorgonetta, 1675. bisenaria, 1675. carmarina, 1675. geryonia, 1675. mirabilis, 1674. Gorgospyris, 1069. ehrenbergii, 1070. eurycolpos, 1071. lamellosa, 1071. liriope, 1071. medusa, 1070. medusetta, 1070. polypus, 1070. schizopodia, 1071. thamnopodia, 1071. Gorgospyrium, 1070.

Haeckeliana, 1702. darwiniana, 1702. goetheana, 1702. maxima, 1701. lamarckiana, 1701. murrayana, 1702. porcellana, 1701. HAECKELINIDA, 1700. Hagiastrum, 542. bramæ, 543. buddhæ, 542. christi, 543. _cornutum_, 551. mohammedis, 543. mosis, 543. _rhopalophorum_, 541. Halicapsa, 1189. hystrix, 1191. lithapium, 1190. papillata, 1190. prunoides, 1190. pyriformis, 1191. triglochin, 1190. Halicalyptra, 1168. ampulla, 1169. campanula, 1169. _cancellata_, 1167. castanella, 1170. _cornuta_, 1398. _fimbriata_, 1387. _galea_, 1136. novena, 1169. _orci_, 1397. petalospyris, 1169. _setosa_, 1280. spinosa, 1170. virginica, 1169. HALICALYPTRINA, 1127. Haliomma, 230. _amphiaspis_, 1761. _amphidiscus_, 447. _amphisiphon_, 374. antarcticum, 238. _apertum_, 159. _apiculatum_, 73. arachnium, 230. _asperum_, 344. _asteracanthion_, 196. beroes, 238. boreale, 237. capense, 235. capillaceum, 236. castanea, 232. _cenosphæra_, 291. circumtextum, 233. clavatum, 239. compactum, 239. _contiguum_, 439. _crenatum_, 314. datura, 232. denticulatum, 235. _didymocyrtis_, 366. _didymum_, 367. _dixyphos_, 135. duodecinum, 233. _echinaster_, 240. _echinoides_, 842. _ellipticum_, 310. enneaxiphos, 234. _entactinia_, 74. erinaceum, 236. favosum, 231. _gracile_, 1761. grande, 235. _helianthus_, 446. _hexacanthum_, 184. hexagonium, 230. _hexagonum_, 138. hispidum, 136. horridum, 232. _humboldtii_, 449. _hystrix_, 854. _inerme_, 80. _infundibuliforme_, 72. _lagena_, 527. _lens_, 1761. ligurinum, 1764. lirianthus, 232. longispinum, 235. macrodoras, 238. _medusa_, 80. megaporum, 233. melitomma, 231. _modestum_, 74. _nitidum_, 1761. _oblongum_, 1761. _octacanthum_, 442. _oculatum_, 234. _ovatum_, 309. patagonicum, 239. permagnum, 239. _perspicuum_, 162. _phacodiscus_, 447. _polyacanthum_, 350. _pyriforme_, 1191. _quadruplex_, 262. _radians_, 423. _radiatum_, 423. _radicatum_, 1051. regulare, 231. rhodococcus, 237. _scutum_, 1761. _sexaculeatum_, 186. _sol_, 446. spinulosum, 237. _tabulatum_, 871. tenellum, 236. tenuispinum, 234. _tetracanthum_, 164. _triactis_, 432. _trinacrium_, 254. _triplex_, 314. _umbonatum_, 449. _virginicum_, 1169. wyvillei, 238. Haliommantha, 230. HALIOMMATIDA, 230. _Haliommatidium_, 842. _echinoides_, 842. _fenestratum_, 869. _ligurinum_, 1764. _mülleri_, 871. _tetragonopum_, 845. HALIOMMATINA, 51. Haliommetta, 233. HALIOMMIDA, 230. Haliommilla, 236. Haliommura, 237. Haliphormis, 1166. costata, 1167. lagena, 1167. HAPLOPHRACTA, 847. HAPLOZONARIA, 632. Heliocladus, 451. _dendrophorus_, 451. _furcatus_, 451. Heliodendrum, 452. HELIODISCIDA, 444. Heliodiscus, 444. amphidiscus, 447. apollinis, 450. asteriscus, 445. cingillum, 448. echiniscus, 448. glyphodon, 446. _grottense_, 451. helianthus, 446. humboldti, 449. marginatus, 449. _medusinus_, 438. pertusus, 448. phacodiscus, 447. polymorphus, 447. siculus, 446. simplex, 1762. sol, 446. solaster, 447. sulcatus, 449. trigonodon, 445. trochiscus, 445. umbonatus, 449. zoroaster, 450. Heliodrymus, 450. dendrocyclus, 451. furcatus, 451. grottensis, 451. setosus, 452. ramosus, 452. viminalis, 452. HELIOSESTRIDA, 427. Heliosestrum, 438. ægineta, 440. contiguum, 439. craspedotum, 441. _glyphodon_, 446. irregulare, 440. liriope, 439. medusinum, 438. octagonium, 441. octangulum, 441. octastrum, 438. octonum, 440. quadrigeminum, 439. solarium, 439. Heliosoma, 240. duodecilla, 241. echinaster, 240. elegans, 240. hastatum, 241. indicum, 241. radians, 240. Heliosphæra, 217. actinota, 218. castenella, 219. coronata, 219. cristata, 219. echinoides, 218. echinoidites, 1762. elector, 220. elegans, 218. floribunda, 219. heteracantha, 220. hexagonaria, 217. hyperionis, 220. _inermis_, 62. _insignis_, 212. pectinata, 218. polygonaria, 220. solaris, 221. _tenuissima_, 210. HELIOSPHÆRIDA, 209. Heliostaurus, 434. _cruciatus_, 434. Heliostylus, 429. _dentatus_, 429. _serratus_, 429. _Heptaplegma_, 929. _heptacantha_, 929. HEXACARYIDA, 202. Hexacaryum, 203. arborescens, 203. Hexacolparium, 880. Hexacolpidium, 880. Hexacolpus, 880. conifer, 880. dodecodus, 881. infundibulum, 881. nivalis, 880. trypanon, 881. Hexaconarium, 876. Hexaconidium, 877. Hexacontarium, 200. dentatum, 200. clavatum, 200. HEXACONTIDA, 191. Hexacontium, 192. antarcticum, 197. asteracanthion, 196. axophænum, 196. axotrias, 192. circumtextum, 193. clavigerum, 195. drymodes, 198. favosum, 194. floridum, 195. furcatum, 198. gladiatum, 198. hexaconicum, 196. hexactis, 192. hexagonale, 194. lævigatum, 193. octahedrum, 193. papillosum, 197. periplectum, 199. phænaxonium, 192. polygonale, 197. prionacanthum, 195. sceptrum, 194. setosum, 198. triplosphærium, 193. Hexaconus, 876. ciliatus, 876. coronatus, 877. echinatus, 878. serratus, 877. vaginatus, 877. velatus, 877. Hexacorethra, 1048. _magica_, 1048. Hexacoronis, 981. _Hexacromidium_, 202. _arachnoides_, 202. HEXACROMYIDA, 201. Hexacromyum, 201. arachnoides, 202. _cubaxonium_, 303. elegans, 201. octahedrum, 202. quadrigatum, 201. _Hexactura_, 560. _orchidacea_, 560. Hexadendron, 199. bipinnatum, 200. quadricuspis, 199. Hexadoras, 205. axophæna, 205. lychnosphæra, 205. octahedrum, 205. HEXADORIDA, 205. Hexadoridium, 206. streptacanthum, 206. Hexalacorys, 1372. Hexalasparium, 874. HEXALASPIDA, 872. Hexalaspidium, 875. Hexalaspis, 874. heliodiscus, 875. hexaglypha, 876. hexalastrum, 875. _nivalis_, 880. sexalata, 875. stellata, 875. Hexalastrum, 559. crinanthum, 559. _geryonidum_, 560. orchidaceum, 560. palmanthum, 559. Hexalatractus, 1393. fusiformis, 1394. sexalatus, 1394. Hexaloncharium, 190. hystricinum, 191. octahedrum, 190. philosophicum, 190. Hexalonche, 179. amphisiphon, 182. anaximandri, 182. anaximenis, 183. aristarchi, 185. aspera, 184. brevicornis, 181. castanella, 184. conicornis, 181. cristata, 183. curvicornis, 181. ekphantæa, 185. favosa, 180. geometrica, 184. grandis, 182. heracliti, 187. hexacantha, 184. hystricina, 187. octahedra, 181. octocolpa, 183. phænaxonia, 180. philosophica, 186. pythagoræa, 185. rosetta, 180. seleuci, 186. serrata, 183. setosa, 187. sexaculeata, 186. xenophanis, 187. HEXALONCHIDA, 179. Hexalonchidium, 191. axonometrum, 191. Hexancistra, 188. ancorata, 188. mirabilis, 189. quadricuspis, 189. tricuspis, 188. triserrata, 188. _Hexapitys_, 189. _mirabilis_, 189. Hexaplagia, 915. antarctica, 915. arctica, 915. australis, 916. collaris, 916. HEXAPLAGIDA, 915. Hexaplecta, 927. triaxonia, 927. tricladonia, 927. HEXAPLECTIDA, 927. Hexapleuris, 1257. HEXAPYLIDA, 567. Hexapyle, 568. circularis, 569. dodecantha, 569. hexacantha, 569. polyacantha, 570. sexangula, 568. triacantha, 569. triangula, 568. HEXASPYRIDA, 1046. Hexaspyridium, 1047. Hexaspyris, 1046. alterna, 1047. articulata, 1048. bütschlii, 1047. hexacorethra, 1048. ophirensis, 1048. setigera, 1047. spinosa, 1048. Hexastylarium, 177. elongatum, 178. heteraxonium, 177. quadratum, 178. HEXASTYLIDA, 171. Hexastylidium, 178. rhomboides, 178. spirale, 179. Hexastylus, 171. biantis, 172. brevispinus, 175. chilonis, 174. cleobuli, 174. cochleatus, 174. conifer, 176. contortus, 177. dimensivus, 175. dictyotus, 176. favosus, 172. hirsutus, 176. longispinus, 175. longissimus, 172. marginatus, 176. maximus, 173. minimus, 172. periandri, 173. phænaxonius, 171. pittaci, 173. sapientum, 171. setosus, 174. solonis, 173. spiralis, 177. thaletis, 172. triaxonius, 175. Hexinastrum, 560. geryonidum, 560. Hexonasparium, 878. Hexonaspidium, 879. Hexonaspis, 879. hastata, 879. heliosestrum, 878. hexagona, 879. hexapleura, 879. Hexoniscus, 488. Histiastrum, 544. boseanum, 546. _brunonis_, 548. circulare, 546. coronatum, 546. _democriti_, 548. excisum, 544. _fasciatum_, 535. gladiatum, 545. _lurianense_, 1762. pentadiscus, 546. quadrigatum, 544. quaternarium, 545. _straussii_, 547. _ternarium_, 531. _trinacrium_, 530. velatum, 545. _ypsiloides_, 536. Holosiphonia, 104. HOLOTRYPASTA, 5. Hylaspis, 846. barbata, 847. coronata, 847. serrulata, 846. Hymenactura, 473. archimedis, 473. copernici, 475. hexagona, 474. ptolomaei, 475. pythagoræ, 474. trigona, 474. Hymenactinium, 475. Hymenacturium, 474. Hymenastrella, 530. Hymenastromma, 531. Hymeniastrum, 530. archimedis, 531. euclidis, 531. gümbelii, 530. koellikeri, 530. leydigii, 530. pythagoræ, 531. ternarium, 531. trigonarium, 532. Hystrichasparium, 822. Hystrichaspidium, 823. Hystrichaspis, 822. armata, 824. cristata, 823. divaricata, 824. dorsata, 823. foveolata, 824. fruticata, 825. furcata, 822. pectinata, 822. serrata, 825. sulcata, 824.

ICOSACANTHA, 717. Icosasparium, 843. Icosaspidium, 845. Icosaspis, 844. cruciata, 844. elegans, 844. icosahedra, 845. icosastaura, 846. multiforis, 845. ornata, 844. spectabilis, 845. tabulata, 843. tetragonopa, 845.

