Part 21

POTAMIS or POTAMIDES. Brong. A genus of fresh-water shells resembling Cerithium in the characters of the aperture, but which may be known from that genus by the thick, horny epidermis with which they are coated. P. muricata, fig. 377. (Cerithium, Sow.) We think that these shells should be placed near MELANIA.

POTAMOMYA. A genus of shells resembling Corbula, in every respect except that of being inhabitants of fresh-water. Fig. 498, 499, represents one of these fresh-water Corbulæ.

POTAMOPHILA. Sow. ([Greek: Potamis], _potamis_, river; [Greek: philios], _philios_, choice.) "Conques fluviatiles," Lam.--_Descr._ Thick, equivalve, inequilateral, trigonal, covered with a greenish brown, smooth, horny epidermis; hinge thickened, broad, with one central, notched cardinal tooth in one valve, and two in the other, with indistinct lateral teeth; ligament large, supported on prominent fulcra; muscular impressions two in each valve, sub-orbicular.--_Obs._ The name given to this shell refers to its place of abode, being found in rivers. It is the Venus sub-viridis of some authors, although being a fresh-water shell, and having an incrassated hinge, and a smooth, thick epidermis, it is most distinct from that genus. It is described by Bowdich under the name Megadesma, on account of its large ligament, and by Lamarck under that of Galathæa, a name previously used by him for a genus of Crustacea. P. radiata, fig. 115. Megadesma appears to be the preferable name, since it has the right of priority over Potamophila. It is found in Africa.

PRIAMUS. A genus composed of ACHATINA Priamus, Lam. BUCCINUM Stercus--Pulicum, Chemn. Conch. 9. t. 120. f. 1026-7. This shell is ascertained to belong to a marine mollusc, having a horny operculum, and therefore is justly considered to form a distinct genus, allied to the Buccina and Struthiolariæ. Fig. 545.

PRISODON. Schum. HYRIA, &c. Auct. Fig. 144.

PRODUCED. (_Productus_, prominent.) A term applied to the spire of univalve shells, or to any other prominent portion.

PRODUCTA. Sow. (_Productus_, produced.) _Fam._ Brachiopoda, Lam.--_Descr._ Equilateral, inequivalve, thick, striated; one valve generally convex, with the margin inflected, produced; the other valve flat, or slightly convex, with the margin reflected; hinge rectilinear, transverse.--_Obs._ The peculiarity of this genus, from which it derives its name, is the manner in which the anterior margins of the valves are drawn out and overwrap each other. The genus is only known in a fossil state. Species occur in Mountain Limestone, and Transition Limestone of older date. P. depressa, fig. 206.

PROSERPINA. Gray? Fig. 274, represents a small shell belonging to the Helix tribe, to which it is believed, Mr. Gray has applied the name Proserpina nitida. We do not know how the genus is defined.

PROTO. Defr. A fossil shell resembling TURRITELLA, but having a spiral band reaching to the centre of each valve. P. terebralis, Bl.

PSAMMOBIA. Lam. _Fam._ Nymphacea, Lam.--_Descr._ Transverse, oblong, slightly gaping at both ends; hinge with two cardinal teeth in one valve, one in the other; ligament supported upon a prominent fulcrum; muscular impressions two in each valve, sub-orbicular, distant; palleal impression with a large sinus; epidermis thin.--_Obs._ The genus thus described includes PSAMMOTÆA of Lamarck, which, according to him, only differs in the number of teeth, and which he says are but "Psammobies dégenerées." The difference appears to be accidental. This genus differs from Tellina in not having a posterior fold in the margin. Fig. 100. The species are found in temperate and tropical climates.

PSAMMOCOLA. Bl. ([Greek: psammos], _psammos_, sand; _cola_, an inhabitant.) A name given by De Blainville to shells of the genus PSAMMOBIA, including PSAMMOTÆA of Lamarck.

PSAMMOTÆA. See Lam. PSAMMOBIA.

