A Conchological Manual, George Brettingham Sowerby [little readers .TXT] 📗

smooth. We

   have given representations of their different forms as follows: O.

   Ovum, fig. 442. O. verrucosum, (Calpurnus Montf.) fig. 441. O. Volva,

   the weaver's shuttle (Radius, Montf.) fig. 442. O. gibbosum, (Ultimus,

   Montf.) fig. 443.

 

   OXYSTOMATA. Bl. The fifth family of Asiphonibranchiata, Bl. This family

   appears to have been formed for the express purpose of providing a

   place in the system for the genus Janthina, which seems to bear so

   little analogy with other genera of Mollusca, that conchological

   writers have been puzzled to know where to place it.

 

   PACHYLABRA. Sw. PACHYSTOMA, Guild. A sub-genus of Ampullaria, the outer

   lip of which is thickened within. _Ex._ Ampullaria globosa.

 

   PACHYMYA. Sow. ([Greek: pachus], _pachus_, thick, and _Mya_.) _Fam._

   Cardiacea? Lam.--_Descr._ Obliquely elongated, equivalve, thick,

   sub-bilobed, with beaks near the anterior extremity; ligament partly

   immersed attached to prominent fulcra.--_Obs._ This singular fossil is

   shaped like Modiola, but the shell being extremely thick, and the

   ligament attached to a prominent fulcrum, it is difficult to know where

   to place it. Fig. 130, Pachymya Gigas.

 

   PACHYSTOMA. Guild. ([Greek: pachus], _pachus_, thick; [Greek: stoma],

   _stoma_, mouth.) A genus composed of such species of Ampullaria, Auct.

   as have the edge of the aperture thickened and grooved within so as to

   form a sort of ledge upon which the operculum rests. Ampullaria globosa

   and corrugata are examples of this variation. The name Pachylabra is

   given to such species by Swainson, who objects to the above name on

   account of its having been previously used to a genus of fishes. Fig.

   539.

 

   PACHYTOMA. Sw. A sub-genus of Helicina, thus described, "Aperture

   entire; the inner lip very thick; the spiral whorls hardly convex; P.

   occidentalis. Zool. J. iii. 15. f. 6-10. viridis, Zool. Journ. i. pl.

f. 7." Sw. p. 337.

 

   PACLITES. Montf. A genus composed of species of Belemnites, Auct.

   described towards the extremity, with a pore, at the apex, and a

   straight lengthened aperture. _Ex._ B. ungulatus, Bl.

 

   PADOLLUS. Montf. A genus composed of species of HALIOTIS, with a

   strongly marked spiral groove. _Ex._ H. tricostalis, Lam. Fig. 339.

 

   PAGODELLA. Sw. A sub-genus of Trochus, thus described: "Trochiform;

   generally thin, and always not pearlaceous; aperture and pillar

   perfectly united and entire; operculum horny. P. major. Mart. 163. f.

   1541, 1542. tectum-persicum. Ib. f. 1543, 1544." Sw. p. 351.

 

   PALLEAL IMPRESSION. (_Pallium_, a mantle.) The mark or groove formed in

   a bivalve shell by the muscular attachment of the mantle, which, being

   always found near the margin of the shell, is sometimes termed the

   marginal impression. In bivalves with two muscular impressions it

   passes from one to the other. If in passing, it takes a bend inwards

   posteriorly, it is said to be sinuated, and that part is called by Mr.

   Gray, the Siphonal scar.

 

   PALLIOBRANCHIATA. Bl. The first order of the class Acephalophora. Bl.

   The animals of this order are described as more or less compressed,

   included between the two valves of a bivalve shell, one inferior, the

   other superior, joining at the back and opening in front. The

   Palliobranchiata in the system of De Blainville correspond with the

   Brachiopoda in the system of Lamarck, and the shells may be known by

   their being symmetrical. This order contains in the first section of

   symmetrical bivalves, Lingula, Terebratula, Thecidium, Strophomena,

   Plagiostoma, Dianchora and Podopsis: in the second section, Orbicula

   and Crania.

 

   PALMATED. Flattened like a palm, as the fronds or fringes of some

   Murices.

 

   PALMINA. Gray. Differing from OTION in having but one auricle.