Lampoxanthium, 36. _brevispiculum_, 36. octoceras, 37. pandora, 38. punctatum, 37. tetractinium, 37. Lamprocyclas, 1390. ægles, 1391. bajaderæ, 1392. deflorata, 1391. maritalis, 1390. nuptialis, 1390. reginæ, 1391. saltatricis, 1391. Lamprocyclia, 1390. Lamprocycloma, 1392. Lamprodiscus, 1212. coscinodiscus, 1213. lævis, 1214. monoceros, 1213. tricostatus, 1213. Lampromitra, 1214. arborescens, 1216. coronata, 1214. dendrocorona, 1216. furcata, 1215. huxleyi, 1215. pyramidalis, 1215. quadricuspis, 1214. schultzei, 1216. LAMPROSPYRIDA, 1092. Lamprospyris, 1093. darwinii, 1094. hookeri, 1094. huxleyi, 1094. lyelli, 1094. spenceri, 1095. Lamprotripus, 1199. _horridus_, 1201. _spinosus_, 1201. _squarrosus_, 1200. Lampterium, 1376. Lamptidium, 1377. Lamptonium, 1378. LARCARIDA, 605. Larcarium, 608. amphistylum, 608. axostylum, 609. chætostylum, 609. hexastylum, 608. octostylum, 609. polystylum, 609. staurostylum, 608. Larcidium, 611. axacanthum, 611. dissacanthum, 611. dodecanthum, 612. hexacanthum, 611. octacanthum, 612. polyacanthum, 612. LARCOIDEA, 599. Larcospira, 696. lentelliptica, 696. oliva, 697. quadrangula, 696. sexangula, 696. Larcospirema, 696. LARCOSPIRIDA, 695. Larcospironium, 697. LARNACALPIDA, 619. Larnacalpis, 620. lentellipsis, 620. macrococcus, 621. phacodiscus, 620. subsphærica, 621. triaxonia, 621. Larnacantha, 621. bicruciata, 623. cladacantha, 623. decacantha, 624. dissacantha, 622. dodecantha, 624. drymacantha, 624. hexacantha, 622. octacantha, 623. prismatica, 623. quadricornis, 622. stauracantha, 622. LARNACIDA, 614. Larnacidium, 618. hexabelonium, 619. polybelonium, 619. staurobelonium, 619. Larnacilla, 617. medullaris, 618. prometor, 618. subglobosa, 618. typus, 617. LARNACILLIDA, 617. Larnacoma, 625. hexagonium, 625. lentellipticum, 625. quadruplex, 625. Larnacospongus, 626. larnacillifer, 626. tetrapylifer, 626. Larnacostupa, 627. dendrophora, 627. octacantha, 627. spinosa, 627. Leptarachnium, 1248. _aurelia_, 1248. Leptosphæra, 244. ciliata, 245. hexagonalis, 244. polygonalis, 245. reticulum, 246. serrata, 245. spinosa, 245. stellata, 245. Liosphæra, 76. hexagonia, 76. peridromium, 77. polypora, 78. porulosa, 77. rhodococcus, 77. LIOSPHÆRIDA, 59. Liriospyris, 1049. amphithecta, 1050. clathrata, 1049. heteropoda, 1050. hexapoda, 1049. turrita, 1050. Lithapium, 303. halicapsa, 303. monocyrtis, 304. pyriforme, 303. Litharachnium, 1163. arachnodiscus, 1164. araneosum, 1163. discoides, 1164. epeira, 1164. pilidium, 1164. _quadratella_, 1254. tentorium, 1163. Lithatractus, 319. carduelis, 321. cirsium, 321. conifer, 322. conostylus, 323. convallaria, 320. echiniscus, 321. fragilis, 319. gamoporus, 323. hexagonalis, 319. jugatus, 323. leptostylus, 320. lobatus, 322. pachystylus, 320. rosetta, 322. LITHELIDA, 688. Lithelius, 693. alveolina, 694. arborescens, 695. capreolus, 694. primordialis, 694. solaris, 695. spiralis, 693. LITHOBOTRYIDA, 1111. Lithobotrys, 1117. _adspersa_, 1116. _biceps_, 1113. _borealis_, 1116. _cribrosa_, 1113. _denticulata_, 1013. _galea_, 1123. geminata, 1118. _inflata_, 1123. lithocorythium, 1118. mascula, 1119. nasuta, 1118. _nucula_, 1116. orchidea, 1119. ornata, 1118. _quadriloba_, 1109. sphærothorax, 1119. _stiligera_, 1088. _triloba_, 1108. Lithocampe, 1501. _acuminata_, 1488. _ampullacea_, 1402. _anomala_, 1442. aquilonaris, 1504. _arcta_, 1414. _auricula_, 1482. _aurita_, 1482. _australis_, 1487. clava, 1507. _compressa_, 1516. _corbula_, 1761. diaphana, 1505. diploconus, 1505. _eminens_, 1487. eupora, 1502. _fimbriata_, 1462. _fusiformis_, 1503. _galea_, 1492. _heteropora_, 1506. _hexacola_, 1507. _heptacola_, 1506. _hirundo_, 1356. hispida, 1506. _hyperborea_, 1486. _increscens_, 1506. _lagena_, 1491. _lineata_, 1484. meta, 1507. multiseriata, 1505. nereidum, 1502. octocola, 1505. ovata, 1504. platycephala, 1502. polycola, 1508. _punctata_, 1486. quadrarticulata, 1504. radicula, 1503. _seriolata_, 1486. _sinuosa_, 1761. _solitaria_, 1281. _subligata_, 1518. _tropeziana_, 1488. tumidula, 1506. urceolata, 1507. ventricosa, 1503. LITHOCAMPIDA, 1467. Lithocampium, 1504. _eurythorax_, 1474. Lithocampula, 1502. _Lithocarpium_, 1172. _pyriforme_, 1172. Lithochytridium, 1363. LITHOCHYTRINA, 1127. Lithochytris, 1362. _barbadensis_, 1239. cortina, 1362. galeata, 1363. lanterna, 1364. lucerna, 1364. pileata, 1363. pteropus, 1364. pyramidalis, 1364. pyriformis, 1362. _triangula_, 1240. tripodium, 1363. vespertilio, 1365. Lithochytrodes, 1362. LITHOCIRCIDA, 940. Lithocircus, 943. annularis, 943. _annulus_, 1761. crambessa, 944. decimalis, 944. furcatus, 945. haeckelii, 1762. hexablastus, 944. magnificus, 945. _mesocena_, 132. _productus_, 948. quadricornis, 944. rhombus, 1762. tarandus, 944. _triangularis_, 1555. truncatus, 1762. _vinculatus_, 975. Lithocoronis, 978. _challengeri_, 978. _Lithocorythium_, 1117. _cephalodes_, 978. _galea_, 1123. _oxylophus_, 1118. _platylophus_, 1118. Lithocubus, 1011. astragalus, 1012. geometricus, 1011. octacanthus, 1011. vinculatus, 1012. Lithocyclia, 459. cingulata, 459. heteropora, 460. lenticula, 459. monococcus, 460. ocellus, 460. _reticulata_, 1761. _stella_, 467. LITHOCYCLIDA, 459. LITHOCYCLIDINA, 455. Lithogromia, 1647. diatomacea, 1647. lenticula, 1647. silicea, 1647. LITHOGROMIDA, 1647. Litholopharium, 735. LITHOLOPHIDA, 733. Litholophidium, 735. Litholophonium, 736. Litholophus, 734. decapristis, 735. decastylus, 735. decimalis, 735. fasciculus, 736. ligurinus, 736. penicillus, 736. pyramidalis, 735. rhipidium, 736. Lithomelissa, 1203. amphora, 1205. bicornis, 1206. bütschlii, 1207. _capito_, 1257. corythium, 1207. decacantha, 1208. ehrenbergii, 1204. _falcifera_, 1207. haeckelii, 1207. _hertwigii_, 1207. macroceros, 1204. macroptera, 1204. mediterranea, 1206. _microptera_, 1236. microstoma, 1205. mitra, 1204. pycnoptera, 1205. _spongiosa_, 1210. thoracites, 1206. _ventricosa_, 1236. Lithomespilus, 301. _alauda_, 128. flammabundus, 303. flammeus, 302. phloginus, 302. phlogoides, 302. _picus_, 129. _trogon_, 129. Lithomitra, 1483. acephala, 1484. australis, 1487. chrysalis, 1485. costata, 1485. cylindrica, 1485. eminens, 1487. eruca, 1485. hyperborea, 1486. infundibulum, 1487. lineata, 1484. nodosaria, 1484. pachyderma, 1482. punctata, 1486. seriolata, 1486. Lithomitrella, 1483. Lithomitrissa, 1485. Lithopera, 1233. _amblystauros_, 1311. ananassa, 1234. bacca, 1233. bursella, 1234. _denticulata_, 1073. elongata, 1762. globosa, 1234. gutta, 1234. _lagena_, 1233. _nidus_, 1311. _oceania_, 1232. ovata, 1762. _oxystauros_, 1311. _pyrum_, 1232. _setosa_, 1276. Lithophyllium, 753. condylatum, 754. cruciatum, 754. foliosum, 754. gladiatum, 754. Lithoptera, 778. darwinii, 781. dodecaptera, 780. fenestrata, 781. icosaptera, 781. lamarckii, 779. mülleri, 779. quadrata, 780. tetragona, 780. tetraptera, 779. Lithopteranna, 779. Lithopterella, 780. LITHOPTERIDA, 776. Lithopteroma, 780. Lithornithium, 1354. ciconia, 1354. _dictyoceras_, 1325. falco, 1355. foveolatum, 1355. fringilla, 1355. hirundo, 1356. _loxia_, 1452. _luscinia_, 1358. trochilus, 1355. Lithospira, 693. Lithostrobus, 1468. acuminatus, 1472. argus, 1472. botryocyrtis, 1475. caloceras, 1471. conulus, 1472. cornutus, 1474. cornutella, 1473. cuspidatus, 1473. cyrtoceras, 1470. distichus, 1469. hexagonalis, 1475. hexastichus, 1470. leptoceras, 1471. lithobotrys, 1475. macroceras, 1471. microporus, 1474. monostichus, 1469. pentastichus, 1470. picus, 1472. quadratus, 1474. seriatus, 1474. tetrastichus, 1470. tornatus, 1473. tristichus, 1469. Lithotympanum, 1006. spinosum, 1006. tuberosum, 1006. Lonchostaurus, 772. bifidus, 773. bifurcus, 773. crystallinus, 773. lanceolatus, 773. rhombicus, 773. rhomboides, 772. Lophoconus, 1403. antilope, 1404. apiculatus, 1404. cervus, 1405. cornutella, 1404. hexagonalis, 1404. rhinoceros, 1405. Lophocorys, 1420. acanthocephala, 1421. astrocephala, 1421. bicornis, 1421. brevicornis, 1422. quadricornis, 1422. Lophocyrtis, 1410. biaurita, 1411. coronata, 1411. holothuria, 1410. stephanophora, 1410. synapta, 1411. Lophophæna, 1303. _amphora_, 1302. _apiculata_, 1303. _capito_, 1204. circumtexta, 1304. _cornuta_, 1398. echinocephala, 1304. galea, 1303. galeata, 1204. _larvata_, 1282. liothorax, 1304. _lynx_, 1303. _obtusa_, 1308. radians, 1303. Lophophænoma, 1304. Lophophænula, 1303. LOPHOSPYRIDA, 1078. Lophospyris, 1066. acuminata, 1080. comosa, 1071. dipodiacus, 1080. Lychnasparium, 839. LYCHNASPIDA, 835. Lychnaspidium, 842. _haliommidium_, 842. Lychnaspis, 829. capillaris, 839. cataplasta, 843. echinoides, 842. giltschii, 839. haliommidium, 842. longissima, 841. maxima, 839. minima, 841. polyancistra, 840. rabbeana, 842. rottenburgii, 841. serrata, 840. undulata, 841. wagenschieberi, 840. Lychnocanella, 1224. Lychnocanissa, 1225. Lychnocanium, 1224. _arabicum_, 1198. _campanella_, 1331. carinatum, 1226. clavigerum, 1230. continuum, 1225. crassipes, 1230. cypselus, 1229. _depressum_, 1331. falciferum, 1207. favosum, 1225. fenestratum, 1228. fortipes, 1227. _hamosum_, 1199. hirundo, 1227. lanterna, 1224. _lucerna_, 1199. nodosum, 1225. ovatum, 1229. _prætextum_, 1330. pudicum, 1230. pyriforme, 1225. sigmopodium, 1228. _tetrapodium_, 1228. tribulus, 1226. trichopus, 1228. _tridentatum_, 1199. tripodium, 1229. tuberosum, 1227. _turgidum_, 1319. ventricosum, 1226. Lychnocanoma, 1229. Lychnodictyum, 1230. challengeri, 1231. sethopodium, 1231. scaphopodium, 1231. wyvillei, 1231. Lychnosphæra, 276. regina, 277. _rhizoplegma_, 276.

Mazosphæra, 108. apicata, 109. hippotis, 108. _inflata_, 101. lævis, 109. lagotis, 108. Medusetta, 1667. codonium, 1668. craspedota, 1669. minima, 1668. quadrigata, 1668. spiralis, 1669. tetranema, 1669. tiara, 1668. MEDUSETTIDA, 1663. Melitomma, 76. formosum, 231. _melittosphæra_, 73. Melittosphæra, 72. Merosiphonia, 106. MEROTRYPASTA, 5. Mesocena, 1554. annulus, 1555. _binonaria_, 1557. bisoctona, 1557. circulus, 1555. _crenulata_, 1555. diodon, 1555. elliptica, 1556. _heptagona_, 1557. hexagona, 1556. _nonaria_, 1557. octogona, 1557. _octoradiata_, 1557. pentagona, 1556. quadrangula, 1556. _quaternaria_, 1556. _senaria_, 1556. _septenaria_, 1556. stellata, 1557. triangula, 1555. Microcubus, 997. amphispyris, 999. cornutus, 999. dodecastoma, 998. pentacircus, 998. quadrupes, 998. zonarius, 998. Micromelissa, 1205. apis, 1235. bombus, 1235. microptera, 1236. ventricosa, 1236. vespa, 1235. Mitrocalpis, 1188. palliata, 1188. MONOCYRTIDA, 1133. MONODICTYA, 1126. MONOPRUNIDA, 288. MONOPYLARIA, 889. MONOPYLEA, 889. MONOSPHÆRIDA, 52. MONOSTEPHIDA, 937. Monostephus, 940. Monozonium, 633. alatum, 633. amphistylum, 634. hartingii, 1763. pleurostylum, 634. primordiale, 633. staurostylum, 634. Myelastrella, 553. Myelastromma, 553. Myelastrum, 553. anomalum, 556. ciliatum, 555. decaceros, 554. dodecaceros, 554. farfalla, 554. giganteum, 555. heteropterum, 553. lobatum, 555. medullare, 553. octocorne, 553. papilio, 554. rotula, 555. spinale, 553. _Myxobrachia_, 22. _cienkowskii_, 1763. _pluteus_, 22. _rhopalum_, 22.

Nassella, 898. nassiterna, 898. thalassicolla, 898. NASSELLARIA, 889. NASSELLIDA, 896. NASSOIDEA, 895. Nephrodictyum, 1101. NEPHROSPYRIDA, 1099. Nephrospyris, 1100. cordata, 1102. nephridium, 1101. paradictyum, 1102. paradoxa, 1102. phaseolus, 1101. renilla, 1101.

Octalacorys, 1373. Octodendron, 279. araucaria, 280. arboretum, 281. contortum, 281. cubocentron, 279. pinetum, 280. spathillatum, 280. spirale, 279. verticillatum, 281. Octopelta, 855. cultella, 855. furcella, 856. scutella, 856. Octophormis, 1245. Octopyle, 650. amphistyle, 651. decastyle, 654. euryzona, 652. hexastyle, 653. obtecta, 653. octostyle, 653. ovulina, 650. quadrata, 650. sexangulata, 653. staurostyle, 651. stenozona, 652. subglobosa, 651. tetraptera, 652. tetrastyle, 652. transversaria, 651. Octotympanum, 999. arborescens, 1000. cervicorne, 1000. octonarium, 1000. octospinum, 1000. Odontosphæra, 102. cyrtodon, 102. monodon, 102. OMMACAMPIDA, 392. Ommatartus, 396. amphicanna, 396. amphisiphon, 396. amphiobolus, 396. Ommathymenium, 520. OMMATIDA, 51. Ommatocampe, 393. amphilonche, 395. annulata, 393. chætopodum, 395. erucæformis, 394. increscens, 393. nereis, 394. polyarthra, 393. _profundissima_, 380. _setosa_, 381. Ommatocyrtis, 366. OMMATODISCIDA, 500. Ommatodiscus, 500. circularis, 501. decipiens, 500. fragilis, 502. haeckelii, 501. lævigatus, 502. stöhrii, 501. _Ommatogramma_, 519. _navicularis_, 519. _Ommatospyris_, 363. _apicata_, 371. _coscinoides_, 363. _entomocora_, 367. _ethmaria_, 363. _loeevis_, 361. _penicillata_, 370. _profunda_, 365. _virginea_, 363. Orodendrum, 1598. Orodictyum, 1601. Orona, 1594. crassissima, 1594. maxima, 1594. robusta, 1594. ORONIDA, 1593. Oronium, 1594. Orophasparium, 818. Orophaspidium, 818. Orophaspis, 817. astrolonche, 818. diporaspis, 819. furcata, 818. gladiata, 818. ramosa, 818. tessaraspis, 819. Oroplegma, 1600. diplosphæra, 1600. giganteum, 1601. spinulosum, 1600. spongiosum, 1601. velatum, 1600. Oroplegmium, 1600. Oroscena, 1597. bærii, 1598. cuvieri, 1598. darwinii, 1599. duncanii, 1599. gegenbauri, 1597. huxleyi, 1599. mülleri, 1598. wolffii, 1598. OROSCENIDA, 1593. Oroscenium, 1597. Orosphæra, 1594. arborescens, 1597. clavigera, 1596. confluens, 1596. foveolata, 1595. furcata, 1596. fusigera, 1595. hastigera, 1595. horrida, 1596. ramigera, 1596. spinigera, 1595. serpentina, 1595. OROSPHÆRIDA, 1590. Orothamnus, 1596. _arborescens_, 1597. Otosphæra, 116. auriculata, 116. polymorpha, 116.