PSEUDOLIVA. Sw. A genus of "Eburninæ," Sw. thus described: "Shell thick, oval, oliviform, ventricose; spire very short, acute; base with two parallel grooves, one of which forms a notch at the base of the outer lip; suture slightly channelled; inner lip very thick, and turning inwards; aperture with an internal canal. Connects the TURBINELLIDÆ with the VOLUTIDÆ. P. plumbea, Chem. 188. f. 1806, 1807." Sw. p. 306.

PSILOSTOMATA. Bl. The third family of Aporobranchiata, Bl. containing no genera of shells.

PTEROCERAS. Auct. ([Greek: Pteron], _pteron_, a wing; [Greek: keras], _ceras_, horn.) _Fam._ Ailées, Lam.--_Descr._ Turrited, oval, ventricose, thick, tuberculated; spire short; aperture oval, terminating in a lengthened canal at both extremities; outer lip thickened, expanded, produced into horn-shaped, hollow, thickened spires, with an anterior sinus apart from the canal.--_Obs._ This genus, containing the shells commonly called Devil's Claws, Gouty Scorpions, Spiders, &c. is distinguished from Strombus by the digitations of the outer lip. No fossil species are known. Fig. 405, P. aurantiaca.

PTEROCYCLOS. Benson. Syn. B. M. p. 133. A genus formed of species of Cyclostoma, Auct. which have "a groove or hole at the hinder part of the mouth."

PTEROPODA. Lam. ([Greek: Pteron], _pteron_, a wing; [Greek: pous], _pous_, a foot.) The first order of the class Mollusca, Lam. consisting of molluscs whose organs of locomotion consist of a pair of wing-shaped fins. This order contains the genera Hyalæa, Clio, Cleodora, Spiratella, Cymbulia, and Pneumoderma. To which may be added other genera enumerated in explanation of figures 220 to 226. They may be thus distinguished.

1. ATLANTA. Shaped like Nautilus, symmetrical. Fig. 220.

2. SPIRATELLA. Spiral, not symmetrical. Fig. 224.

3. CRESEIS. Straight, thorn-shaped. Fig. 222.

4. VAGINULA. Straight, widened in the centre; apex pointed. Fig. 225.

5. CUVIERIA. The same; apex blunt. Fig. 223.

6. CLEODORA. Aperture with three spines; apex recurved. Fig. 221.

7. HYALÆA. Vaulted, open extremity, three-cornered; apex tridentate. Fig. 226.

PTEROPODA. Bl. The second family of Nucleobranchiata, Bl. the shells of which are described as symmetrical, extremely thin, transparent, longitudinally enrolled, either forwards or backwards. The animals are remarkable for a pair of broad, flat, natatory organs or membranaceous fins, from which the family derives its name. It contains, in the system of De Blainville, the genera Atlanta, Spiratella, and Argonauta, to which may probably be added PHARETRIUM, König; ENTALIS, Defrance.

PULLASTRA. Sow. _Fam._ Conques Marines, Lam.--_Descr._ Equivalve, ovate or oblong, transverse, inequilateral; hinge with three diverging cardinal teeth in each valve, notched at the terminations; muscular impressions two in each valve; palleal impression having a large sinus; ligament external, partly hidden by the dorsal margin.--_Obs._ This genus includes the Venerirupes of Lamarck, and several species of his Veneres, they are found in the sand on the shores of temperate and tropical climates. Fig. 120, P. textile.

PULMONOBRANCHIATA. Bl. The first order of the first section of Paracephalophora monoica, containing the families Limnacea, Auriculacea, and Limacinea.

PULVINITES. Defr. (_Pulvinus_, a cushion.) _Fam._ Malleacea, Lam.--_Descr._ Sub-equivalve, inequilateral, compressed, thin, slightly gaping posteriorly; one valve flat, the other rather concave; hinge linear, short, divided into perpendicular grooves; muscular impressions two, one sub-central, the other above it, nearer the hinge.--_Obs._ This fossil shell is imperfectly known, and it is difficult to give a sufficient reason for separating it from Perna. It comes from the Baculite limestone of Normandy. Fig. 170, P. Adansonii.

PUNCTATED. (_Punctatus_, spotted or dotted.) For example, see Conus Nussatella. Fig. 460.

