Part 6

ANOMIA. _Fam._ Ostracea, Lam. and Bl.--_Descr._ Irregular, inequivalve, sub-equilateral, foliaceous, pearly within; adhering to marine substances by means of a bony appendage, which passes through a large circular opening in the lower valve; muscular impression divided into three irregular portions; hinge destitute of teeth with a short cartilage.--_Obs._ The Linnæan genus included not only the shells to which the description above given would apply, but also many other genera, such as Crania, Orbicula, Terebratula, &c. which belong to the Brachiopoda, and are perfectly distinct. The Anomiæ are found in Europe, N. America, Moluccas, Philippine Islands, &c. Fig. 186, in the plates, is a somewhat reduced representation of a full grown specimen of A. Ephippium. Fig. 187, the hinge of the under valve, with the bony process. Fig. 188, the hinge showing the opening through which it passes.

ANOSTOMA. See ANASTOMA.

ANSATES. Klein. A genus formed of those species of Patella which have a produced, recurved beak. Helcion, Montf. _Ex._ Patella pellucida, fig. 230.

ANSULUS or ANSYLUS. Mr. Gray conjectures that the name of the genus Ancylus, should be so written.

ANTENOR. Montf. A genus of microscopic Foraminifera.

ANTERIOR. In Bivalves is the side on which the head, or part analogous to the head of the animal lies; it is known in the shell by the umbones, which if turned at all, are turned towards that part. If there be a sinus in the impression of the mantle, it is always on the posterior part of the shell. If the ligament be placed only on one side of the umbones, it is only on the posterior side. The anterior of a _spiral univalve_ is that part of the outer lip which is at the greatest distance from the apex. Of a _symmetrical_ conical univalve such as Patella, it is that part where the head of the animal lies, indicated by the interruption of the muscular impression. Of _cirripedes_, that part where the ciliæ protrude are anterior; of _Brachiopoda_, that part which is farthest from the umbones and which corresponds with the ventral margin in other Bivalves. The anterior of _symmetrical, convolute univalves_, is the outer or dorsal part of the aperture, or that part which is farthest from the spire. Lamarck and other Conchological writers have occasioned much confusion by their errors on this subject; describing the same part of a shell at one time anterior, at another posterior; but generally the reverse of the above arrangement, which is founded upon the natural position of the animal, and generally adopted. The anterior will be indicated by the letter _a_, in figs. 119, 421, 229, 34, 202.

ANTIGONA. Schum. A genus composed of VENUS cancellata, Lam. (fig. 119.) and similar species.

ANTIQUATED. This word, signifying _out of date_, is occasionally used to express that species of composition which constantly occurs in shells, by each fresh deposit or layer of calcareous matter, forming a new margin, which being replaced by its successor, is no longer used as the margin, and is consequently said to be out of date.

APEX. This term does not apply to the natural position of a shell, but is used in a mathematical sense, to indicate the nucleus or first formed part; which may be considered as the point of the spiral cone. From this point, the shell enlarging rapidly or slowly as it descends, takes a spiral, arched, straight, oblique, convolute, or irregularly spiral course. The apex will be indicated by the letter _a_, in fig. 282 and 466.

APERTURE or MOUTH. The entrance to the spiral cavity of univalve shells. The parts of the aperture are separately described, as follows: The inner lip or labium is that part which lies over the preceding whorl of the shell. It terminates anteriorly, or towards the lower part in what is termed the columella, so called because it forms a kind of axis on which the volutions turn. The outer lip, sometimes called the labrum, is on the opposite side, or the farthest from the axis. If the edges of the inner and outer lips unite all round, they are described as composing the peritrême. In fig. 318, the aperture is marked by the letter a.

APHRODITA. Lea. (from [Greek: Aphroditê], Greek name of Venus.) A genus composed of CARDIUM Groenlandicum, Auct. fig. 123*, and other similar species of Cardium, the teeth of which are either wholly wanting, or very indistinct. Northern Ocean.

APICIAL. Belonging to the apex. The apicial extremity of the aperture of a univalve shell, is that which is nearest to the apex of the spire.

APICULUM. Humph. TROCHUS, Lam.

APLEUROTIS. Rafinesque. A genus unfigured and imperfectly described as differing in some respects from Terebratula and other Brachiopodæ.

APLEXUS. Fleming. A genus composed of PHYSA Hypnorum, Drap. &c. and described as having the inner lip simple, and not spread over the body whorl.