PANACANTHA, 715. Panarium, 388. annularium, 389. artophorum, 389. facettarium, 388. pipettarium, 389. tubularium, 390. Panartella, 377. PANARTIDA, 375. Panartissa, 379. Panartoma, 381. Panartura, 381. Panartus, 376. amphiconus, 379. diploconus, 379. fusiformis, 379. pluteus, 382. profundissimus, 380. quadriceps, 380. quadrigeminus, 381. quadrijugus, 380. setosus, 381. spinosus, 381. tetracolus, 377. tetrameres, 378. tetraphalangus, 378. tetraplus, 377. tetrathalamus, 378. Panicium, 385. amphacanthum, 385. amphistylus, 385. coronatum, 386. scoparium, 385. PANSOLENIA, 1521. Pantopelta, 855. icosaspis, 855. PARADICTYIDA, 1099. Paradictyum, 1102. paradoxum, 1102. Parastephanus, 1008. asymmetricus, 1008. circularis, 1008. dispar, 1009. quadrispinus, 1008. PARASTEPHIDA, 987. PARATYMPANIDA, 1004. Paratympanum, 1005. decastylum, 1005. hexastylum, 1005. octostylum, 1005. Patagospyris, 1087. anthocyrtis, 1088. confluens, 1088. lanceolata, 1088. stiligera, 1088. PELTOPHRACTA, 803. Pentactura, 479. astropecten, 479. pentactis, 479. Pentalacorys, 1371. Pentalastrum, 556. asteracanthion, 556. astropecten, 556. cometa, 557. ophidiaster, 557. Pentaphormis, 1244. _Pentaplegma_, 930. _decacantha_, 930. Pentasolenia, 113. PENTASPYRIDA, 1052. Pentaspyris, 1054. isacantha, 1055. pentacantha, 1054. Pentinastrum, 557. asteriscus, 557. goniaster, 558. Pentoniscus, 488. Pentophiastrum, 558. caudatum, 559. dicranastrum, 558. forcipatum, 559. Periarachnium, 1297. periplectum, 1297. Perichlamydium, 499. accrescens, 499. _æquale_, 515. _asteriscus_, 514. _limbatum_, 514. prætextum, 499. saturnus, 499. spirale, 499. _spongiosum_, 516. _venustum_, 515. Peridarium, 1153. Peridium, 1153. alatum, 1155. cervinum, 1155. curvipes, 1154. lasanum, 1154. palmipes, 1154. papillatum, 1154. spinipes, 1154. Peripanarium, 390. cenoconicum, 390. cenocylindricum, 391. Peripanartus, 382. amphiconus, 383. _amphicorona_, 387. atractus, 384. cylindrus, 384. lævigatus, 383. palliatus, 382. Peripanicium, 386. amphicorona, 387. amphixiphus, 386. coronarium, 387. Periphæna, 426. cincta, 426. decora, 426. statoblastus, 426. Periplecta, 926. cortina, 926. monocyrtis, 927. pteroscenium, 926. PERIPYLARIA, 6. PERIPYLEA, 6. Peripyramis, 1162. cirumtexta, 1162. spongiosa, 1162. Perispira, 494. _perforata_, 495. _radiata_, 495. _Perispongidium_, 498. _irregulare_, 498. PERISPYRIDA, 1095. Perispyris, 1098. bicincta, 1099. lentellipsis, 1099. spongiosa, 1099. Perizona, 427. scutella, 427. pterygota, 427. Peromelissa, 1236. calva, 1237. capito, 1237. phalacra, 1236. psilocrana, 1237. Petalospyrantha, 1060. Petalospyrella, 1060. Petalospyris, 1059. anthemis, 1062. anthocyrtoides, 1090. _arachnoides_, 1065. argiscus, 1062. bellidiastrum, 1063. _carinata_, 1074. _clathrus_, 1049. _confluens_, 1088. corona, 1061. _diaboliscus_, 1065. dictyocubus, 1063. dinoceras, 1063. eupetala, 1061. _flabellum_, 1174. floscula, 1060. foveolata, 1060. furcata, 1064. lobata, 1064. novena, 1062. _ocellata_, 1174. octopus, 1061. _ophirensis_, 1048. papillata, 1063. _pentas_, 1070. platyacantha, 1060. _radicata_, 1051. _seminulum_, 1046. _spinosa_, 1048. tessaromma, 1062. triomma, 1060. Petalospyrissa, 1061. Petalospyromma, 1062. PHACODISCARIA, 409. PHACODISCIDA, 419. Phacodiscus, 424. clypeus, 425. echiniscus, 425. grandis, 425. lentiformis, 425. rotula, 424. Phacostaurium, 435. Phacostaurus, 435. magnificus, 436. oceanidum, 435. _pyramidalis_, 465. quadrigatus, 436. Phacostylium, 430. Phacostylus, 430. amphipyramis, 431. amphistylus, 430. amphixiphos, 430. caudatus, 431. maximus, 431. PHÆNOCALPIDA, 1157. Phænocalpis, 1173. carinata, 1174. flabellum, 1174. ocellata, 1174. petalospyris, 1173. Phænoscenium, 1174. cladopodium, 1175. hexapodium, 1175. polypodium, 1175. Phæocolla, 1544. primordialis, 1544. PHÆOCONCHIA, 1710. PHÆOCOSCINA, 1537. PHÆOCYSTINA, 1542. PHÆODARIA, 1521. Phæodina, 1545. cannopylea, 1546. tripylea, 1545. PHÆODINIDA, 1543. PHÆOGROMIA, 1642. PHÆOSPHÆRIA, 1590. Pharyngella, 1662. gastræa, 1662. gastrula, 1662. invaginata, 1662. monoceros, 1662. PHARYNGELLIDA, 1660. Pharyngosphæra, 98. stomodæa, 98. Phatnacantha, 765. icosaspis, 765. tessaraspis, 765. Phatnasparium, 868. PHATNASPIDA, 861. Phatnaspidium, 871. Phatnaspis, 870. coscinoides, 870. cristata, 869. ensiformis, 869. fenestrata, 869. haliommidium, 871. lacunaria, 869. loculata, 869. mülleri, 871. orthopora, 870, polypora, 870. quadratura, 871. tabulata, 871. Phatnasplenium, 870. Phlebarachnium, 1295. _facetum_, 1296. _setosum_, 1296. _venosum_, 1297. Phoenicosphæra, 75. Phormobotrys, 1124. cannothalamia, 1125. hexathalamia, 1125. pentathalamia, 1124. polythalamia, 1125. trithalamia, 1124. Phormocampe, 1456. campanula, 1456. conus, 1458. eucalyptra, 1457. lamprocyclas, 1457. metalis, 1457. mitra, 1458. PHORMOCAMPIDA, 1453. PHORMOCYRTIDA, 1365. Phormocyrtis, 1368. carinata, 1368. costata, 1369. embolum, 1369. fastosa, 1369. longicornis, 1370. quadrata, 1369. Phormosphæra, 61. PHORMOSPYRIDA, 1084. Phormospyris, 1076. tricostata, 1087. tridentata, 1087. trifoliata, 1087. PHORTICIDA, 708. Phorticium, 709. abnorme, 710. deforme, 710. pylonium, 709. spironium, 709. Phortolarcus, 710. Phortopyle, 709. Phractacantha, 755. bifurca, 755. bipennis, 755. PHRACTACANTHIDA, 753. Phractasparium, 808. PHRACTASPIDA, 808. Phractaspidium, 810. Phractaspis, 809. bipennis, 809. cataphracta, 810. complanata, 809. condylophora, 809. constricta, 810. prototypus, 809. Phractasplenium, 809. bipenne, 809. Phractopelta, 852. aspidomma, 854. dorataspis, 852. diporaspis, 852. dyadopora, 852. haliomma, 854. hexadopora, 853. hystrix, 854. octadopora, 853. tessaraspis, 853. tessaromma, 854. tetradopora, 853. PHRACTOPELTIDA, 847. Phrenocodon, 1433. clathrostomium, 1434. diaphragma, 1434. Phyllostaurus, 744. Physematium, 34. atlanticum, 35. mülleri, 35. PILOCYRTIDA, 1129. Pipetta, 337. conus, 338. fusus, 337. salpinx, 338. tuba, 337. Pipettaria, 339. fusaria, 339. tubaria, 339. Pipettella, 304. elongata, 305. fusiformis, 304. prismatica, 305. tubulosa, 305. Pityomma, 259. drymodes, 260. piniferum, 260. scoparium, 259. Plagiacantha, 909. abietina, 910. arachnoides, 910. dodecantha, 910. elatine, 911. furcata, 910. verticillata, 910. PLAGIACANTHIDA, 898. Plagiocarpa, 914. procortina, 914. procyrtella, 914. PLAGONIDA, 906. Plagonidium, 913. bigeminum, 913. quadrigeminum, 914. Plagoniscus, 912. cortinaris, 913. euscenium, 912. nassellaris, 913. tripodiscus, 912. Plagonium, 916. arborescens, 917. distriactis, 917. lampoxanthium, 907. sphærozoum, 916. trigeminum, 917. _Platybursa_, 1051. _compressa_, 1051. _Platycryphalus_, 1298. _sethodiscus_, 1298. PLECTANIDA, 919. Plectaniscus, 924. archiscenium, 925. cladoscenium, 925. clathrocorys, 925. cortiniscus, 925. tripodiscus, 925. Plectanium, 928. ovodimare, 928. sphærozoum, 928. trigeminum, 928. PLECTELLARIA, 895. PLECTIDA, 898. Plectocoronis, 979. anacantha, 979. pentacantha, 979. triacantha, 979. PLECTOIDEA, 898. Plectophora, 922. arachnoides, 922. novena, 923. pyramidalis, 923. triomma, 922. Plectopyramis, 1256. dodecomma, 1258. fenestrata, 1259. furcata, 1259. heteromma, 1259. hexapleura, 1257. lagena, 1260. magnifica, 1257. polygonomma, 1258. polypleura, 1260. quadratomma, 1258. serrata, 1259. _spongiosa_, 1261. trapezomma, 1258. Plegmosphæra, 87. coelopila, 88. entodictyon, 88. exodictyon, 89. leptodictyon, 89. leptoplegma, 89. maxima, 88. pachypila, 88. pachyplegma, 89. _polybrocha_, 930. PLEGMOSPHÆRIDA, 86. Pleurasparium, 811. Pleuraspidium, 812. Pleuraspis, 811. amphithecta, 811. costata, 812. horrida, 811. pyramidalis, 812. ramosa, 812. Pleuropodium, 1336. charybdeum, 1336. cortina, 1336. Podocampe, 1445. conica, 1446. cornuta, 1446. trictenota, 1446. tripodiscus, 1446. PODOCAMPIDA, 1435. Podocoronis, 980. cortiniscus, 981. dipodiscus, 980. hexapodiscus, 982. petalospyris, 982. polypodiscus, 982. tetrapodiscus, 981. toxarium, 980. tripodiscus, 981. Podocyrtarium, 1337. Podocyrtecium, 1339. PODOCYRTIDA, 1314. Podocyrtidium, 1344. Podocyrtis, 1337. _aculeata_, 1373. _ægles_, 1391. _aerostatica_, 1252. _amphiacantha_, 1344. ampla, 1348. argulus, 1344. argus, 1346. attenuata, 1338. _bicornis_, 1349. brevipes, 1340. bromia, 1349. _campanella_, 1331. centriscus, 1341. _charybdea_, 1336. collaris, 1340. conica, 1338. conulus, 1339. corythæola, 1339. costata, 1345. _cothurnata_, 1353. cristata, 1342. _dipus_, 1349. divergens, 1340. _domina_, 1387. ehrenbergii, 1344. euceros, 1342. eulophos, 1346. favosa, 1346. floribunda, 1347. flosculata, 1341. fusiformis, 1346. hexagonalis, 1343. lithoconus, 1348. lyæa, 1348. magnifica, 1341. _micracantha_, 1761. mitra, 1345. mitrella, 1345. nana, 1348. ovata, 1343. papalis, 1344. _parvipes_, 1371. pedicellaria, 1347. _pentacantha_, 1371. princeps, 1342. prismatica, 1340. _puella_, 1387. _radicata_, 1351. _rhizodon_, 1351. scaphopodia, 1347. schomburgkii, 1343. sinuosa, 1347. sphærogaster, 1349. _spinosa_, 1169. surena, 1339. tetracantha, 1371. thyrsoceras, 1338. triacantha, 1350. tridactyla, 1339. tripodiscus, 1338. tripus, 1349. urceolata, 1343. ventricosa, 1347. Podocyrtonium, 1347. Polyalacorys, 1374. POLYCYRTIDA, 1103. POLYCYSTINA, 1. Polyplagia, 917, duodenaria, 918. novenaria, 918. octonaria, 918. septenaria, 918. viminaria, 919. POLYPLAGIDA, 917. Polyplecta, 929. decacantha, 930. dumetum, 930. enneacantha, 929. heptacantha, 928. polybrocha, 930. POLYPLECTIDA, 929. Polypleuris, 1260. Polypetta, 1676. alveolata, 1676. mammillata, 1677. polynema, 1676. tabulata, 1677. POLYPRUNIDA, 288. Polysolenia, 113. _setosa_, 100. POLYSPHÆRIDA, 52. POLYSPYRIDA, 1059. Polystichia, 1762. ehrenbergii, 1762. haeckelii, 1762. muelleri, 1762. Porcupinia, 1663. aculeata, 1663. cordiformis, 1663. Porocapsa, 800. coronodon, 801. murrayana, 800. octodon, 800. tetrodon, 800. POROCAPSIDA, 799. PORODISCIDA, 481. Porodiscus, 491. bispiralis, 497. bilix, 496. centrospira, 495. concentricus, 492. deformis, 498. duplex, 497. ellipticus, 494. flustrella, 493. helicoides, 496. heterocyclus, 494. irregularis, 498. macroporus, 493. microporus, 493. operculina, 496. orbiculatus, 492. perispira, 495. quadrigatus, 494. radiatus, 495. semispiralis, 497. sorites, 493. spiralis, 496. _Porospathis_, 1677. _mammillata_, 1677. _tubulata_, 1677. Porosphæra, 67. Prismatium, 1009. tripleurum, 1010. tripodium, 1009. Pristacantha, 765. dodecodon, 766. octodon, 765. polyodon, 766. Pristodiscus, 418. Procyttarium, 13. _primordiale_, 13. PROTYMPANIDA, 991. Protympanium, 991. amphipodium, 992. primordiale, 991. trissocircus, 992. Prunocarpus, 316. artocarpium, 316. datura, 316. melocactus, 317. sparganium, 316. PRUNOIDEA, 284. PRUNOPHRACTA, 859. Prunosphæra, 74. Prunulum, 313. amygdalum, 313. cerasum, 313. coccymelium, 313. crenatum, 314. fenestratum, 315. frugulum, 313. persicum, 314. pyrenium, 315. triplex, 314. Pseudocubus, 1010. hexapylus, 1011. obeliscus, 1010. octostylus, 1010. Psilomelissa, 1208. calvata, 1209. galeata, 1208. hertwigii, 1209. phalacra, 1208. sphærocephala, 1209. Pteractis, 535. _elegans_, 535. Pterocanarium, 1329. Pterocanidium, 1332. Pterocanium, 1328. _barbadense_, 1318. _bibrachiatum_, 1327. bicorne, 1332. _bombus_, 1443. campanella, 1331. _charybdeum_, 1336. contiguum, 1330. _davisianum_, 1437. depressum, 1331. eucolpum, 1332. _falciferum_, 1317. gravidum, 1329. orcinum, 1329. prætextum, 1330. proserpinæ, 1329. pyramis, 1330. _sabæ_, 1317. _sphinx_, 1443. tricolpum, 1331. trilobum, 1333. virgineum, 1330. Pterocodon, 1333. _apis_, 1318. campana, 1333. _campanella_, 1223. _davisianus_, 1437. favosus, 1334. ornatus, 1333. Pterocorys, 1316. apis, 1318. aquila, 1317. barbadensis, 1318. campanula, 1316. carinata, 1316. columba, 1317. falcifera, 1317. hirundo, 1318. macroptera, 1321. melitta, 1319. pipetta, 1320. prismatica, 1320. rhinoceros, 1320. sabæ, 1317. tricornis, 1320. tubulosa, 1319. turgida, 1319. zittelii, 1321. Pterocorythium, 1320. _Pterocyrtidium_, 1316. _barbadense_, 1318. _zittelii_, 1321. Pteropilium, 1326. bombus, 1443. clathrocanium, 1327. eques, 1327. hoplites, 1327. pyramis, 1443. sphinx, 1443. stratiotes, 1326. Pteroscenium, 1151. arcadophorum, 1152. arcuatum, 1152. macropodium, 1153. pinnatum, 1152. spinulosum, 1152. tripocolpum, 1153. _Pterosyringium_, 1319. _tubulosum_, 1319. PYLOBOTRYIDA, 1119. Pylobotrys, 1121. cerebralis, 1122. fontinalis, 1122. putealis, 1121. PYLODISCIDA, 561. Pylodiscus, 570. cardiopylus, 571. nephropylus, 571. sexangularis, 570. triangularis, 570. Pylolena, 568. inermis, 568. armata, 568. PYLONIDA, 628. Pylonium, 654. circozonium, 654. hexazonium, 655. nephropylium, 655. octacanthum, 655. quadricorne, 655. stenozonium, 656. Pylospira, 697. tetrapyle, 698. octopyle, 698. cymbium, 698. Pylospirema, 697. PYLOSPYRIDA, 1078. Pylospyris, 1083. canariensis, 1084. denticulata, 1083. trinacria, 1083. Pylospironium, 698. Pylozonium, 659. novemcinctum, 659. octacanthum, 660.

Quadriloncharium, 776. QUADRILONCHIDA, 766. Quadrilonchidium, 777. Quadrilonche, 776. mesostaura, 777. platystaura, 777. telostaura, 777. tetrastaura, 776.

Rhaphidocapsa, 211. Rhaphidococcus, 210. _acufer_, 211. _lurianensis_, 1762. _simplex_, 216. Rhaphidodrymus, 214. Rhaphidosphæra, 214. _reticulata_, 217. Rhaphidozoum, 46. acuferum, 46. arachnoides, 47. ascensionis, 48. asperum, 47. australe, 48. capense, 48. neapolitanum, 47. pacificum, 46. pandora, 49. patagonicum, 48. pelagicum, 46. polymorphum, 49. Rhizoplegma, 275. lychnosphæra, 275. polyacanthum, 275. radicatum, 276. spirale, 275. trigonacanthum, 276. Rhizosphæra, 283. leptomita, 284. serrata, 284. trigonacantha, 283. Rhodosphæra, 83. hexagonia, 83. melitomma, 83. palliata, 83. pentaphylla, 83. RHODOSPYRIDA, 1087. Rhodospyris, 1088. triceros, 1089. tricornis, 1089. Rhopalastrella, 526. Rhopalastromma, 528. Rhopalastrum, 526. arcticum, 529. _bandaicum_, 525. clavatum, 528. hexaceros, 529. _hexagonum_, 525. irregulare, 528. lagenosum, 527. malleus, 527. martellum, 528. pistillum, 527. triceros, 529. _trispinosum_, 525. truncatum, 526. ypsilinum, 528. Rhopalatractus, 1360. fenestratus, 1361. foveolatus, 1361. fusiformis, 1361. pentacanthus, 1361. Rhopalocanium, 1359. cortinium, 1359. delphicum, 1360. lasanum, 1359. ornatum, 1359. _prismaticum_, 1357. pythia, 1360. Rhopalodictyum, 589. abyssorum, 589. bifidum, 590. curvatum, 591. elongatum, 591. subacutum, 590. truncatum, 589. zittelii, 590.