PUNCTICULIS. Sw. A sub-genus of "Coronaxis," Sw. (Conus) described in Swainson's Malacology, page 311.

PUNCTURELLA. Lowe. CEMORIA, Leach.

PUPA. Auct. _Fam._ Colimacea, Lam.; Limacinea, Bl.--_Descr._ Cylindrical, generally ribbed; spire long, obtuse, composed of numerous slowly increasing whorls; aperture sub-quadrate, rounded anteriorly, entire; outer lip thickened; columella plaited.--_Obs._ This genus is composed of land shells very variable in form, differing from Bulinus in the numerous slowly increasing whorls of the spire, and in the plicæ on the columella, and from Clausilia in the want of a clausium. Britain, Southern Europe, East and West Indies, Mexico, &c. P. Uva. Fig. 291.

PUPELLA. Sw. A sub-genus of Clausilia. Lardn. Cyclop. Malac. p. 334.

PUPILLA. Leach. A sub-genus of Pupa, P. marginata, Auct. (Gray's Turton, p. 196.)

PUPINA. Vignard. MOULINSIA, Grateloup. _Fam._ Colimacea, Lam.--_Descr._ Pupiform, sub-cylindrical; last whorl less than the preceding; surface brilliantly polished; suture of the spire enamelled; aperture circular; peritreme thickened; a notch at the base of the inner lip; operculum horny, spiral.--_Obs._ The species upon which this genus was originally founded, and described in the "Annal des Sciences Naturelles," tome 18, p. 439, (December 1829,) is a small pupiform shell, having nothing to distinguish it but the enamelled suture and the notch in the aperture; characters quite insufficient in themselves for the purpose of generic distinction; at the same time sufficient to lead M. De Ferussac to the suspicion of its having an operculum. The next species, described by Grateloup under the name of Moulinsia Nunezii, (Ann. Soc. Linn. Burd, Nov. 1840), presents more remarkable characters, having the spire turned backwards and the penultimate whorl disproportionately large. Seven additional species have been lately brought to this country from the Philippine Islands by Mr. Cuming. They will be described by the author in the Zoological Proceedings for 1841, and an illustrated monograph of the whole genus is published in the Thesaurus Conchyliorum, Part I, by the Author. It may be observed that in one of the new species, the notch in the peritreme almost disappears, leaving a very slight sinus. Fig. 524, 526, 527, 528.

PURPURA. Auct. ("_The shell-fish from which purple is taken_," Plin.) _Fam._ Purpurifera, Lam. Entomostomata, Bl.--_Descr._ Oval or oblong, thick; spire for the most part short, sometimes rather longer; external surface generally sulcated, granulated, tuberculated or muricated; aperture long, oval, somewhat dilated, emarginated anteriorly; outer lip crenated, acute; columella flattened; operculum horny, with the nucleus lateral, thin towards the columella.--_Obs._ True Purpuræ to be found in the Lamarckian genera Buccinum, Ricinula, and others. They may be generally distinguished by the flatness of the columellar lip, and by the short canal or emargination, which is not reflected or raised, as in Buccinum. The species are very numerous and very variable in form, inhabiting the seas of temperate and tropical climates. The animals secrete a purple liquor, which has been used advantageously for dyeing; the origin of the famous Tyrian dye. Fig. 414, P. persica.

PURPURIFERA. Lam. (_Purpura_, purple; _fero_, to carry.) A family belonging to the second section of Lamarck's order Trachelipoda, the shells of which are described as having a very short recurved, or ascending canal, or else only a notch between the inner and outer lips. The name Purpurifera has been given to the family because the animals which it includes, and particularly the genus Purpura, contain the colouring matter from which the ancients obtained the well known splendid purple. This family contains the following genera.

1. CASSIS. Outer lip thick, reflected, denticulated, canal turned suddenly over the back; spire short; including _Cassidea_ and _Cypræcassis_. Fig. 410 to 412.