APLODON. Rafinesque. A genus proposed to be established at the expense of the genus HELIX, but upon what grounds does not appear from the imperfect description which is unaccompanied by a figure.

APLUSTRE. Schum. A genus formed for the reception of those species of BULLA which have the spire uncovered. _Ex._ Bulla Aplustre, (_aplustre_, a flag.) Auct. fig. 289.

APLYSIA. Linn. (_a_, without; [Greek: Pluô], to wash.) _Fam._ Laplysiens, Lam. Aplysiana, Bl.--_Descr._ Horny, transparent, clypeiform, or shield-shaped, placed horizontally on the back of the animal, with its convex side uppermost; apex slightly incurved.--_Obs._ The animal producing this shell has derived its name from the purplish liquor which it exudes, when disturbed. In contour, it has been fancied to present a certain likeness to a hare crouching, and on this account was called _Lepus marinus_, or sea hare, by the ancients. The shell bears a strong resemblance to Dolabella, which, however, is much thicker, and more testaceous. The species are found in the Mediterranean, European, and West Indian Seas. A. Petersoni, fig. 254.

APLYSIACEA. Bl. The second family of the order Monopleurobranchiata, Bl. The animals composing this family are either destitute of shells, or are provided with internal ones, which are flat, open, oblique, with the apex or nucleus slightly incurved, not distinctly spiral. This family contains the genera, Aplysia and Dolabella. The first sub-spiral, with the apex terminal; shell thin, horny. Fig. 254. The second the same, but thick and shelly. Fig. 255.

APOLLON. Montf. RANELLA Ranina, Auct. Placed by De Blainville in that division of Ranella, which is characterized as being umbilicated. Fig. 393.

APOROBRANCHIATA. Bl. The first order of the second section of Paracephalophora Monoica, Bl. The Thecosmata is the only family of this order containing any approach to shells, these are Hyalæa and Cymbulia.

APORRHAIS. Petiver. A genus formed of ROSTELLARIA Pes-pelicani, _Auct._ (fig. 404) and similar species. Although the shell presents no characters to distinguish it generically from Rostellaria, those who have examined the soft parts are convinced that it is distinct. Of the three species now known and figured in part I. of Thesaurus Conchyliorum, by the Author, one is common on our own coast, and in the Mediterranean; also North America. See ROSTELLARIA.

AQUATIC. A term applied by some authors to those species of Molluscous animals, which inhabit fresh water, either in rivers, or salt water standing pools, as distinguished from the marine or Mollusca. See Fresh-water.

AQUILLUS. Montf. TRITON Lampas, Cutaceus, &c. Auct. Placed by De Blainville in the division of the genus Triton, which is described as having a short spire, being covered with tubercles and umbilicated. Triton Cutaceus, fig. 399.

ARCA. Auct. (Anglicè, a boat.) _Fam._ Arcacea, Lam.--_Descr._ Obliquely transverse, subquadrate, equivalve, or nearly so, inequilateral, thick, ventricose, longitudinally ribbed, dentated near the inner margins; hinge rectilinear, forming a flat, external area, upon which the ligament is spread in cross rows, and having a series of small, regular teeth, extending on both sides of the umbones in each valve; muscular impressions distant.--_Obs._ The shells composing this genus are easily distinguished from those of all other bivalve shells, by the straight, linear row of small, notched teeth, and by the area between the umbones. The genus _Cucullæa_ makes the nearest approach to it in this respect, but it may easily be known from it by the outermost teeth on each side of the row being oblique, and lengthened out; and also by the prominent edge of the muscular impression. These shells are found recent, in various marine localities; fossil, in the tertiary deposits. The Arca Noæ, formerly regarded as the type of this genus, has, with several other species, been separated from it under the name of Bysso-arca, by Swainson, on account of an hiatus in the ventral margin, to admit the passage of a byssus; this is not found in the true Arcæ. The true Arcæ are mostly tropical. Arca Antiquata, fig. 131. Bysso-arca Noæ, 132.