Sagena, 1605. crucifera, 1606. pertusa, 1606. ternaria, 1606. triangula, 1606. SAGENIDA, 1605. Sagenoscena, 1610. coronata, 1611. cruciata, 1611. ornata, 1610. penicillata, 1611. spathillata, 1611. stellata, 1610. SAGMARIDA, 1612. Sagmarium, 1612. plegmosphærium, 1612. spongodictyum, 1612. trigonizon, 1612. Sagmidium, 1613. crucicorne, 1613. multicorne, 1614. quadricorne, 1614. tricorne, 1613. unicorne, 1613. Sagoplegma, 1614. pyramidophora, 1614. scenophora, 1615. Sagoscena, 1608. castra, 1608. cruciarium, 1609. debilis, 1609. fragilis, 1610. gracilis, 1609. pellorium, 1609. prætorium, 1609. tentorium, 1608. Sagosphæra, 1607. coronilla, 1608. furcilla, 1607. penicilla, 1607. trigonilla, 1607. verticilla, 1607. SAGOSPHÆRIDA, 1601. Saturnalis, 131. annularis, 132. circoideus, 132. circularis, 131. cyclus, 132. rotula, 133. trochoides, 132. Saturnalium, 132. Saturninus, 146. triplex, 146. Saturnulus, 141. annulus, 141. circulus, 141. ellipticus, 141. planetes, 142. _Schizomma_, 645. _quadrilobum_, 645. SEMANTIDA, 953. Semantidium, 960. haeckelii, 961. hexastoma, 960. sexangulum, 960. signatorium, 961. Semantis, 956. biforis, 956. dipyla, 957. distephanus, 957. distoma, 957. sigillum, 957. spinescens, 958. SEMANTISCIDA, 956. Semantiscus, 966. hexapodius, 966, hexapylus, 967. hexaspyris, 966. Semantrum, 958. bütschlii, 959. mülleri, 959. quadrifore, 958. signarium, 960. sphragisma, 959. tetrapylum, 959. tetrastoma, 959. Sepalospyris, 1081. platyphylla, 1081. polyphylla, 1081. Sethamphora, 1249. aerostatica, 1252. ampulla, 1251. costata, 1251. dodecapleura, 1250. enneapleura, 1250. favosa, 1252. hexapleura, 1250. microstoma, 1252. mongolfieri, 1251. serrata, 1251. Sethocapsa, 1310. ampulla, 1311. bulla, 1311. lagena, 1310. macroceros, 1310. nidus, 1311. pyriformis, 1310. staurocephala, 1311. SETHOCAPSIDA, 1309. Sethocephalus, 1298. eucecryphalus, 1298. platycryphalus, 1298. Sethochytris, 1239. barbadensis, 1239. pyramis, 1240. triangula, 1240. triconiscus, 1239. Sethoconus, 1290. ampliatus, 1291. anthocyrtis, 1296. bimarginatus, 1295. cervus, 1292. clathratus, 1295. cucullaris, 1290. facetus, 1296. gracilis, 1295. hexagonalis, 1293. larvatus, 1282. longisetus, 1294. lophophæna, 1292. mitra, 1291. nassa, 1293. orthoceras, 1294. pileus, 1291. profundus, 1294. rayianus, 1291. setosus, 1296. tabulatus, 1293. trichostylus, 1294. trochus, 1290. venosus, 1297. verrucosus, 1293. virgultus, 1296. SETHOCORIDA, 1289. Sethocorys, 1301. achillis, 1301. ajacis, 1302. amphora, 1302. armadillo, 1302. odysseus, 1302. patrocli, 1301. SETHOCYRTIDA, 1288. Sethocyrtis, 1298. agamemnonis, 1300. cancrina, 1292. cassis, 1301. diomedis, 1292. menelai, 1299. oxycephalis, 1299. pleuracantha, 1300. subacuta, 1300. SETHODISCIDA, 422. Sethodiscus, 422. cristatus, 424. echinatus, 424. lenticula, 423. macrococcus, 423. macroporus, 422. micrococcus, 423. microporus, 422. phacoides, 422. radians, 423. Sethomelissa, 1207. hymenoptera, 1238. Sethopera, 1232. lagena, 1233. oceania, 1232. pyrum, 1232. tricostata, 1232. SETHOPERIDA, 1232. Sethophæna, 1285. enneaptera, 1286. hexaptera, 1286. polyptera, 1286. tetraptera, 1285. SETHOPHÆNIDA, 1285. SETHOPHORMIDA, 1143. Sethophormis, 1243. arachnium, 1247. asteriscus, 1244. astrodiscus, 1244. aurelia, 1248. cruciata, 1243. dodecaster, 1248. enneactis, 1247. enneastrum, 1246. eupilium, 1247. floscula, 1249. hexagonalis, 1245. hexalactis, 1245. leptopilium, 1249. leptoscenium, 1249. medusa, 1244. octalactis, 1245. pentalactis, 1244. rotula, 1246. triloba, 1246. umbrella, 1248. SETHOPILIDA, 1195. Sethopilium, 1202. cyrtopus, 1202. macropus, 1203. orthopus, 1202. Sethopyramis, 1253. bicornis, 1256. cyclomma, 1255. dodecalactis, 1256. enneactis, 1254. _eupilium_, 1247. hexagonalis, 1255. hexalactis, 1253. maxima, 1256. quadrata, 1254. quadratella, 1254. scalaris, 1253. spinosa, 1255. trapezoides, 1254. Sethornithium, 1356. dictyopterum, 1356. Sethosphæra, 71. entosiphonia, 71. entosolenia, 71. _rhodococcus_, 237. Sethostaurium, 438. Sethostaurus, 433. conostaurus, 433. coronatus, 434. cruciatus, 434. gigas, 435. orthostaurus, 433. recurvatus, 434. rhombostaurus, 434. Sethostylium, 428. Sethostylus, 429. dentatus, 429. dicylindrus, 428. distyliscus, 428. _endostylus_, 413. hastatus, 429. serratus, 429. spicatus, 430. Siphocampe, 1490. annulosa, 1500. caminosa, 1500. erucosa, 1500. quadrantalis, 1501. spiralis, 1501. tubulosa, 1500. Siphocampium, 1501. Siphocampula, 1499. _Siphonaspis_, 823. _cristata_, 823. Siphonosphæra, 104. chonophora, 107. conifera, 106. cyathina, 105. fragilis, 106. infundibulum, 105. macrosiphonia, 107. marginata, 104. pansiphonia, 104. patinaria, 105. pipetta, 108. polysiphonia, 106. serpula, 107. socialis, 106. tubulosa, 105. Solenosphæra, 112. amalthea, 115. ascensionis, 115. cornucopiæ, 115. megalactis, 114. pandora, 113. serpentina, 114. variabilis, 113. venosa, 114. Soreuma, 713. acervulina, 714. acinosum, 713. irregulare, 713. setosum, 714. spinosum, 714. subglobosum, 713. SOREUMIDA, 712. Sorolarcus, 715. larnacillifer, 715. tetrapylifer, 715. terminalis, 715. SPHÆRELLARIA, 49. SPHÆRIDEA, 50. Sphærocapsa, 798. cruciata, 798. dentata, 798. quadrata, 798. pavimentata, 798. SPHÆROCAPSIDA, 795. SPHÆROIDEA, 50. SPHÆROPHRACTA, 795. Sphærospyris, 1099. globosa, 1100. quadriforis, 1100. sphæra, 1100. SPHÆROSTYLIDA, 133. Sphærostylus, 138. clio, 139. cottus, 140. diadema, 139, flexuosus, 138. hippocampus, 139. liostylus, 138. ophidium, 140. trigla, 140. SPHÆROZOIDA, 38. Sphærozoum, 40. _acuferum_, 46. alveolatum, 43. araucaria, 44. arborescens, 44. armatum, 43. _atlanticum_, 40. _bicellulare_, 25. _bifurcum_, 33. circumtextum, 45. furcatum, 42. furculosum, 42. _fuscum_, 43. geminatum, 45. hamatum, 41. hexactinium, 41. _inerme_, 25. _italicum_, 40. medusinum, 41. _neapolitanum_, 47. octoceras, 44. _orientale_, 1763. ovodimare, 42. _pelagicum_, 28. punctatum, 43. _punctatum_, 42. quadrigeminum, 44. _sanderi_, 1763. _spinulosum_, 40. stellatum, 45. triactinium, 41. trigeminum, 43. variabile, 45. verticillatum, 44. Spiremarium, 692. Spirema, 692. diplospira, 693. flustrella, 692. lentellipsis, 692. melonia, 692. subglobosum, 693. SPIREMIDA, 691. Spiremidium, 693. Spirocampe, 1511. allospira, 1511. callispira, 1511. polyspira, 1511. Spirocyrtidium, 1509. Spirocyrtis, 1508. cornutella, 1509. diplospira, 1510. hemispira, 1510. holospira, 1509. merospira, 1510. scalaris, 1509. Spirocyrtoma, 1509. Spironetta, 701. Spironilla, 702. Spironium, 701. arbustum, 702. diagonale, 702. octonium, 701. spinosum, 702. Spongaster, 596. cruciatus, 597. orthogonus, 598. pentacyclus, 598. quadratus, 597. scyllæus, 598. tetras, 597. Spongasteriscus, 594. armatus, 595. clavatus, 595. furcatus, 595. mucronatus, 595. myelastrum, 596. ovatus, 594. quadricornis, 596. tetraceros, 596. Spongatractus, 350. fusiformis, 351. pachystylus, 350. streptacanthus, 351. Spongechinus, 272. cavus, 273. _multiaculeatus_, 271. serrulatus, 273. setosus, 273. SPONGELLIPSIDA, 341. Spongellipsis, 341. aplysina, 342. aspera, 342. lævis, 342. setosa, 342. spinosa, 342. Spongiomma, 270. asteroides, 272. clavatum, 271. denticulatum, 270. helioides, 271. multiaculeum, 271. radiatum, 270. spathillatum, 270. SPONGIOMMIDA, 270. SPONGOBRACHIDA, 587. Spongobrachium, 587. ellipticum, 588. lanceolatum, 588. Spongocore, 346. chrysalis, 346. cincta, 346. diplocylindrica, 346. puella, 347. pupula, 347. velata, 347. _Spongocyclia_, 577. _charybdoea_, 593. _cycloides_, 578. _elliptica_, 588. _orthogona_, 598. _scyllæa_, 598. _triangularis_, 578. SPONGOCYCLIDA, 573. Spongocyrtis, 1188. arachnoides, 1189. montis ovis, 1189. Spongodictyon, 90. arcadophoron, 91. cavernosum, 91. spongiosum, 90. trigonizon, 91. SPONGODISCIDA, 573. Spongodisculus, 576. Spongodiscus, 576. _aculeatus_, 583. biconcavus, 577. _charybdoeus_, 593. cycloides, 578. _ellipticus_, 588. favus, 577. florealis, 578. mediterraneus, 576. _orthogonus_, 598. _quadricornis_, 596. radiatus, 576. resurgens, 577. _scyllæus_, 598. spiralis, 578. spongocyclia, 578. Spongodruppa, 349. elliptica, 350. frangula, 349. lentisca, 349. pistacia, 349. polyacantha, 350. terebintha, 349. SPONGODRUPPIDA, 348. Spongodrymus, 272. abietinus, 272. elaphococcus, 272. SPONGOLARCIDA, 613. Spongolarcus, 613. amphicentria, 614. dimensivus, 613. lentellipsis, 613. triaxonius, 613. Spongolena, 587. cypselura, 588. rhopalura, 587. spongura, 587. Spongoliva, 352. amygdalina, 352. cerasina, 352. daturina, 353. opuntina, 352. persicina, 352. prunulina, 352. Spongolonche, 579. amphistyla, 580. conostyla, 580. Spongolonchis, 149. compacta, 149. laxa, 149. Spongomelissa, 1209. spongiosa, 1210. SPONGOPHACIDA, 575. Spongophacus, 579. periphæna, 579. Spongophortis, 711. larnacilla, 711. radiosa, 711. spongiosa, 711. Spongopila, 274. dichotoma, 274. verticillata, 275. Spongoplegma, 89. antarcticum, 90. Spongoprunum, 347. amphicylindrus, 348. amphilonche, 347. atractuas, 348. Spongopyramis, 1260. spongiosa, 1261. spongoplecta, 1261. Spongosphæra, 282. helioides, 283. _pachystyla_, 350. polyacantha, 282. quadricuspis, 283. _rhabdostyla_, 584. streptacantha, 282. SPONGOSPHÆRIDA, 52. Spongospira, 578. _florealis_, 578. _spiralis_, 578. Spongostaurus, 582. cruciatus, 582. hastatus, 582. quadratus, 582. serratus, 582. SPONGOSTYLIDA, 148. Spongostylidium, 150. streptacanthum, 150. Spongostylus, 149. gladiatus, 150. hastatus, 149. _prunococcus_, 354. serratus, 150. Spongothamnus, 274. furcatus, 274. scoparius, 274. Spongotripus, 580. irregularis, 581. neumayri, 581. regularis, 580. strepsiceros, 581. ypsilon, 581. SPONGOTROCHIDA, 579. Spongotrochiscus, 585. Spongotrochus, 585. _arachnius_, 583. brevispinus, 586. _craticulatus_, 583. ehrenbergii, 1763. _heteracanthus_, 584. longispinus, 586. multispinus, 586. parma, 587. scutella, 586. SPONGURIDA, 339. Spongurus, 343. asper, 344. cylindricus, 344. phalanga, 343. radians, 345. _salpa_, 614. spongechinus, 345. stuparius, 343. stypticus, 343. tricolus, 344. Spongoxiphus, 353. prunococcus, 354. sphærococcus, 353. SPUMELLARIA, 6. Spyrida, 1015. SPYRIDINA, 1015. _Spyridobotrys_, 1083. _trinacria_, 1083. SPYROIDEA, 1015. Stauracantha, 761. bifurca, 764. diplostaura, 762. johannis, 763. murrayana, 763. orthostaura, 762. pinnulata, 763. quadrifurca, 764. scalaris, 763. stauraspis, 764. tetrastaura, 762. STAURACANTHIDA, 758. Stauracanthidium, 764. Stauracanthonium, 762. STAURACONTIDA, 163. Stauracontium, 163. antarcticum, 165. cruciferum, 164. daturæforme, 164. papillosum, 165. setosum, 165. sparganium, 165. tetracanthum, 164. tetracontium, 164. Stauractinium, 478. Stauractura, 477. medusina, 478. quadrata, 478. tetragona, 478. Stauracturium, 477. Stauralastrum, 540. antiquum, 541. clavigerum, 541. cruciforme, 540. dilatatum, 541. horridum, 542. lanceolatum, 540. ordo, 540. rhopalophorum, 541. staurolonche, 542. Staurancistra, 162. quadricuspis, 162. Staurasparium, 831. STAURASPIDA, 830. Stauraspidium, 831. Stauraspis, 831. cruciata, 831. furcata, 832. stauracantha, 832. xiphacantha, 831. Staurectodiscus, 416. Staurentodiscus, 416. STAUROCARYIDA, 167. Staurocaryum, 167. arborescens, 167. STAUROCROMYIDA, 166. Staurocromyum, 166. quadrispinum, 166. quadruplex, 166. Staurocyclia, 465. cruciata, 465. magniducis, 466. phacostaurus, 465. serrata, 465. Staurodictya, 506. ciliata, 506. cruciata, 507. elegans, 507. grandis, 508. medusa, 506. ocellata, 508. quadrispina, 507. splendens, 508. Staurodoras, 168. liassica, 168. mojsisovicsi, 168. spongosphæra, 168. wandæ, 169. STAURODORIDA, 168. Staurolithium, 771. _cruciatum_, 771. Staurolonche, 159. aperta, 159. brunonis, 159. epicurii, 161. feuerbachii, 160. gassendii, 161. hexagona, 158. holbachii, 160. lucretii, 161. moleschottii, 160. pertusa, 159. spinozæ, 159. straussii, 160. STAUROLONCHIDA, 158. Staurolonchidium, 162. artioscelides, 162. perspicuum, 162. Stauropelta, 859. cruciata, 859. stauropora, 859. Staurosphæra, 153. andreæ, 154. apostolorum, 155. bartholomæi, 156. christiana, 153. crassa, 155. cruciata, 153. jacobi, 154. johannis, 153. judæ, 155. matthæi, 156. pauli, 153. petri, 153. phillippi, 154. simonis, 154. thaddæi, 156. thomæ, 155. STAUROSPHÆRIDA, 151. Staurospira, 507. STAUROSTYLIDA, 152. Staurostylus, 156. germanicus, 157. græcus, 156. latinus, 157. STAUROTHOLIDA, 670. Staurotholonium, 675. alternatum, 675. bicruciatum, 675. biquadratum, 675. lenticulare, 676. octodoratium, 676. octodoronium, 676. Staurotholus, 673. cruciatus, 673. decastylus, 674. dodecastylus, 674. octostylus, 674. polystylus, 674. quadratus, 673. tetrastylus, 673. Stauroxiphos, 163. gladius, 163. Stegaspis, 819. Stephanastrum, 549. capitatum, 549. quadratum, 549. rhombus, 549. STEPHANIDA, 937. Stephaniscus, 965. medusinus, 965. quadrifurcus, 965. quadrigatus, 965. tetrapodius, 965. Stephanium, 952. quadrupes, 952. tetrapus, 952. Stephanolithia, 953. _mülleri_, 959. _spinescens_, 958. Stephanophæna, 1178. Stephanospyris, 1042. cordata, 1042. excellens, 1043. verticillata, 1043. STEPHIDA, 931. STEPHOIDEA, 931. Stichocampe, 1443. convergens, 1444. divergens, 1444. Stichocapsa, 1515. compacta, 1517. compressa, 1516. cylindrica, 1518. hexacola, 1517. monstrosa, 1517. paniscus, 1518. pentacola, 1517. pyriformis, 1516. quadrigata, 1515. radicula, 1518. subglobosa, 1516. subligata, 1518. tetracola, 1515. tricincta, 1516. STICHOCAPSIDA, 1511. STICHOCORIDA, 1468. Stichocorys, 1479. bærii, 1479. huschkei, 1480. mülleri, 1480. okenii, 1480. panderi, 1479. rathkei, 1480. wolffii, 1479. STICHOCYRTIDA, 1434. Stichocyrtis, 1489. Sticholagena, 1449. Stichopera, 1447. clavata, 1449. lagena, 1448. ovata, 1448. pectinata, 1449. serrata, 1448. verticillata, 1449. STICHOPERIDA, 1447. Stichoperina, 1448. Stichophæna, 1465. darwiniana, 1465. goetheana, 1466. nonaria, 1466. novena, 1466. ritteriana, 1465. STICHOPHÆNIDA, 1463. Stichophænidium, 1465. Stichophænoma, 1466. STICHOPHORMIDA, 1454. Stichophormis, 1454. cornutella, 1455. lucerna, 1455. novena, 1455. pyramidalis, 1454. radiata, 1456. Stichophormiscus, 1455. Stichophormium, 1454. STICHOPILIDA, 1436. Stichopilidium, 1438. Stichopilium, 1436. bicorne, 1437. campanulatum, 1438. cortina, 1437. costatum, 1437. davisianum, 1437. macropterum, 1438. pectinatum, 1439. thoracopterum, 1439. triserratum, 1438. Stichopodium, 1447. dictyopodium, 1447. Stichopterium, 1444. dictyopodium, 1445. pterocanium, 1445. virgineum, 1445. _Stichopterygium_, 1442. _tanypterum_, 1442. _anomalum_, 1442. Stigmosphæra, 68. actinocentra, 68. Stomatodiscus, 502. amphistomus, 502. osculatus, 503. Streblacantha, 706. calcarina, 706. hastigerina, 707. siderolina, 706. STREBLACANTHIDA, 704. Streblonia, 704. bulimina, 705. globigerina, 704. planorbulina, 705. polymorphina, 705. pulvinulina, 706. rosalina, 705. _siderolina_, 706. uvigerina, 704. STREBLONIDA, 702. Streblopyle, 707. helicina, 707. spirulina, 707. STREBLOPYLIDA, 704. Stylactis, 532. _triangulum_, 533. _zittelii_, 534. Stylartus, 357. bipolaris, 357. bicuspis, 357. palatus, 358. penicillus, 358. Stylatractus, 328. carduus, 330. compactus, 329. disetanius, 331. fusiformis, 329. giganteus, 329. neptunus, 328. papillosus, 331. sethoporus, 330. variabilis, 330. Stylectodiscus, 413. Stylentodiscus, 413. Stylochlamydium, 514. æquale, 515. asteriscus, 514. limbatum, 514. perispirale, 515. spongiosum, 516. venustum, 515. Stylocoronis, 982. Stylocromyum, 147. amphiconus, 147. amphipyramis, 147. _tetraphractum_, 335. Stylocyclia, 462. amphacantha, 463. _arachnia_, 510. dimidiata, 462. excavata, 463. prionacantha, 462. STYLOCYCLIDA, 461. Stylodictya, 509. arachnia, 510. _bispiralis_, 497. centrospira, 512. clavata, 513. dujardinii, 513. echinastrum, 513. _forbesii_, 510. gracilis, 509. haeckelii, 510. hastata, 510. heliospira, 512. hertwigii, 513. multispina, 510. _ocellata_, 508. octogonia, 511. perispira, 511. _quadrispina_, 507. setigera, 512. solmaris, 511. _splendens_, 508. stellata, 510. STYLODICTYIDA, 503. Stylodiscus, 413. amphistylus, 413. endostylus, 413. Stylosphæra, 133. calliope, 134. _carduus_, 330. clio, 134. _coronata_, 326. dixyphos, 135. erato, 137. euterpe, 135. _flexuosa_, 138. _hippocampus_, 324. hispida, 136. _holosphæra_, 150. jugata, 137. _lævis_, 327. liostylus, 136. _megadictya_, 301. melpomene, 135. musa, 133. nana, 136. _ophidium_, 140. polyhymnia, 134. _radiosa_, 334. setosa, 135. _spinulosa_, 332. _sulcata_, 333. terpsichore, 137. _testudo_, 325. thalia, 137. urania, 134. STYLOSPHÆRIDA, 121. Stylospira, 512. _arachnia_, 513. _dujardinii_, 513. _heliospira_, 512. Stylospongia, 584. _huxleyi_, 585. Stylospongidium, 586. _geddesii_, 585. Stylostaurus, 157. caudatus, 157. gladiatus, 158. Stylotrochiscus, 583. Stylotrochus, 583. arachnius, 583. craticulatus, 583. geddesii, 585. helianthus, 584. heteracanthus, 584. huxleyi, 585. rhabdostylus, 584. Stypolarcus, 614. spongiosus, 614. Styposphæra, 86. spongiacea, 87. spumacea, 87. stupacea, 87.