2. CASSIDARIA. Canal turned gently upwards. Fig. 407, 408.

3. ONISCIA. Inner lip granulated; canal short. Fig. 409.

4. BUCCINUM. Outer lip thickened not reflected; canal short; including _Cyllene_ and _Phos._ Fig. 416, 421, 422, 425.

5. NASSA. The same, with a notch or tooth at the extremity of the columella; including _Cyclops_. Fig. 423, 424.

6. DOLIUM. Swelled, grooved spirally; outer lip not reflected. Fig. 420.

7. PURPURA. Aperture large; columellar lip flat; including Tritonidea. Fig. 414, 415.

8. MONOCEROS. The same, with a tooth on the outer lip. Fig. 417.

9. CONCHOLEPAS. Patelliform; aperture as large as the shell. Fig. 417.

10. RICINULA. Columellar and outer lips granulated, denticulated, outer lip digitated; including _Tribulus_. Fig. 413.

11. TRICHOTROPIS. Hairs on the epidermis, along the keels. Fig. 429.

12. TEREBRA. Elongated, with a spiral groove near the suture of the whorls. Fig. 428.

13. BULLIA. Short; aperture wide; outer lip marginated. Fig. 427.

14. EBURNA. Like Buccinum, but the outer lip not thickened. Fig. 426.

15. HARPA. With varices at regular intervals. Fig. 419.

PUSIA. Sw. A sub-genus of Tiara (Mitra.) (Sw. Malac. p. 320.)

PUSIODON. Sw. A genus of "Lucerninæ," Sw. (Helix) thus described: "Shell flattened, smooth; the body-whorl large, and much dilated at the aperture; spire small, flat, of three or four contracted whorls; aperture very oblique, sinuated, or obsoletely toothed at the base of the outer lip, which is spreading and sub-reflected; inner lip obsolete; umbilicus open. Zonaria Chemn. 132. f. 1188. auriculata Zool. Ill. I. pl. 6." Sw. Malac. p. 330.

PUSIOSTOMA. Sw. A genus of the family "Columbellinæ." Sw. Thus described: "general form of Columbella, but the outer lip is only toothed in the middle, where it is greatly thickened; inner lip convex between the granular teeth; punctata, E. M. 374. f. 4. mendicaria, 375. f. 10. turturina, 314. f. 2. fulgurans. Lam." Sw. Malac. p. 313.

PUSTULARIA. Sw. A genus of "Cypræinæ," Sw. thus described: "Shell generally marked by elevated pustules; aperture narrow and linear; the extremities more or less produced; the teeth continued beyond, and frequently forming elevated striæ across the lips. P. Cicercula, P. Globulus." Sw. Malac. p. 324.

PYGMÆA. Humph. COLUMBELLA, Auct.

PYLORIDEA. Bl. The ninth family of the order Lamellibranchiata, Bl. the shells of which are described as nearly always regular, rarely otherwise, nearly always equivalve, gaping at both extremities; hinge incomplete, the teeth becoming gradually obsolete; two distinct muscular impressions; palleal impression very flexuous posteriorly. This family is divided into: Section 1. Ligament internal; Pandora, Thracia, Anatina, Mya, Lutricola. Section 2. Ligament external; Psammocola, Soletellina, Solen, Sanguinolaria, Solenocurtus, Solenimya, Panopæa, Glycimeris, Saxicava, Byssomya, Rhomboides, Hiatella, Gastrochæna, Clavagella, Aspergillum.

PYRAMIDAL. (_Pyramidalis._) Resembling a pyramid in form. _Ex._ Cerithium Telescopium, fig. 378.

PYRAMIDELLA. Lam. (_A little pyramid._) _Fam._ Plicacea, Lam. AURICULACEA, Bl.--_Descr._ Pyramidal, smooth, polished; spire long, pointed, composed of numerous whorls; aperture small, modified by the last whorl, rounded anteriorly; outer lip slightly expanded; columella tortuous, with several folds. This is a genus of small, polished, marine shells. Pyramidella Terebellum, fig. 342.

PYRAZUS. Montf. POTAMIS, Brongniart.

PYRELLA. Sw. A genus consisting of Turbinella Spirilla, Auct. and similar species, having a long channel, a pyriform outline, and one strong plait at the base of the columella, the apex of the spire is enlarged. P. Spirillus, fig. 384. (The proper term would be Spirilla.)