ARCACEA. Lam. A family of the order Conchifera Dimyaria, characterized by a series of teeth placed on the hinge in a line. The genera may be distinguished as follows,

1. ARCA. Hinge straight; valves close. Fig. 131.

2. BYSSO-ARCA. Valves gaping. Fig. 132.

3. CUCULLÆA. Distant teeth oblique; posterior muscular impression prominent. Fig. 133.

4. PECTUNCULUS. Hinge curved. Fig. 134.

5. NUCULA. The same, with a pit in the centre of the hinge, including Myopara and Crenella. Figs. 135 to 137.

6. SOLENELLA. Fresh water, oval; a series of teeth on one side of the hinge, only two or three on the other. Fig. 138.

ARCHAIAS. Montf. A genus of microscopic Foraminifera.

ARCHONTE. Montf. HYALÆA, Auct.

ARCINELLA. Schum. CHAMA Arcinella, Auct.

ARCTICA. Schum. CYPRINA Icelandica, Auct.

ARCUATED. (Arcus, an arch.) Bent in the form of an arch, as Dentalium, fig. 2.

AREA. A flat space or disc, on any part of a shell. As for instance, the triangular space on the hinge of Arca, fig. 132, and Spondylus.

ARENACEOUS. (Arena, sand.) Of a sandy texture, as the sand tubes surrounding the bodies of some of the Annellides, named Arenaria on this account. But the word is more commonly used to intimate the habits of the animal, burrowing with its shell in the sand.

ARETHUSA. Montf. A genus of microscopic Foraminifera.

ARGONAUTA. Auct. Commonly called the "Paper Sailor." _Fam._ Pteropoda, Bl. _Order_ Cephalopoda Monothalamia, Lam.--_Descr._ Light, thin, transparent or nearly so, symmetrically convolute, carinated by a double row of tubercles, terminating smooth or tuberculated ribs radiating towards the centre; aperture large, elongated; peritrême acute, interrupted by the body whorl.--_Obs._ The exquisitely beautiful, light and delicate fabrics included under the above name are inhabited by a molluscous animal named the _Ocythöe_, which is provided with tuberculated arms. These, hanging over the sides of the aperture, give to the whole the appearance of a vessel propelled by oars: a poetical illusion further heightened by the broad, flat membranes of the two arms, which, when vertically expanded, present an idea of sails. Pliny has described the Nautilus (the name has been changed by the moderns) as sailing gracefully on the Mediterranean waters; and Pope has versified the idea in the well known lines

"Learn of the little Nautilus to sail, Spread the thin oar and catch the driving gale."

Scientific men have long been engaged in the interesting discussion, whether the animal really belongs to the shell in which it is found, or whether, having destroyed the rightful owner, it has possessed itself of the "frail bark." It is now, however, proved beyond the shadow of a doubt that the Argonaut is the testaceous part of the Ocythöe, and that the broad membranes which in some representations have been artificially placed as sails, are naturally bent backwards over the shell like the mantle of some other molluscs. The interesting experiments of Madame Power, in the Mediterranean, have contributed very materially to lead the investigations of Naturalists to a satisfactory conclusion. This lady kept a cage under water, in which Argonautæ were bred in great numbers, giving her an opportunity of tracing the gradual development of the shell in all its stages, from the elastic and transparent nucleus to the full grown "Paper Sailor." Fig. 485.

ARIANTA. Leach. A sub-genus of land shells, containing HELIX arbustorum, Auct. (Gray, Turton, p. 137.)

ARION. A genus of slugs which have no shells.

ARROW-HEADS. One of the names by which fossils of the genus Belemnites were formerly known.

ARTEMIS. A genus of bivalve shells, distinguished from those of the genus Venus, by having a rounded, denticular form, and a deep, angular sinus in the palleal impression. This does not appear to me to be a sufficient ground of generic distinction, the palleal impressions of the Veneres being subject to great variations. British, also from West Indies, South America, Australia, &c. A. lincta, fig. 118.

ARTICULATED. (Jointed.) Applied to distinct parts of shells, which are fitted or jointed into each other, as the valves of Chitones and those of Balani. The operculum of Nerita is said to be _articulated_ to the columella, having a small process by which it is as it were locked under the edge. See _Introduction_. The word is also applied to the Cirri, which protrude from the oral openings of Cirripedes.

ARTICULINA. D'Orb. A genus of microscopic Foraminifera.

ASIPHONIBRANCHIATA. Bl. The second order of Paracephalophora Dioica, Bl. Consisting of spiral univalves, which have no notch or canal at the anterior part of the aperture. This order is divided into the families Goniosomata, Cricosomata, Ellipsostomata, Hemicyclostomata, and Oxystomata.