Taurospyris, 1058. bovina, 1058. cervina, 1058. Tessarasparium, 835. TESSARASPIDA, 830. Tessaraspidium, 838. _quadratum_, 838. Tessaraspis, 835. arachnoides, 836. circularis, 837. concreta, 838. diodon, 837. _elegans_, 844. _icosastaura_, 846. hexagonalis, 836. irregularis, 838. micropora, 827. pentagonalis, 836. quadrata, 838. quadriforis, 837. rotunda, 838. tetragonalis, 836. trigonalis, 836. Tessarastrum, 547. brunonis, 548. democriti, 548. spinozæ, 546. straussii, 547. Tessarospyris, 1045. clathrobursa, 1045. nuciformis, 1046. seminulum, 1046. _Tetracorethra_, 1044. _mirabilis_, 1044. Tetracoronis, 981. Tetracranastrum, 552. Tetracubus, 994. TETRACYRTIDA, 1434. Tetrahedrina, 1238. pyramidalis, 1238. pyriformis, 1238. quadricornis, 1239. Tetralacorys, 1370. Tetraphormis, 1243. Tetraplagia, 911. abietina, 912. geometrica, 911. phænaxonia, 911. TETRAPLAGIDA, 941. Tetraplecta, 923. pinigera, 924. quadricornis, 924. tetrahedra, 923. TETRAPLECTIDA, 923. Tetrapyle, 645. cardiopyle, 646. circopyle, 645. circularis, 645. cladacantha, 648. cruciata, 647. dodecaceros, 649. fusiformis, 646. nephropyle, 645. octacantha, 648. pleuracantha, 646. pluteus, 649. _polyacantha_, 1761. quadricornis, 647. quadrigata, 648. quadriloba, 645. staurophora, 647. tetracantha, 647. transversa, 646. turrita, 649. Tetrapylonium, 657. armatum, 659. octacanthum, 658. pantellipticum, 658. quadrangulare, 658. reniforme, 658. Tetrarrhabda, 1044. Tetrasolenia, 113. _quadrata_, 113. _venosa_, 114. TETRASPHÆRIDA, 52. TETRASPYRIDA, 1043. Tetraspyris, 1043. calcarata, 1045. cubica, 1044. scoparia, 1045. stephanium, 1044. tetracorethra, 1044. Tetroniscus, 487. _Thamnospyris_, 1070. _thamnopodia_, 1071. Thalassicolla, 18. _acufera_, 46. australis, 20. _cavispicula_, 1551. maculata, 21. melacapsa, 21. nucleata, 20. _papillosa_, 22. _pelagica_, 23. pellucida, 19. _punctata_, 25. _sanguinolenta_, 22. spumida, 19. zanclea, 19. Thalassicollarium, 18. THALASSICOLLIDA, 10. Thalassicollidium, 20. Thalassolampe, 16. margarodes, 16. maxima, 17. _primordialis_, 13. Thalassophysa, 21. papillosa, 22. pelagica, 23. sanguinolenta, 22. Thalassopila, 17. cladococcus, 17. Thalassoplancta, 36. brevispicula, 36. _cavispicula_, 1551. longispicula, 36. Thalassosphæra, 31. belonium, 31. _bifurca_, 33. rhaphidium, 31. THALASSOSPHÆRIDA, 29. Thalassoxanthium, 32. bifurcum, 33. cervicorne, 33. furcatum, 33. hexactinium, 32. medusinum, 32. octoceras, 34. ovodimare, 34. punctatum, 34. triactinium, 32. triradiatum, 32. Thecosphæra, 78. æquorea, 80. capillacea, 81. diplococcus, 81. dodecactis, 82. entactinia, 81. favosa, 79. floribunda, 79. icosactis, 82. inermis, 80. maxima, 82. medusa, 80. micropora, 81. phænaxonia, 79. triplodictyon, 79. THECOSPHÆRIDA, 78. Theocalyptra, 1397. cornuta, 1398. discoides, 1398. orci, 1397. veneris, 1397. Theocampana, 1422. Theocampe, 1422. cassis, 1424. collaris, 1425. costata, 1426. cryptocephala, 1426. cryptoprora, 1423. ehrenbergii, 1422. gemmata, 1425. megalopora, 1425. nucula, 1423. ovulum, 1424. pirum, 1423. sphærothorax, 1424. stenostoma, 1423. versipellis, 1425. Theocentra, 1424. Theocapsa, 1426. aldrovandi, 1428. aristotelis, 1427. bærii, 1430. cuvieri, 1430. darwinii, 1431. democriti, 1427. forskalii, 1429. galeni, 1427. gessneri, 1428. lamarckii, 1430. linnæi, 1429. malpighii, 1428. mülleri, 1431. pallasii, 1429. plinii, 1427. rathkei, 1430. sarsii, 1431. schwannii, 1431. wolffii, 1429. wottonis, 1428. Theocapsetta, 1426. THEOCAPSIDA, 1426. Theocapsilla, 1427. Theocapsomma, 1428. Theocapsura, 1430. Theoconus, 1399. ægeus, 1400. amplus, 1402. ampullaceus, 1402. ariadnes, 1402. campanulatus, 1400. dionysius, 1402. ficus, 1403. jovis, 1401. junonis, 1401. laterna, 1403. longicornis, 1401. orthoconus, 1400. zancleus, 1399. zanguebaricus, 1400. Theocorax, 1399. Theocorbis, 1401. THEOCORIDA, 1396. Theocoronium, 1415. Theocorusca, 1407. Theocorys, 1414. alauda, 1418. ampullacea, 1402. apollinis, 1418. attenuata, 1417. bachabunda, 1417. cretica, 1415. dianæ, 1416. _ficus_, 1403. hyalothorax, 1417. _longicornis_, 1370. martis, 1419. mercurii, 1419. minervæ, 1419. obliqua, 1417. ovata, 1416. plutonis, 1416. scolopax, 1416. sphærophila, 1418. tuberculata, 1419. turgidula, 1415. veneris, 1415. Theocorypha, 1405. Theocorythium, 1416. THEOCYRTIDA, 1395. Theocyrtis, 1405. aspera, 1408. barbadensis, 1406. cylindrica, 1406. elegans, 1406. macroceros, 1407. microtheca, 1407. oenophila, 1408. paupera, 1407. proserpinæ, 1408. ptychodes, 1408. trachelius, 1405. Theodiscoma, 414. Theodiscura, 415. Theodiscus, 413. christianus, 414. divinus, 414. nirwana, 415. trinitatis, 414. vanitatis, 415. Theopera, 1357. chytropus, 1358. cortina, 1358. fusiformis, 1357. luscinia, 1358. prismatica, 1357. pyramis, 1357. THEOPERIDA, 1354. Theophæna, 1394. corona, 1394. nonaria, 1395. THEOPHÆNIDA, 1393. THEOPHORMIDA, 1366. Theophormis, 1366. callipilium, 1367. cruciata, 1367. medusa, 1367. senaria, 1368. THEOPILIDA, 1315. Theosyringium, 1409. pipetta, 1409. siphonium, 1409. tibia, 1409. tubulus, 1411. Theopilium, 1321. cranoides, 1322. tricostatum, 1322. triradiatum, 1322. Theopodium, 1328. pyramidale, 1328. tricostatum, 1328. THEROSPYRIDA, 1055. Therospyris, 1058. canis, 1058. felis, 1059. leo, 1059. Tholartus, 663. isocolus, 664. paniscus, 664. sagitta, 665. tricolus, 664. tripanis, 665. Tholocubus, 677. tessellatus, 677. tesseralis, 678. tesserarius, 677. Tholodes, 665. cupula, 665. Tholoma, 671. metallasson, 672. quadrigeminum, 672. THOLONIDA, 660. Tholonium, 678. bicubicum, 678. ellipticum, 679. hexonium, 679. sphæricum, 679. sphæronium, 679. Tholospira, 699. cervicornis, 700. dendrophora, 700. hystrix, 700. nautiloides, 699. spinosa, 696. Tholospirema, 699. Tholospironium, 700. THOLOSPYRIDA, 1077. Tholospyridium, 1079. Tholospyris, 1078. cupola, 1080. fenestrata, 1079. galeata, 1079. ramosa, 1079. tripodiscus, 1079. Tholospyrium, 1078. Tholostaurus, 670. cruciformis, 670. dodecabeles, 671. octobelonis, 671. polybelonis, 671. quadrigatus, 670. tetrabelonis, 671. _Tholothauma_, 682. _ellipsoides_, 682. Thoracaspis, 862. bipennis, 862. circopora, 862. ellipsoides, 862. nephropora, 862. Thyrsocyrtis, 1350. _anthophora_, 1491. arborescens, 1350. _bachabunda_, 1417. _bromia_, 1349. _dionysia_, 1402. furcata, 1351. _jacchia_, 1402. _lyæa_, 1348. _oenophila_, 1408. _radicata_, 1351. _reticulata_, 1274. rhizodon, 1350. rhizopodium, 1351. rhizopus, 1351. trifida, 1352. TIAROSPYRIDA, 1078. Tiarospyris, 1082. amphora, 1083. galea, 1082. mitra, 1082. pervia, 1082. Toxarium, 995. bifurcum, 997. circospyris, 995. constrictum, 996. cordatum, 996. costatum, 997. furcatum, 997. pedatum, 997. subcirculare, 996. thorax, 996. Toxellium, 995. Toxidium, 996. Toxonium, 997. TREMATODISCIDA, 491. Trematodiscus, 492. _concentricus_, 492. _ellipticus_, 494. _flustrella_, 493. _haeckelii_, 1763. _helicoides_, 496. _heterocyclus_, 494. _macroporus_, 493. _microporus_, 493. _orbiculatus_, 492. _sorites_, 493. _soritoides_, 1762. Triacartus, 1436. _Triactinosphæra_, 590. _zittelii_, 590. Triactiscus, 432. tricuspis, 432. tripodiscus, 432. tripyramis, 432. Tribonosphæra, 98. centripetalis, 98. Triceraspyris, 1029. arborescens, 1032. corallorrhiza, 1031. cortiniscus, 1030. damæcornis, 1032. didiceros, 1030. furcata, 1031. gazella, 1031. giraffa, 1031. longicornis, 1032. maniculata, 1031. tripodiscus, 1030. _Trichogromia_, 1661. _hirsuta_, 1661. Tricircarium, 985. Tricirconium, 986. Tricolocampe, 1411. amphizona, 1413. arcta, 1414. cingulata, 1414. cylindrica, 1412. doliolum, 1414. panthera, 1413. polyzona, 1412. pupa, 1412. stenozona, 1413. urnula, 1413. Tricolocampium, 1412. Tricolocamptra, 1413. Tricolocapsa, 1431. brownii, 1433. decandollei, 1433. dioscoridis, 1432. linnæi, 1432. schleidenii, 1433. theophrasti, 1432. Tricolocapsium, 1433. Tricolocapsula, 1432. Tricolospyris, 1097. baconiana, 1098. kantiana, 1098. leibnitziana, 1098. newtoniana, 1098. _Tricranastrum_, 541. _wyvillei_, 551. Trictenartus, 1440. Tricyclarium, 987. Tricyclidium, 984. dictyospyris, 984. semantrum, 985. Tricyclonium, 987. TRICYRTIDA, 1313. Tridictyopus, 1145. conulus, 1145. elegans, 1145. vatillum, 1145. Trigonactinium, 472. Trigonactura, 471. lanceolata, 472. pythagoræ, 471. rhopalastrella, 471. triacantha, 472. trigonobrachia, 472. trigonodiscus, 472. trixiphos, 473. Trigonacturium, 471. Trigonastrum, 539. gegenbauri, 539. krohnii, 539. regulare, 539. Trigonocyclia, 464. triangularis, 464. Triodiscus, 566. lenticula, 566. trigonus, 567. spinosus, 567. Triolena, 564. hexabelone, 564. primordialis, 564. tribelone, 564. trigonalis, 564. trispinosa, 564. Trioniscus, 486. Triopyle, 564. circulus, 565. cordigera, 565. hexagona, 565. renigera, 565. spinigera, 566. trigona, 565. TRIOPYLIDA, 563. TRIOSPHÆRIDA, 52. Triospyridium, 1032. Triospyris, 1030. Triospyrium, 1030. TRIOSTEPHIDA, 967. Triostephus, 983. Tripilidium, 1140. cladopodium, 1142. clavatum, 1141. cortina, 1140, costatum, 1141. dichopodium, 1142. elongatum, 1142. hemisphæricum, 1140. lychnocanium, 1141. ovatum, 1141. Triplagia, 908. horizontalis, 909. primordialis, 909. triradialis, 909. TRIPLAGIDA, 908. Triplecta, 921. triactis, 922. triangulum, 921. TRIPLECTIDA, 921. TRIPLOZONARIA, 656. TRIPOCALPIDA, 1133. Tripocalpis, 1135. cortinaris, 1137. galea, 1136. plectaniscus, 1136. tricostata, 1136. triserrata, 1136. Tripocoronis, 981. Tripocubus, 994. TRIPOCYRTIDA, 1192. Tripocyrtis, 1201. _challengeri_, 1231. plagoniscus, 1201. plectaniscus, 1202. tripodiscus, 1202. Tripodictya, 505. triacantha, 505. tribelonia, 505. trigonaria, 505. Tripodiscinus, 1143. Tripodisculus, 1144. Tripodocorys, 1142. Tripodonium, 1137. campanulatum, 1137. ovatum, 1137. Tripodiscium, 1143. campanula, 1144. clavatum, 1143. furcatum, 1144. ovatum, 1143. ramosum, 1144. sphærocephalum, 1144. tristylospyris, 1143. Tripospyrantha, 1025. Tripospyrella, 1026. TRIPOSPYRIDA, 1025. Tripospyris, 1025. capitata, 1025. clavata, 1028. conifera, 1027. cortina, 1025. cortiniscus, 1026. diomma, 1026. eucolpos, 1029. _euscenium_, 1147. furcata, 1021. hexomma, 1028. semantidium, 1029. semantis, 1026. semantrum, 1027. tessaromma, 1028. tribrachiata, 1029. triomma, 1026. triplecta, 1027. Tripospyrissa, 1027. Tripospyromma, 1028. Tripterocalpis, 1137. conoptera, 1138. ogmoptera, 1138. phylloptera, 1138. TRIPYLEA, 1521. _Trisolenia_, 113. _megalactis_, 114. _zanguebarica_, 97. Trissocircus, 985. binellipsis, 985. globus, 986. lentellipsis, 985. octahedrus, 986. octostoma, 986. TRISSOCYCLIDA, 982. Trissocyclus, 986. sphæridium, 987. stauroporus, 987. triaxonius, 987. Trissopilium, 1138. lithomelissa, 1139. tetraplecta, 1139. Tristephaniscus, 984, Tristephanium, 982. dimensivum, 983. hertwigii, 983. octopyle, 983. quadricorne, 984. Tristylocorys, 1140. Tristylospyris, 1032. clavipes, 1033. furcata, 1034. palmipes, 1033. ramosa, 1034. scaphipes, 1033. triceros, 1033. tripodiscium, 1034. Tristylospyrula, 1033. Tristylospyrium, 1034. Trizonium, 637. amphibelonium, 638. constrictum, 637. decabelonium, 639. dodecabelos, 640. hexabelonium, 639. hexagonium, 638. octobelonium, 639. octogonium, 638. pleurobelonium, 638. staurobelonium, 639. tricinctum, 637. TROCHODISCIDA, 412. Trochodisculus, 417. Trochodiscus, 417. cenophacus, 417. cingillum, 419. echiniscus, 418. medusinus, 417. odontotrochus, 418. solaris, 418. stellaris, 418. Trypanosphæra, 109. coronata, 110. dentata, 110. terebrata, 110. transformata, 111. trepanata, 110. TYMPANIDA, 987. Tympanidium, 1003. barbadense, 1004. binoctonum, 1004. foliosum, 1003. spinosum, 1003. staurocircum, 1004. Tympaniscus, 1001. bipes, 1001. corona, 1001. dipodiscus, 1001. _dizonius_, 973. dodecaster, 1002. fibula, 1002. quadrupes, 1002. tripodiscus, 1002. Tympanura, 1003. Tympanomma, 1004. Tuscarantha, 1706. Tuscaretta, 1707. Tuscaridium, 1709. cygneum, 1709. lithornithium, 1710. Tuscarilla, 1708. Tuscarora, 1706. belknapii, 1708. bisternaria, 1706. _cygnea_, 1709. murrayi, 1706. porcellana, 1708. tetrahedra, 1707. tubulosa, 1707. wyvillei, 1707. TUSCARORIDA, 1702. Tuscarusa, 1707. medusa, 1709.