PYRIFORM. (_Pyrum_, a pear; _forma_, shape.) Shaped like a pear, i. e. large and rounding at one end, and gradually tapering at the other. _Ex._ Pyrula, fig. 390.

PYRGO. Defr. A genus of microscopic Foraminifera.

PYRGOMA. Auct. ([Greek: Purgos], _pyrgus_, a tower.) _Order_, Sessile Cirripedes, Lam.--_Descr._ Composed of a single conical, hollow paries, with a small aperture closed by an operculum of four valves, and supported upon a cup-shaped base.--_Obs._ The genera into which Leach has divided this genus are Pyrgoma, Adna, and Megatrema; his genera Nobia and Savignium differ in having but two valves for the operculum. Pyrgoma differs from Creusia in having the body of the shell, i. e. the parietal cone, simple, not divided into valves. Fig. 31.

PYRGOPOLON. De Montfort's figure of this genus appears as if it had been drawn from the nucleus of a Belemnite.

PYRULA. Auct. (_A little pear._) _Fam._ Canalifera, Lam. Siphonostomata, Bl.--_Descr._ Thin, oblong, pyriform, ventricose towards the spire, gradually tapering towards the anterior of the aperture, spire short, consisting of few volutions; aperture wide, terminating in a long, narrow, open, canal; columella smooth, elegantly tortuous.--_Obs._ The above description includes all the true Fig shells, which present a most graceful form; the contour partaking of the peculiar curve, called by painters the line of beauty. P. Ficus, fig. 390.

PYRUM. Humph. PYRULA, Lam.

QUADRATE. (_Quadratus._) Square, applied when the outline of shells is formed by nearly straight lines meeting at right angles.

QUADRILATERAL. Four-sided.

QUINQUELOCULINA. D'Orbigny. A genus of microscopic Foraminifera.

RADIATING. (_Radians._) A term applied to the ribs, striæ, bands of colours, &c. when they meet in a point at the umbones of a bivalve shell, and spread out towards the ventral margin.--_Ex._ The bands of colour in Tellina radiata, fig. 105.

RADICATED. (_Radix_, a root.) Attached, and as it were rooted by means of a fibrous byssus.

RADIOLATA. Lam. A family belonging to the order Cephalopoda, Lam. The shells belonging to it are described as discoidal, with the spire central, and the chambers radiating from the centre to the circumference. This family contains the genera Rotalina, Lenticulina, and Placentula.

RADIOLITES. A genus belonging to the family of Rudistes, differing from Sphærulites, in having both the valves more conical.

RADIUS. Montf. A genus composed of OVULUM Volva, Auct. and other similar species, having a long attenuated canal at each extremity. Fig. 442.

RADIX. Montf. A genus composed of species of LIMNÆA, having a short spire and wide aperture.--_Ex._ L. aperta, fig. 309.

RAMIFIED. (_Ramus_, a branch.) Branched out.--_Ex._ The varices of some Murices, &c.

RAMPHIDOMA. Schum. POLLICIPES, Leach.

RAMOSE. (_Ramosus_, branched.) Spread out into branches. _Ex._ Murex inflatus, fig. 395.

RANELLA. Auct. (_Rana_, a frog.) _Fam_. Canalifera, _Lam._ Siphonostomata, Bl.--_Descr._ Oval or oblong, depressed, thick, with two rows of continuous varices, skirting the outline, one on each side; spire rather short, pyramidal, acute, aperture oval, terminating in a canal at each extremity; outer lip thickened within, crenulated, or denticulated, forming an external varix; inner lip spread over a portion of the body whorl.--_Obs._ The shells composing this well-defined genus, are for the most part covered with tuberculations, and granulations, and from the colour and squat shape of some species, have been likened to frogs. The Ranellæ are mostly inhabitants of the East Indian seas. The few fossil species known, occur in the tertiary beds. The two continuous rows of varices skirting the spire, distinguish this genus from Triton, which it nearly approaches, and into which some species run by imperceptible gradations. Fig. 393, 394. Many new species were brought to this country by Mr. Cuming, and are represented in parts 84, 85, 88, 89, 92, 93, of the author's Conchological Illustrations.