ASPERGILLUM. Lam. (From _Aspergo_, to sprinkle.) _Fam._ Tubicolæ, Lam. Pyloridea, Bl.--_Descr._ The small, equal, equilateral valves are cemented into, so as to form part of, a large tube; the umbones are slightly prominent outside. The tube is elongated, rather irregular, granulated with sandy particles, and terminated at the base by a convex disc, which is perforated by small pores, elongated into tubes round the edge, presenting a resemblance to the spout of a watering pot, whence the name is derived. _Loc._ New Holland, Java, New Zealand, Red Sea. Fig. 44. Aspergillum Vaginiferum.

ASSIMINEA. Leach. _Fam._ Turbinacea, Lam.--_Descr._ Inclining to oval, light, thin, covered with a horny epidermis, spire produced into an acute pyramid; whorls slightly angulated in the centre, rounded beneath; aperture elliptical, slightly modified by the last whorl; inner lip planed; outer lip thin; operculum horny, subspiral. Found in brackish water; one species may be procured abundantly on the muddy shores of the Thames, in Kent. There are also species from Calcutta, China, Tahiti, and Australia. Without comparing the animals, it is difficult to distinguish this genus from some species of Littorina. Fig. 363. A. Grayana.

ASTACOLUS. Montf. A genus of microscopic Foraminifera. CRISTELLARIA Crepidula, Lam.

ASTARTE J. Sowerby. (Name of a Sidonian Goddess, _Ashtaroth_ in Scripture.) _Fam._ Nymphacea, Lam. Genus Crassina, Lam.--_Descr._ Suborbicular, equivalve, inequilateral, thick, compressed; hinge with two solid diverging teeth in the right valve, one tooth and a slight posterior elevation in the left; muscular impressions, two in each valve, uniform, united by a simple palleal impression; ligament external.--_Obs._ This genus differs from Venus, Cytheræa, &c. in not having a posterior sinus in the impression of the mantle. The hinge also differs in having but two cardinal teeth. Astarte differs from Crassatella in having no internal cartilage in the hinge. Some of the species are British, others are from America, and one from Sicily. The fossils occur in Crag, Lower Oolite, &c. Fig. 110. A. Danmoniensis.

ASTROLEPAS. Klein. CORONULA Testudinaria, Auct. CHELONOBIA, Leach. Fig. 15.

ATLANTA. Lesueur. _Fam._ Pteropoda, Lam. and Bl.--_Descr._ Spiral, convolute, transparent, fragile, compressed, with a broad, fimbriated, dorsal keel, and a narrow aperture. This shell, which is called "_corne d'ammon vivant_," is found in the Atlantic. The small Pteropod, figured in Sowerby's Genera as Limacina, belongs to this genus. Atlanta Helicialis, fig. 220.

ATRACTODON. Charlesworth. (Mag. Nat. Hist. 2nd series, Vol. 1. p. 218. ) A genus proposed for the admission of a singular fossil shell, found on the beach at Felix-stone, of which the following are the characters;--fusiform, aperture equalling the spire in length, terminating anteriorly in a slightly recurved canal; columellar lip smooth, curved, thickened posteriorly into a blunt tooth; spire obtuse.--_Obs._ This shell would be a Fusus were it not for the tooth on the posterior extremity of the columellar lip. The only species known is regularly striated in a spiral direction, and named A. Elegans.

ATRYPA, Dalman. A genus of brachiopodous bivalves, distinguished by the valves being nearly equal, and the umbones not separated by an intermediate area. A. reticulata, fig 302.

ATTACHED. Shells are attached to marine substances by various means; in some cases by a _byssus_, or a bunch of tendinous fibres passing through an opening between the valves, which gape at their margins to admit a free passage, as in the genera Byssoarca and Mytilus. In other cases the byssus is of a more compact substance, and passes through a perforation in the shell itself. This is the case with many of the brachiopodous shells, in some species of which the perforation is in the point of the umbones, a specimen of which is represented in the Introduction. This species of attachment does not keep the animal motionless, although it is confined to a particular spot. Other shells are attached by a portion of their own substance, as in Chama, Spondylus, Serpula, &c. in which instances, the attached valve is motionless, and is termed the under valve. The Pedunculated Cirripedes are attached by a tubular tendinous process, called a peduncle.

ATTENUATED. Drawn out, long, thin, tapering, as the extremities of Ovulum Volva, fig. 442.