Urocyrtis, 1762. amaliæ, 1762. emmæ, 1762. stephanii, 1762.

Xanthiosphæra, 119. capillacea, 119. erinacea, 120. lappacea, 120. Xiphacantha, 758. alata, 761. ancorata, 760. ciliata, 761 _cruciata_, 754. crucifera, 759. emarginata, 759. falcata, 759. _foliosa_, 754. macroptera, 760. _murrayana_, 763. _pectinata_, 757. platyptera, 761. quadridentata, 758. _serrata_, 757. spinulosa, 759. stauroptera, 760. trigonoptera, 760. Xiphacanthidium, 760. Xiphacanthonium, 758. Xiphatractus, 332. armadillo, 332. chlamydophorus, 333. dasypus, 333. euphractus, 332. glyptodon, 334. radiosus, 334. spinulosus, 332. sulcatus, 333. Xiphodictya, 503. amphibelonia, 503. amphirrhopalia, 504. staurospira, 504. heliospira, 504. Xiphoptera, 777. dodecactena, 778. icosactena, 778. tessaractena, 778. Xiphosphæra, 123. astræa, 126. _bipolaris_, 297. ceres, 126. clavigera, 126. euphrosyne, 124. flora, 125. gæa, 123. gigantea, 125. hebe, 127. luna, 123. juno, 125. maxima, 124. pallas, 124. planeta, 123. venus, 123. vesta, 126. Xiphospira, 504. XIPHOSTYLIDA, 122. Xiphostylus, 127. alauda, 128. alca, 130. alcedo, 127. anhinga, 128. ardea, 131. cuculus, 129. edolius, 130. emberiza, 131. falco, 130. gallus, 128. motacilla, 127. phasianus, 127. picus, 129. trochilus, 129. trogon, 129.

ZONARIDA, 682. Zonarium, 684. octangulum, 685. quadrigatum, 685. quadrispinum, 685. tetratholium, 685. Zonaspis, 833. æquatorialis, 834. cingulata, 834. fragilis, 833. Zonidium, 687. octostylium, 688. octotholium, 688. Zoniscus, 686. hexathalamius, 686. hexatholius, 687. octacanthus, 667. rectangulus, 686. tetracanthus, 687. ZONODISCIDA, 411. Zonodiscus, 412. saturnalis, 412. Zygacantha, 746. complanata, 748. compressa, 747. costata, 746. dichotoma, 747. dicopa, 748. foliacea, 748. furcata, 747. lanceolata, 746. semicompressa, 748. Zygacantharium, 746. ZYGACANTHIDA, 742. Zygacanthidium, 747. Zygacanthonium, 748. ZYGARTIDA, 397. Zygartus, 401. chrysalis, 401. doliolum, 401. _larvalis_, 398. _virginis_, 369. Zygocampe, 399. chrysalidium, 400. corasium, 400. pupula, 399. ZYGOCAMPIDA, 392. Zygocircus, 945. acacia, 947. bütschlii, 948. dodecanthus, 947. hexagonus, 947. pentagonus, 946. polygonus, 947. productus, 958. rhombicus, 946. sagittalis, 946. tetragonus, 946. trigonus, 946. triquetrus, 347. ZYGOCYRTIDA, 1015. ZYGOSPYRIDA, 1021. Zygospyris, 1055. equus, 1056. quadrupes, 1055. Zygostaurus, 774. amphithectus, 774. arcuatus, 774. caudatus, 775. cornutus, 775. frontalis, 775. longicornis, 774. sagittalis, 775. ZYGOSTEPHANIDA, 970. Zygostephaniscus, 972. Zygostephanium, 972. constrictum, 973. dizonium, 973. paradictyum, 973. Zygostephanus, 970. bicornis, 972. dissocircus, 971. mülleri, 971. ramosus, 971. reniformis, 972 serratus, 971. violina, 972.

Notes.

[1] _Cystidium_ = Small vesicle; [Greek: kystidion].

[2] _Nassella_ = Small wicker cage for fishing.

[3] _Triplagia_ = Triangular or three-radial; [Greek: triplagios].

[4] _Plagiacantha_ = Having spines on the sides; [Greek: plagios], [Greek: akantha].

[5] _Tetraplagia_ = Four-sided; [Greek: tetraplagios].

[6] _Plagoniscus_ = Side-windlass; [Greek: plagos], [Greek: oniskos].

[7] _Plagonidium_ = Small side-article; [Greek: plagônidion].

[8] _Plagiocarpa_ = Having its fruit (the central capsule) on the side; [Greek: plagiokarpos].

[9] _Hexaplagia_ = Six-sided; [Greek: hexaplagios].

[10] _Plagonium_ = Side-article; [Greek: plagos], [Greek: ônion].

[11] _Polyplagia_ = Manifold; [Greek: polyplagios].

[12] _Triplecta_ = Hunting net with three beams; [Greek: tris], [Greek: plektê].

[13] _Plectophora_ = Bearing a hunting net; [Greek: plektê], [Greek: phoros].

[14] _Tetraplecta_ = Hunting net with four beams; [Greek: tetra], [Greek: plektê].

[15] _Plectaniscus_ = Shell of wickerwork; [Greek: plektaniskos].

[16] _Periplecta_ = Surrounded by a hunting net; [Greek: peri], [Greek: plektê].

[17] _Hexaplecta_ = Hunting net with six beams; [Greek: hexa], [Greek: plektê].

[18] _Plectanium_ = Small wickerwork or network; [Greek: plektanê].

[19] _Polyplecta_ = Much entwined; [Greek: polyplektos].

[20] _Archicircus_ = Primordial ring; [Greek: archi], [Greek: kirkos].

[21] _Lithocircus_ = Ring of silex; [Greek: lithos], [Greek: kirkos].

[22] _Zygocircus_ = Yoked or symmetrical ring; [Greek: zygon], [Greek: kirkos].

[23] _Dendrocircus_ = Ring bearing trees; [Greek: dendron], [Greek: kirkos].

[24] _Cortina_ = Tripod.

[25] _Stephanium_ = Small crown or garland; [Greek: stephanion].

[26] _Semantis_ = Signet-ring; [Greek: sêmantis].

[27] _Semantrum_ = Signet-ring; [Greek: sêmantron].

[28] _Semantidium_ = Small signet-ring; [Greek: sêmantidion].

[29] _Clathrocircus_ = Lattice-ring; [Greek: klêthron], [Greek: kirkos].

[30] _Cortiniscus_ = Small cortina or tripod.

[31] _Stephaniscus_ = Small coronet or garland; [Greek: stephaniskos].

[32] _Semantiscus_ = Small signet-ring; [Greek: sêmantiskos].

[33] _Zygostephanus_ = Yoked ring; [Greek: zygon], [Greek: stephanos].

[34] _Zygostephanium_ = Small yoked ring; [Greek: zygon], [Greek: stephanion].

[35] _Coronidium_ = Small crown; [Greek: korônidion].

[36] _Acanthodesmia_ = Thorn-band; [Greek: akantha], [Greek: desmion].

[37] _Eucoronis_ = Good crown; [Greek: eu], [Greek: korônis].

[38] _Plectocoronis_ = Crown with framework; [Greek: plektos], [Greek: korônis].

[39] _Podocoronis_ = Crown with feet; [Greek: pous], [Greek: korônis].

[40] _Tristephanium_ = Small crown with three rings; [Greek: tris], [Greek: stephanion].

[41] _Tricyclidium_ = Composed of three small crossed circles; [Greek: tris], [Greek: kyklidion].

[42] _Trissocircus_ = Composed of three crossed circles; [Greek: trissos], [Greek: kirkos].

[43] _Trissocyclus_ = Composed of three crossed rings; [Greek: trissos], [Greek: kyklos].

[44] _Protympanium_ = Primordial drum; [Greek: protympanion].

[45] _Acrocubus_ = Perfect cube; [Greek: akros], [Greek: kybos].

[46] _Toxarium_ = Small bow; [Greek: toxarion].

[47] _Microcubus_ = Small cube; [Greek: mikros], [Greek: kybos].

[48] _Octotympanum_ = Drum with eight gates; [Greek: oktô], [Greek: tympanon].

[49] _Tympaniscus_ = Little drum; [Greek: tympaniskos].

[50] _Tympanidium_ = Small drum; [Greek: tympanidion].

[51] _Paratympanum_ = Side-drum; [Greek: para], [Greek: tympanon].

[52] _Lithotympanum_ = Drum of silex; [Greek: lithos], [Greek: tympanon].

[53] _Dystympanium_ = Hideous drum; [Greek: dys], [Greek: tympanion].

[54] _Prismatium_ = A small prism; [Greek: prismation].

[55] _Pseudocubus_ = False cube; [Greek: pseudos], [Greek: kybos].

[56] _Lithocubus_ = Cube of silex; [Greek: lithos], [Greek: kybos].

[57] _Circotympanum_ = Drum with rings; [Greek: kirkos], [Greek: tympanon].

[58] _Eutympanium_ = Nice small drum; [Greek: eu], [Greek: tympanion].

[59] _Tripospyris_ = Basket with a tripod; [Greek: tripos], [Greek: spyris].

[60] _Triceraspyris_ = Basket with three horns; [Greek: trikeras], [Greek: spyris]

[61] _Tristylospyris_ = Basket with three styles; [Greek: tristylos], [Greek: spyris].

[62] _Cephalospyris_ = Head-like basket; [Greek: kephalê], [Greek: spyris].

[63] _Dipospyris_ = Basket with two feet; [Greek: dipous], [Greek: spyris].

[64] _Brachiospyris_ = Basket with two arms; [Greek: brachiôn], [Greek: spyris].

[65] _Dendrospyris_ = Basket with arborescent feet; [Greek: dendron], [Greek: spyris].

[66] _Dorcadospyris_ = Basket with two horns, similar to an antelope; [Greek: dorkas], [Greek: spyris].

[67] _Gamospyris_ = Basket with two feet grown together; [Greek: gamos], [Greek: spyris].

[68] _Stephanospyris_ = Basket with a garland; [Greek: stephanos], [Greek: spyris].

[69] _Tetraspyris_ = Basket with four feet; [Greek: tetra], [Greek: spyris].

[70] _Tessarospyris_ = Basket with four feet; [Greek: tessara], [Greek: spyris].

[71] _Hexaspyris_ = Basket with six feet; [Greek: hexa], [Greek: spyris].

[72] _Liriospyris_ = Lily-basket; [Greek: leirion], [Greek: spyris].

[73] _Cantharospyris_ = Basket with six feet, like a beetle; [Greek: kantharos], [Greek: spyris].

[74] _Clathrospyris_ = Latticed basket; [Greek: klêthron], [Greek: spyris].

[75] _Aegospyris_ = Goat-basket; [Greek: aigospyris].