RANGIA. Desmoulins. GNATHODON, Gray.

RAPANUS. Schum.? A genus consisting of species of PYRULA, Auct. which are thin, much inflated, with short canals. Fig. 389, P. papyracea.

RAPELLA. Sw. A genus of "Pyrulinæ," Sw. thus described: "Shell ventricose, generally thin, almost globose; the base suddenly contracted, and forming a short canal, the channel almost obsolete; umbilicus large, partly concealed by the inner lip. R. papyracea. En. Méth. 436, f. 1." Sw. p. 307. RAPANUS, Schum. Fig. 389.

RAPHANISTER. Montf. A species of madrepore, described as a shell.

RAPUM. Humph. TURBINELLA, Lam.

RAZOR SHELL. A common name by which shells of the genus Solen, are known in the market.

RECTILINEAR. (_Rectus_, right; _linea_, a line.) In a straight line. _Ex._ The hinge of Byssoarca Noæ, fig. 132.

RECURVED. (_Re_, back; _curvo_, to bend.) Turned backwards; the term, when applied to symmetrical conical univalves, is used to signify that the apex is turned towards the posterior margin, as in Emarginula, fig. 241.

REFLECTED. (_Reflected_, to fold back.) Turned, or folded backwards. _Ex._ The edge of the outer lip in Bulinus, fig. 282, is _reflected_, while that of Cypræa, fig. 445 to 450, is _inflected_.

REMOTE. (_Remotus_, distant.) Remote lateral teeth in a bivalve shell, are those that are placed at a distance from the cardinal teeth. _Ex._ The lateral teeth of Aphrodita, (fig. 123.) are remote; those of Donax, (fig. 108) are near.

RENIELLA. Sw. A sub-genus of Malleus. Lardn. Cyclop. Malac. p. 886. Gray states it to be only a distorted specimen of Vulsella, Syn. B. M. p. 145.

RENIFORM. (_Ren_, a kidney; _forma_, shape.) Shaped like a kidney. _Ex._ The aperture of Ampullaria, fig. 318.

RENULINA. Lam. A genus of microscopic Foraminifera.

REOPHAX. Montf. A genus of microscopic Orthocerata, Bl.

REPENT. (_Repens_, creeping.) A term applied to those shells, which, being attached by the whole length of their shell, give the idea of creeping or crawling. _Ex._ Vermilia, fig. 7.

RETICULATED. (_Reticulatus._) Resembling net-work.

RETIFERA. Bl. The first family of the order Cervicobranchiata, Bl. containing the genus Patella.

REVERSED or SINISTRAL SHELLS, are those in which the aperture is on the left side of the shell, while it is held with the mouth downwards, and towards the observer. _Ex._ Balea, fig. 296. Attached bivalves are said to be reversed, when the left valve is free, instead of the right; a circumstance which sometimes occurs in Chama and Ostrea.

RHEDA. Humph. HYALÆA, Lam.

RHINOCLAVIS. Sw. A genus of "Cerithinæ," Sw. thus described: "channel curved backwards, in an erect position; inner lip very thick, with a tumid margin; pillar generally with a central plait; operculum ear-shaped; lineatum. En. M. 443, fig. 3, Vertagus. Ib. f. 2, subulatum. Lam. No. 23, fasciatum. Mart. 157, f. 1481. obeliscus, En. Méth. 443, f. 4; aluco, Ib. f. 5, (Aberrant,) semi-granosum. Ib. 443, f. 1, asperum. Mart. 157, f. 1483."

RHINOCURUS. Montf. A genus of microscopic Foraminifera.

RHINODOMUS. Sw. A genus of "Scolyminæ," Sw. thus described: No internal groove; shell clavate; the spire longer than, or equal with the aperture; the whorls with ridges or longitudinal varices, and rendered hispid by transverse grooves; inner lip wanting; pillar with a terminal fold; aperture striated; outer lip with a basal sinus. R. senticosus, Chem. tab. 193. f. 1864-1866.