ATYS. Montf. A generic name including those species of BULLA, which are described as "convolute, with the last whorl covering the rest and hiding the spire, the apex rounded at both ends." Bulla Naucum, Auct. fig. 250.

AURICLE. (A little ear.) See AURICULATED.

AURICULA. Lam. (Dim. from _Auris_ an ear.) _Fam._ Auriculacea. Bl. Colimacea, Lam.--_Descr._ Oval or oblong, cylindrical or conical; aperture long, narrow, generally narrowest in the centre; rounded anteriorly, with two or three strong folds on the inner lip, and the outer lip thickened, reflected or denticulated; spire short, obtuse, epidermis horny, brown.--_Obs._ The above description includes the A. coniformis, f. 298. and several other conical species with narrow apertures which formed the genus _Melampus_, Montf. and _Conovulus_, Lam. The latter author suppressed his genus on ascertaining the Conovuli to be land shells. We exclude, however, the A. Dombeyana, Lam. f. 300. and several similar species, which being more rounded, having thin outer lips and but one fold on the columella, are described under the generic name _Chilina_, Gray. It appears rather doubtful whether the Auriculæ are marine or fluviatile, but the animals appear to be amphibious. The Auriculæ are principally found in Salt Marshes of Tropical climates, some small species are found on the Southern European Coasts, as far north as Britain and south as Tierra del Fuego. The Auriculæ formed a part of the genus Voluta of Linnæus, f. 297. A. Judæ, f. 298. A. Coniformis.

AURICULATED. Some bivalve shells, such as _Pecten_, fig. 171, 172, have a flat, broad, somewhat triangular appendage on one or both sides of the umbones, called an _auricle_, or little _ear_. If on one side only, they are said to be _uni-auriculated_; if on both, they are said to be _bi-auriculated_.

AURICULACEA. Bl. The second family of the order Pulmobranchiata, thus described; "shell thick, solid; aperture more or less oval, always large, rounded anteriorly, and contracted by teeth or folds on the columella." This family is included in the genus Voluta of Linnæus, on account of the plaited columellar lip, a character by which that heterogeneous assemblage of shells is distinguished. It forms part of the family of _Colimacea_, Lam. from which they differ not only in general form, but also in the fact of the animals being partly amphibious, always living (according to De Blainville) on the sea shore, and being occasionally covered with water for a short time. It contains the genera Pedipes, Auricula, Pyramidella.

AURIFERA. Bl. OTION, Auct.

AURIFORM. (From _Auris_, an ear; _forma_, shape.) Ex. _Haliotis_, fig. 338.

AURISCALPIUM. Megerle. ANATINA, Lam.

AVICULA. Lam. (From _Avis_, a bird). _Fam._ Malleacea, Lam. Margaritacea, Bl.--_Descr._ Inequivalve, inequilateral, foliaceous, subquadrate, oblique, pearly; hinge rectilinear, lengthened into auricular appendages, with a small indistinct tooth in each valve, an elongated, marginal, ligamentiferous area, and an hiatus in the left valve, for the passage of a byssus; one circular muscular impression, near the centre of each valve, with a series of smaller ones arranged in a line towards the umbones.--_Obs._ The Meleagrinæ of Lamarck, Margaritiferæ, Schum. included in this description, consist of the more rounded species, and do not present the elegant obliquity of form, nor the wing-like auricles from which the genus Avicula receives its name. The Aviculæ are pearly within. From A. margaritifera, a young specimen of which is figured in the plates, fig. 164, is obtained oriental pearls. This is an example of Meleagrina. A. Hirundo, fig. 163, belongs to the genus Avicula of Lamarck. It is, however, needless to continue the separation. Aviculæ are from E. and W. Indies, Mexico, Coasts of the Pacific, Mediterranean, British Islands, &c. Fossil species occur in the London clay, &c.

AXINUS. J. Sowerby.--_Descr._ Equivalve, transverse; posterior side very short, rounded, with a long ligament, placed in a furrow, extending along the whole edge; anterior side produced, angulated, truncated, with a flattish _lunule_ near the beaks. The late Mr. James Sowerby, who described this shell in the Mineral Conchology, did not consider his genus as established, not having seen the hinge.

AXIS. The imaginary line, round which the whorls of a spiral shell revolve. The extremities of the axis are pointed out in fig. 379, by the letters, _a. a._ See "COLUMELLA."