[76] _Pentaspyris_ = Basket with five feet; [Greek: penta], [Greek: spyris].

[77] _Zygospyris_ = Bilocular basket, with paired halves; [Greek: zyga], [Greek: spyris].

[78] _Elaphospyris_ = Deer-basket; [Greek: elaphos], [Greek: spyris].

[79] _Taurospyris_ = Bull-basket; [Greek: tauros], [Greek: spyris].

[80] _Therospyris_ = Basket with four feet, like a beast; [Greek: thêr], [Greek: spyris].

[81] _Petalospyris_ = Leaf-basket; [Greek: petalos], [Greek: spyris].

[82] _Anthospyris_ = Flower-basket; [Greek: anthos], [Greek: spyris].

[83] _Ceratospyris_ = Horned basket; [Greek: keras], [Greek: spyris].

[84] _Gorgospyris_ = Medusiform basket; [Greek: gorgô], [Greek: spyris].

[85] _Circospyris_ = Basket with a ring; [Greek: kirkos], [Greek: spyris].

[86] _Dictyospyris_ = Net-basket; [Greek: diktyon], [Greek: spyris].

[87] _Tholospyris_ = Basket with a cupola; [Greek: tholos], [Greek: spyris].

[88] _Lophospyris_ = Basket with a crest; [Greek: lophos], [Greek: spyris].

[89] _Sepalospyris_ = Basket with leaves; [Greek: sêpalon], [Greek: spyris].

[90] _Tiarospyris_ = Basket with a cap; [Greek: tiara], [Greek: spyris].

[91] _Pylospyris_ = Basket with gates; [Greek: pylê], [Greek: spyris].

[92] _Acrospyris_ = Basket with an apical spine; [Greek: akra], [Greek: spyris].

[93] _Phormospyris_ = Wicker-basket; [Greek: phormos], [Greek: spyris].

[94] _Patagospyris_ = Basket with a patagium; [Greek: patageion], [Greek: spyris].

[95] _Rhodospyris_ = Rose-basket; [Greek: rhodon], [Greek: spyris].

[96] _Desmospyris_ = Basket with a band or string; [Greek: desmos], [Greek: spyris].

[97] _Androspyris_ = Man-like wicker basket; [Greek: anêr], [Greek: spyris].

[98] _Lamprospyris_ = Splendid wicker-basket; [Greek: lampros], [Greek: spyris].

[99] _Amphispyris_ = Basket with a cap on both sides; [Greek: amphi], [Greek: spyris].

[100] _Tricolospyris_ = Wicker-basket with three joints; [Greek: trikôlos], [Greek: spyris].

[101] _Perispyris_ = Wicker-basket surrounded by an envelope; [Greek: peri], [Greek: spyris].

[102] _Sphærospyris_ = Spherical wicker-basket; [Greek: sphaira], [Greek: spyris].

[103] _Nephrospyris_ = Kidney-shaped basket; [Greek: nephros], [Greek: spyris].

[104] _Botryopera_ = Basket with grapes; [Greek: botrys], [Greek: pêra].

[105] _Cannobotrys_ = Grape with tubes; [Greek: kanna], [Greek: botrys].

[106] _Acrobotrys_ = Perfect grape; [Greek: akros], [Greek: botrys].

[107] _Botryocella_ = Grape-pinnace; [Greek: botrys], [Greek: kella].

[108] _Lithobotrys_ = Stone grape; [Greek: lithos], [Greek: botrys].

[109] _Botryocyrtis_ = Basket with grapes; [Greek: botrys], [Greek: kyrtis].

[110] _Pylobotrys_ = Grape with an aperture; [Greek: pylê], [Greek: botrys].

[111] _Botryocampe_ = Caterpillar with a grape; [Greek: botrys], [Greek: kampê]

[112] _Phormobotrys_ = Grape basket; [Greek: phormos], [Greek: botrys].

[113] _Tripocalpis_ = Urn with three feet; [Greek: tripous], [Greek: kalpis].

[114] _Tripodonium_ = Shell with three feet.

[115] _Tripterocalpis_ = Urn with three wings; [Greek: tripteros], [Greek: kalpis].

[116] _Trissopilium_ = Small hat with three wings; [Greek: trissos], [Greek: pilion].

[117] _Archipilium_ = Primordial hat; [Greek: archipilion].

[118] _Tripilidium_ = Small hat with three feet; [Greek: tria], [Greek: pilidion].

[119] _Tripodiscium_ = Shell with three small feet; [Greek: tria], [Greek: podiskion].

[120] _Tridictyopus_ = Shell with three lattice-feet; [Greek: tria], [Greek: diktyon], [Greek: pous].

[121] _Euscenium_ = Nice small tent; [Greek: eu], [Greek: skênion].

[122] _Cladoscenium_ = Small tent with branched axis; [Greek: klados], [Greek: skênion].

[123] _Archiscenium_ = Primordial tent; [Greek: archi], [Greek: skênion].

[124] _Pteroscenium_ = Small tent with wings; [Greek: pteron], [Greek: skênion].

[125] _Peridium_ = Small pouch; [Greek: pêridion].

[126] _Archipera_ = Primordial pouch; [Greek: archi], [Greek: pêra].

[127] _Archibursa_ = Primordial bottle; [Greek: archi], [Greek: byrsa].

[128] _Bathropyramis_ = Pyramid with ladders; [Greek: bathron], [Greek: pyramis].

[129] _Cinclopyramis_ = Lattice-pyramid; [Greek: kinklis], [Greek: pyramis].

[130] _Peripyramis_ = Pyramid with an envelope; [Greek: peri], [Greek: pyramis].

[131] _Litharachnium_ = Spider-web of silex; [Greek: lithos], [Greek: arachnion].

[132] _Cladarachnium_ = Spider-web with branched threads; [Greek: klados], [Greek: arachnion].

[133] _Cystophormis_ = bladder-basket; [Greek: kystê], [Greek: phormis].

[134] _Haliphormis_ = Sea-basket; [Greek: hals], [Greek: phormis].

[135] _Archiphormis_ = Primordial-basket; [Greek: archi], [Greek: phormis].

[136] _Halicalyptra_ = Sea-veil; [Greek: hals], [Greek: kalyptra].

[137] _Carpocanistrum_ = Small fruit-basket; [Greek: karpos], [Greek: kanistron].

[138] _Arachnocalpis_ = Urn enveloped by spider's web; [Greek: arachnê], [Greek: kalpis].

[139] _Phænocalpis_ = Urceolate shell; [Greek: phaina], [Greek: kalpis].

[140] _Phænoscenium_ = Tent-shaped shell; [Greek: phaina], [Greek: skênion].

[141] _Calpophæna_ = Urceolate shell; [Greek: kalpis], [Greek: phaina].

[142] _Archiphæna_ = Primordial shell; [Greek: archi], [Greek: phaina].

[143] _Cornutella_ = Small horn; diminutive of cornu.

[144] _Cornutanna_ = Horn-shaped; _Cornuta_.

[145] _Archicorys_ = Principal helm; [Greek: archikorys].

[146] _Cyrtocalpis_ = Basket-urn or wicker-pitcher; [Greek: kyrtos], [Greek: kalpis].

[147] _Mitrocalpis_ = Turban basket; [Greek: mitra], [Greek: kalpis].

[148] _Spongocyrtis_ = Spongy basket; [Greek: spongos], [Greek: kyrtis].

[149] _Halicapsa_ = Sea-capsule; [Greek: hals], [Greek: kapsa].

[150] _Archicapsa_ = Primordial capsule; [Greek: archikapsa].

[151] _Dictyophimus_ = Net goblet; [Greek: diktyon], [Greek: phimos].

[152] _Tripocyrtis_ = Basket with a tripod; [Greek: tripos], [Greek: kyrtis].

[153] _Sethopilium_ = Small fenestrated hat; [Greek: sêthô], [Greek: pilion].

[154] _Lithomelissa_ = Stone bee; [Greek: lithos], [Greek: melissa].

[155] _Psilomelissa_ = Smooth bee; [Greek: psilos], [Greek: melissa].

[156] _Spongomelissa_ = Spongy bee; [Greek: spongos], [Greek: melissa].

[157] _Clathrocanium_ = Basket of network; [Greek: klêthra], [Greek: kaneon].

[158] _Lamprodiscus_ = Splendid disk; [Greek: lampros], [Greek: diskos].

[159] _Lampromitra_ = Splendid turban; [Greek: lampros], [Greek: mitra].

[160] _Callimitra_ = Beautiful turban; [Greek: kallis], [Greek: mitra].

[161] _Clathromitra_ = Lattice-turban; [Greek: klêthra], [Greek: mitra].

[162] _Clathrocorys_ = Lattice-helmet; [Greek: klêthra], [Greek: korys].

[163] _Eucecryphalus_ = Nice net-cap, [Greek: eu], [Greek: kekryphalos].

[164] _Amphiplecta_ = Shell at both poles open, with framework around; [Greek: amphiplêkta].

[165] _Lychnocanium_ = Lantern-basket: [Greek: lychnos], [Greek: kaneon].

[166] _Lychnodictyum_ = Lantern with network; [Greek: lychnos], [Greek: diktyon].

[167] _Sethopera_ = Sieve-pouch; [Greek: sêthô], [Greek: pêra].

[168] _Lithopera_ = Stone-pouch; [Greek: lithos], [Greek: pêra].

[169] _Micromelissa_ = Small bee; [Greek: mikros], [Greek: melissa].

[170] _Peromelissa_ = Pouch-bee; [Greek: pêra], [Greek: melissa].

[171] _Sethomelissa_ = Sieve-bee; [Greek: sêthô], [Greek: melissa].

[172] _Tetrahedrina_ = Small tetrahedron; [Greek: tetraedron].

[173] _Sethochytris_ = Sieve-pot; [Greek: sêthô], [Greek: chytris].

[174] _Clathrolychnus_ = Fenestrated lantern; [Greek: klêthra], [Greek: lychnos].

[175] _Sethophormis_ = Sieve-basket; [Greek: sêthô], [Greek: phormis].

[176] _Sethamphora_ = Sieve-pitcher; [Greek: sêthô], [Greek: amphoreus].

[177] _Sethopyramis_ = Sieve-pyramid; [Greek: sêthô], [Greek: pyramis].

[178] _Plectopyramis_ = Woven pyramid; [Greek: plektos], [Greek: pyramis].

[179] _Spongopyramis_ = Spongy pyramid; [Greek: spongos], [Greek: pyramis].

[180] _Acanthocorys_ = Spiny Helmet; [Greek: akantha], [Greek: korys].

[181] _Arachnocorys_ = helmet with a cobweb; [Greek: arachnê], [Greek: korys].

[182] _Anthocyrtoma_ = Flower-arch; [Greek: anthos], [Greek: kyrtôma].

[183] _Anthocyrtis_ = Flower-basket; [Greek: anthos], [Greek: kyrtis].

[184] _Anthocyrtium_ = Flower-basket; [Greek: anthos], [Greek: kyrtion].

[185] _Anthocyrtidium_ = Small flower-basket; [Greek: anthos], [Greek: kyrtidion].

[186] _Carpocanium_ = Fruit-basket; [Greek: karpos], [Greek: kaneon].

[187] _Sethophæna_ = Sieve-shell; [Greek: sêthô], [Greek: phaina].

[188] _Clistophæna_ = Closed shell; [Greek: kleistos], [Greek: phaina].

[189] _Sethoconus_ = Sieve-cone; [Greek: sêthô], [Greek: kônos].

[190] _Periarachnium_ = Shell enveloped by cobweb; [Greek: peri], [Greek: arachnion].

[191] _Sethocephalus_ = Sieve-head; [Greek: sêthô], [Greek: kephalê].

[192] _Sethocyrtis_ = Sieve-basket; [Greek: sêthô], [Greek: kyrtis].

[193] _Sethocorys_ = Sieve-helmet; [Greek: sêthô], [Greek: korys].

[194] _Lophophæna_ = Shell with a top-knot; [Greek: lophos], [Greek: phainô].

[195] _Dictyocephalus_ = Latticed head; [Greek: diktyon], [Greek: kephalê].

[196] _Sethocapsa_ = Sieve-capsule; [Greek: sêthô], [Greek: kapsa].

[197] _Dicolocapsa_ = Two-jointed capsule; [Greek: dikôlos], [Greek: kapsa].

[198] _Cryptocapsa_ = Hidden capsule; [Greek: kryptos], [Greek: kapsa].

[199] _Pterocorys_ = Helmet with wings; [Greek: pteron], [Greek: korys].

[200] _Theopilium_ = Divine hat; [Greek: theos], [Greek: pilion].

[201] _Corocalyptra_ = Coif or hood of a girl; [Greek: korê], [Greek: kalyptra].

[202] _Dictyoceras_ = Reticulated horn; [Greek: diktyon], [Greek: kera].

[203] _Pteropilium_ = Small hat with wings; [Greek: pteron], [Greek: pilion].

[204] _Theopodium_ = Divine foot; [Greek: theos], [Greek: podion].

[205] _Pterocanium_ = Basket with wings; [Greek: pteron], [Greek: kaneon].

[206] _Pterocodon_ = Bell with wings; [Greek: pteron], [Greek: kôdôn].

[207] _Dictyocodon_ = Net-bell; [Greek: diktyon], [Greek: kôdôn].

[208] _Pleuropodium_ = Shell with ribs and feet; [Greek: pleura], [Greek: podion].

[209] _Podocyrtis_ = Basket with feet; [Greek: pous], [Greek: kyrtis].

[210] _Thyrsocyrtis_ = Basket with a thyrsus or apical rod; [Greek: thyrsos], [Greek: kyrtis].

[211] _Dictyopodium_ = Shell with latticed feet; [Greek: diktyon], [Greek: podion].

[212] _Lithornithium_ = Siliceous bird; [Greek: lithos], [Greek: ornithion].

[213] _Sethornithium_ = Latticed bird; [Greek: sêthô], [Greek: ornithion].

[214] _Theopera_ = Divine pouch; [Greek: theos], [Greek: pêra].

[215] _Rhopalocanium_ = Basket with clubs; [Greek: rhopalon], [Greek: kaneon].

[216] _Rhopalatractus_ = Spindle with clubs; [Greek: rhopalon], [Greek: atraktos].

[217] _Lithochytris_ = Pot of silex; [Greek: lithos], [Greek: chytris].

[218] _Theophormis_ = Divine basket; [Greek: theos], [Greek: phormis].

[219] _Phormocyrtis_ = Plaited basket; [Greek: phormos], [Greek: kyrtis].

[220] _Alacorys_ = Wing-helmet.

[221] _Cycladophora_ = Bearing a female robe; [Greek: kyklas], [Greek: phoros].

[222] _Calocyclas_ = Beautiful female robe; [Greek: kalos], [Greek: kyklas].

[223] _Clathrocyclas_ = Fenestrated female robe; [Greek: klêthra], [Greek: kyklas].

[224] _Lamprocyclas_ = Splendid female robe; [Greek: lampros], [Greek: kyklas].

[225] _Diplocyclas_ = Female robe with a double girdle; [Greek: diploos], [Greek: kyklas].

[226] _Hexalatractus_ = Spindle with six wings; [Greek: hexala], [Greek: atraktos].

[227] _Theophæna_ = Divine shell; [Greek: theos], [Greek: phaina].

[228] _Theocalyptra_ = Divine veil; [Greek: theos], [Greek: kalyptra].

[229] _Cecryphalium_ = Net-cap; [Greek: kekryphalion].

[230] _Theoconus_ = Divine cone; [Greek: theos], [Greek: kônos].

[231] _Lophoconus_ = Cone with a crest; [Greek: lophos], [Greek: kônos].

[232] _Theocyrtis_ = Divine basket; [Greek: theos], [Greek: kyrtis].

[233] _Theosyringium_ = Divine tube; [Greek: theos], [Greek: syringion].

[234] _Lophocyrtis_ = Basket with a crest; [Greek: lophos], [Greek: kyrtis].

[235] _Tricolocampe_ = Caterpillar with three joints; [Greek: tris], [Greek: kôlon], [Greek: kampê].

[236] _Theocorys_ = Divine helmet; [Greek: theos], [Greek: korys].

[237] _Axocorys_ = Helmet with an internal axis; [Greek: axis], [Greek: korys].

[238] _Lophocorys_ = Helmet with a top crest; [Greek: lophos], [Greek: korys].

[239] _Theocampe_ = Divine caterpillar; [Greek: theos], [Greek: kampê].

[240] _Theocapsa_ = Divine capsule; [Greek: theos], [Greek: kapsa].

[241] _Tricolocapsa_ = Three-jointed capsule; [Greek: trikôlon], [Greek: kapsa].

[242] _Phrenocodon_ = Bell with diaphragm; [Greek: phrên], [Greek: kôdôn].

[243] _Stichopilium_ = Hat with a row of joints; [Greek: stichos], [Greek: pilion].

[244] _Artopilium_ = Loaf-hat; [Greek: artos], [Greek: pilion].

[245] _Pteropilium_ = Winged hat; [Greek: pteron], [Greek: pilion].

[246] _Stichocampe_ = Caterpillar with a row of joints; [Greek: stichos], [Greek: kampê].

[247] _Stichopterium_ = Row-wing; [Greek: stichos], [Greek: pterion].

[248] _Podocampe_ = Caterpillar with feet; [Greek: pous], [Greek: kampê].

[249] _Stichopodium_ = Row-foot; [Greek: stichos], [Greek: podion].

[250] _Stichopera_ = Row-pouch; [Greek: stichos], [Greek: pêra].

[251] _Cyrtopera_ = Basket-pouch; [Greek: kyrtos], [Greek: pêra].

[252] _Artopera_ = Bread-pouch; [Greek: artos], [Greek: pêra].

[253] _Stichophormis_ = Row-basket; [Greek: stichos], [Greek: phormis].

[254] _Phormocampe_ = Latticed caterpillar; [Greek: phormos], [Greek: kampê].

[255] _Artophormis_ = Bread-basket; [Greek: artos], [Greek: phormis].

[256] _Cyrtophormis_ = Plaited-basket; [Greek: kyrtos], [Greek: phormis].

[257] _Artophæna_ = Bread-shell; [Greek: artos], [Greek: phaina].

[258] _Stichophæna_ = Row-shell; [Greek: stichos], [Greek: phaina].

[259] _Lithostrobus_ = Cone of silex; [Greek: lithos], [Greek: strobos].

[260] _Dictyomitra_ = Net-cap; [Greek: diktyon], [Greek: mitra].

[261] _Stichocorys_ = Row-helmet; [Greek: stichos], [Greek: korys].

[262] _Artostrobus_ = Bread-cone; [Greek: artos], [Greek: strobos].

[263] _Lithomitra_ = Stone-cap; [Greek: lithos], [Greek: mitra].

[264] _Eucyrtidium_ = Nice small basket; [Greek: eu], [Greek: kyrtidion].

[265] _Eusyringium_ = Nice small tube; [Greek: eu], [Greek: syringion].

[266] _Siphocampe_ = Caterpillar with a tube; [Greek: siphôn], [Greek: kampê].

[267] _Lithocampe_ = Stone-caterpillar; [Greek: lithos], [Greek: kampê].

[268] _Spirocyrtis_ = Spiral basket; [Greek: speira], [Greek: kyrtis].

[269] _Spirocampe_ = Spiral caterpillar; [Greek: speira], [Greek: kampê].

[270] _Cyrtocapsa_ = Basket-capsule; [Greek: kyrtos], [Greek: kapsa].

[271] _Stichocapsa_ = Jointed capsule; [Greek: stichos], [Greek: kapsa].

[272] _Artocapsa_ = Bread-shaped capsule; [Greek: artos], [Greek: kapsa].

[273] Ueber die Phæodarien, eine neue Gruppe kieselschaliger mariner Rhizopoden, _Sitzungsb. med.-nat. Gesellsch. Jena_, December 12, 1879, pp. 3, 4.

[274] _Phæocolla_ = Brown jelly; [Greek: phaios], [Greek: kolla].

[275] _Phæodina_ = Provided with brown pigment; [Greek: phaiôdion].

[276] _Cannobelos_ = Bearing hollow tubular arrows; [Greek: kanna], [Greek: belos].

[277] _Cannorrhaphis_ = Bearing hollow tubular needles; [Greek: kanna], [Greek: rhaphis].

[278] _Catinulus_ = Small cup or dish.

[279] _Mesocena_ = Hollow in the centre, annular; [Greek: meson], [Greek: kenos].

[280] _Dictyocha_ = Net-possessing; [Greek: diktyon], [Greek: echô].

[281] _Distephanus_ = Double corona; [Greek: distephanos].

[282] _Cannopilus_ = Hat with tubes; [Greek: kanna], [Greek: pilos].

[283] _Aulactinium_ = With radial tubes; [Greek: aulos], [Greek: achtis].

[284] _Aulacantha_ = Tubular spine; [Greek: aulos], [Greek: akantha].

[285] _Aulographis_ = Tubular style; [Greek: aulos], [Greek: graphis].

[286] _Auloceros_ = Tubular horn; [Greek: aulos], [Greek: kerôs].

[287] _Aulospathis_ = Tube with whirls; [Greek: aulos], [Greek: spathis].

[288] _Aulodendron_ = Tubular tree; [Greek: aulos], [Greek: dendron].

[289] _Orona_ = Hilly or tuberculate shell; [Greek: oros], [Greek: ônê].

[290] _Orosphæra_ = Sphere with hilly elevation; [Greek: oros], [Greek: sphaira].

[291] _Oroscena_ = Shell with tent-shaped elevations; [Greek: oros], [Greek: skênê].

[292] In the plate the number is omitted by mistake. The figure is above in the middle.

[293] _Oroplegma_ = Hilly shell of framework; [Greek: oros], [Greek: plegma].

[294] _Sagena_ = Drag-net; [Greek: sagênê].

[295] _Sagosphæra_ = Spherical armour; [Greek: sagê], [Greek: sphaira].

[296] _Sagoscena_ = Armour with tents; [Greek: sagê], [Greek: skênê].

[297] _Sagenoscena_ = Net with tents; [Greek: sagênê], [Greek: skênê].

[298] _Sagmarium_ = Covering of a shield, armour; [Greek: sagmarion].

[299] _Sagmidium_ = Small armour, military clock; [Greek: sagmidion].

[300] _Sagoplegma_ = Armour of framework; [Greek: sagê], [Greek: plegma].

[301] _Aularia_ = Tubular shell; [Greek: aularia].

[302] _Aulosphæra_ = Tubular sphere; [Greek: aulos], [Greek: sphaira].

[303] _Auloscena_ = Tubular tent; [Greek: aulos], [Greek: skênê].

[304] _Auloplegma_ = Tubular framework; [Greek: aulos], [Greek: plegma].

[305] _Aulophacus_ = Tubular lens; [Greek: aulos], [Greek: phakos].

[306] _Aulatractus_ = Spindle composed of tubes; [Greek: aulos], [Greek: atraktos].

[307] _Aulonia_ = Tubular object; [Greek: aulos], [Greek: ônion].

[308] _Aulastrum_ = Tubular star; [Greek: aulos], [Greek: astron].

[309] _Aulodictyum_ = Tubular net; [Greek: aulos], [Greek: diktyon].

[310] _Cannosphæra_ = Sphere with tubules; [Greek: kanna], [Greek: sphaira].

[311] _Coelacantha_ = Hollow spine; [Greek: koilos], [Greek: akantha].

[312] _Lithogromia_ = Siliceous _Gromia_.

[313] _Entocannula_ Shell with an internal tube.

[314] _Pharyngella_ = Shell with an internal pharynx.

[315] _Porcupinia_, in memory of H.M.S. "Porcupine" by which the first British deep-sea explorations were carried out during the years 1869 and 1870.

[316] _Cortinetta_ = Diminutive of _Cortina_.

[317] _Medusetta_ = Small Medusa.

[318] _Euphysetta_ = Diminutive of _Euphysa_ (a Medusa).

[319] _Gazelletta_ = Named in memory of the German ship "Gazelle," which was engaged in deep-sea soundings during the years 1874 to 1876, under the command of Captain Schleinitz (Naturalist, Professor Studer).

[320] _Gorgonetta_ = Diminutive of _Gorgo_, Medusa.

[321] _Polypetta_ = Diminutive of _Polypus_.

[322] _Castanarium_ = Shell similar to a chestnut, _Castanea_.

[323] _Castanella_ = Diminutive of _Castanea_.

[324] _Castanidium_ = Small chestnut; [Greek: kastanidion].

[325] _Castanissa_ = Diminutive of _Castanea_.

[326] _Castanopsis_ = Shell similar to a chestnut; [Greek: kastanon], [Greek: opsis].

[327] _Castanura_ = Chestnut with tails; [Greek: kastanon], [Greek: oura].

[328] _Circoporus_ = Shell with circles of pores; [Greek: kirkos], [Greek: poros].

[329] _Circospathis_ = Shell with verticils around the spines; [Greek: kirkos], [Greek: spathis].

[330] _Circogonia_ = Polyhedron with circles of pores; [Greek: kirkos], [Greek: gônia].

[331] _Circorrhegma_ = Shell with circles of fissures; [Greek: kirkos], [Greek: rhêgma].

[332] _Circostephanus_ = Shell with circular coronets; [Greek: kirkos], [Greek: stephanos].

[333] _Tuscarora_, named from the American ship "Tuscarora," commanded by Captain Belknap, which made a splendid series of deep-sea soundings in the Pacific Ocean in 1875.

[334] _Tuscarusa_, derivation from _Tuscarora_.

[335] _Tuscaridium_, derivation from _Tuscarora_.

[336] _Concharium_ = Small mussel; [Greek: koncharion].

[337] _Conchasma_ = Bivalved shell-fish; [Greek: konchasma].

[338] _Conchellium_ = Small bivalved mussel; [Greek: konchellion].

[339] _Conchidium_ = Similar to a bivalved mollusc; [Greek: konchidion].

[340] _Conchonia_ = Bivalved shell like a mussel; [Greek: konchê], [Greek: onia].

[341] _Conchopsis_ = Similar to a bivalved shell-fish or mussel; [Greek: konchê], [Greek: opsis].

[342] _Conchoceras_ = Mussel with horns; [Greek: konchê], [Greek: keras].

[343] _Coelodoras_ = Hollow spear; [Greek: koilos], [Greek: doras].

[344] _Coelodendrum_ = Hollow tree; [Greek: koilos], [Greek: dendron].

[345] _Coelodrymus_ = Forest of hollow trees, [Greek: koilos], [Greek: drymos].

[346] _Coelodasea_ = Hollow thicket, [Greek: koilos], [Greek: dasea].

[347] _Coelotholus_ = Hollow cupola; [Greek: koilos], [Greek: tholos].

[348] _Coelothauma_ = Hollow wonder; [Greek: koilos], [Greek: thauma]

[349] _Coelothamnus_ = Hollow thicket; [Greek: koilos], [Greek: thamnos]

[350] _Coelographis_ = Hollow style; [Greek: koilos], [Greek: graphis].

[351] _Coelospathis_ = Hollow whorl; [Greek: koilos], [Greek: spathis].

[352] _Coelodecas_ = Shell with ten hollow styles; [Greek: koilos], [Greek: dekas].

[353] _Coelostylus_ = Hollow style; [Greek: koilos], [Greek: stylos].

[354] _Coeloplegma_ = Hollow framework; [Greek: koilos], [Greek: plegma].

[355] _Coelagalma_ = Hollow ornament: [Greek: koilos], [Greek: agalma].

* * * * *

Corrections made to printed text

Page 920: (The different genera of) 'Plectanida' corrected from 'Plectonida'.

Page 951, Cortina dendroides, feet: '0.15 to 0.2' corrected from '01.5 to 0.2'.

Page 964, Cortiniscus tetrapylaris, height: '0.08 to 0.12' corrected from '0.08 to 0.012'.

Page 1029, Tripospyris furcata: (Facial and occipital) 'plates' corrected from 'faces' (as adjoining species).

Page 1056, Elaphospyris heptaceros, horns: '0.08' corrected from '0.008' ("as long as the shell").

Page 1069, Ceratospyris ramosa, author: 'Ceratospyris' corrected from 'Ceratopyris'.

Page 1138, Tripterocalpis, definition: 'Tripocalpis' corrected from 'Tripodocalpis'.

Page 1181, Cornutella stiligera, dimensions: '0.03 to 0.04 broad' corrected from '0.03 to 0.04 long' (as adjoining species).

Page 1220, Clathrocorys murrayi, thorax length: '0.04' corrected from '0.0.04'.

Page 1237, Peromelissa calva, thorax length: '0.07' corrected from '0.7' ("little larger than the cephalis").

Page 1260, Plectopyramis polypleura, thorax: '0.24 broad' corrected from '0.24 long' (as adjoining species).

Page 1338, Podocyrtis conica, breadth a: '0.03' corrected from '00.3'.

Page 1343, Podocyrtis hexagonalis, breadth b: '0.11' corrected from '0.011'.

Page 1352, Dictyopodium eurylophus, author: 'Dictyopodium' corrected from 'Dictopodium'.

Page 1355, Lithornithium trochilus, length (b): '0.05' corrected from '0.5'.

Page 1378, Cycladophora enneapleura: 'Cycladophora gigas' corrected from 'Clycladophora gigas'.

Page 1385, Calocyclas monumentum, length (c): '0.06' corrected from '0.6'.

Page 1387, Clathrocyclas domina: 'peristome' corrected from 'persistome'.

Page 1397, Theocalyptra veneris: 'Eucecryphalus' corrected from 'Eucephryphalus'.

Page 1415, Theocorys turgidula, length (b): '0.05' corrected from '0.005'.

Page 1415, Theocorys cretica, length (a): '0.02' corrected from '0.2'.

Page 1417, Eucyrtidium attenuatum, dimensions: 'breadth' inserted.

Page 1444, Stichocampe convergens, length of each joint: '0.035' corrected from '0.35'.

Page 1547, first paragraph: 'Thalassoplancta' corrected from 'Thallassoplancta'.

Page 1555, Mesocena diodon: 'Ehrenberg, 1854' corrected from 'Ebrenberg, 1854'.

Page 1572, The distal ends of the radial tubes: 'Auloceros' corrected from 'Auloceras'.

Ib., The central capsule: 'Aulosphærida' corrected from 'Aulasphærida'.

Page 1573, second paragraph: 'Thalassicolla nucleata' corrected from 'Thallassicolla nucleata'.

Page 1574, first paragraph: 'Aulographida' corrected from 'Aulagraphida'.

Page 1591, The lattice-shell: 'Cenosphæra' corrected from 'Cenosphera'.

Page 1593, Orosphærida, central capsule: (rarely less than) '0.12' corrected from '1.2'.

Page 1595, Orosphæra foveolata, length of spines: '0.5' corrected from '0.05' ("half as long as the radius of the shell").

Page 1607, Sagosphæra penicilla, reference to 'Sagenoscena penicillata' corrected from 'Sagenoscena pencillata'.

Page 1658, Challengeron moseleyi, larger spines: '0.06' corrected from '0.6' ("about as long as the radius").

Page 1663, Porcupinia aculeata: 'Pharynx' corrected from 'Pharnyx'.

Page 1744, The maximum number of tubes: first occurence of 'Coeloplegmida' corrected from 'Coloeplegmida'.

Index: 'Acrocoronis' corrected from 'Acrocoronia'.

Index, Alacorys: 'guilelmi' corrected from 'gulielmi'.

Index, Amphicraspedum: 'maclaganium' corrected from 'maclagganium' (per text).

Index, Archidiscus: 'dithalamus' corrected from 'dithalamius', and 'trithalamus' from 'trithalamius' (per text).

Index: 'Aulographantha' corrected from 'Aulographanta'.

Index, Aulosphæra diodon: '1623' corrected from '1523'.

Index, Calocyclas amicæ: '1382' corrected from '1282'.

Index, Calocyclas: 'aspasia' corrected from 'aspasiæ'.

Index: 'Conarachnium' corrected from 'Conarachinum'.

Index, Cyphinus: 'dixiphus' corrected from 'dixiphos' (per text).

Index, Hexacolpus: 'dodecodus' corrected from 'dodecotus', per text as signifying 12 teeth (odos).

Index, Lithobotrys galea: '1123' corrected from '1128'.

Index, Panartus profundissimus: '380' corrected from '880'.

Index: 'Phacodiscida' corrected from 'Phacodisida'.

Index, Pityomma: '259' corrected from '299'.

Index, Pylonium nephropylium: '655' corrected from '955'.

Index: 'Sethopera' corrected from 'Sethoptera'

Index, Spongellipsis: '341' corrected from '34'.

Index, Spongocore: 'diplocylindrica' corrected from 'diplocylindrus' (per text).

Index, Aulosphæra diodon: '578' corrected from '378'.

Index, Spongostylus: '149' corrected from '749'.

Index: 'Staurocyclia' corrected from 'Staurocylia'.

Index, Stichoperida: '1447' corrected from '1147'.

Index, Theocampe: 'gemmata' corrected from 'geminata'.

Index, Tuscarora: 'cygnea' corrected from 'cygneum'.

Footnote 188: '[Greek: kleistos]' corrected from '[Greek: sêthô]' (carried down from previous footnote).

Footnote 308: 'Aulastrum' corrected from 'Aulastrus'.