 

   PALUDINA. Lam. _Fam._ Peristomata, Lam. Cricostomata, Bl--_Descr._

   Varying in form from oval to globose, in some instances oblong, covered

   with a greenish horny epidermis; spire acute, composed of rounded

   whorls; aperture ovate; peritreme entire, slightly modified by the last

   whorl; operculum horny, concentric. Europe, North America, East Indies,

   China, &c.--_Obs._ The construction of the operculum distinguishes this

   genus of freshwater shells from Valvata and Cyclostoma. The Paludinæ

   are viviparous. Fig. 321. P. Achatina.

 

   PALUDOMUS. Sw. A genus of the family of "Melanianæ," Sw. described as

   differing from Melania in having the spire shorter than the aperture.

   Sw. p. 340.

 

 PANDORA. Brug. _Fam._ Corbulacea, Lam. Pyloridea, Bl.--_Descr._ Thin,

   inequivalve, pearly within, rounded anteriorly, rostrated posteriorly;

   right valve flat with a cardinal tooth, or short rib, and a slit

   containing the cartilage with a narrow plate on the dorsal edge turned

   towards the left valve; left valve concave, with a receptacle for the

   cardinal tooth of the right valve and the internal cartilage; no

   external ligament. Europe, America, Ceylon, &c.--_Obs._ This well known

 genus is in no danger of being confounded with any other shell. Fig.

P. rostrata.

 

   PANOPÆA. Menard. _Fam._ Solenacea, Lam. Pyloridea, Bl.--_Descr._

   Equivalve, inequilateral, oval, gaping at both extremities; hinge with

   an acute cardinal tooth in each valve, and a large callosity near the

   umbones supporting the ligament; muscular impressions two, distant,

   oval; palleal impression with a large sinus. Britain, North America,

   Mediterranean, Australia, &c.--_Obs._ This genus resembles Mya in

   general appearance, but differs in having an external ligament and a

   sharp tooth, instead of the broad spoon-shaped process in the hinge of

   the latter genus. Fig. 65. P. Australis.

 

   PAPER SAILOR. A common name given to the Argonauta.

 

   PAPILLARY. (_Papilla_, a teat.) Shaped like a teat. This term is

   applied by conchologists when the apex of the spire of an univalve

   shell is rounded like a teat and not spiral up to the extreme point; as

   the apex of Cymba, fig. 434.

 

   PAPYRACEOUS. (_Papyrus_, a kind of paper made of the flags of the river

   Nile in Egypt.) Of a thin, light texture, resembling that of paper. An

   example of this is to be seen in the Argonauta, commonly called the

   "Paper Sailor," fig. 485, and in the Pholas papyracea, fig. 56.

 

   PAPYRIDEA. Sw. A sub-genus of Cardium, thus described; "Shell

   heart-shaped, or transversely oval; inequilateral; the anterior side

   almost always gaping; representing the Pholidæ. P. Soleniforme, Wood,

   Conch. pl. 56. f. 3.--apertum, Ib. 56. f. 2.--transversum, Sow. Conch.

4.--ringens, Wood, pl. 53. f. 1, 2."

 

   PARACEPHALOPHORA. Bl. The second class of the type Malacozoa, Bl.

   divided into the sub-classes: P. dioica, P. monoica, P. hermaphrodita.

 

   PARIES. (_A wall._) The principal part of a multivalve shell, forming a

   circular wall round the body of the animal, and composed of one or more

   valves which are called the parietal valves.

 

   PARIETAL VALVES. The principal valves of multivalve shells surrounding

   the body like a wall; as distinguished from the opercular valves, or

   those which compose the operculum.

 

   PARMACELLA. Cuv. (_A little cell._) _Fam._ Limacinea, Lam. and

   Bl.--_Descr._ Haliotoid, internal, thin; spire flat, consisting of one

   or two rapidly increasing whorls; aperture as large as the whole shell,

   with the dorsal margins inflected.--_Obs._ This description applies to

   Parmacella of Cuvier. The shell figured in Sowerby's Genera under that

   name is Cryptella of Webb. Fig. 257, P. Olivieri. Fig. 258, P.

   Palliolum.

 

   PARMOPHORUS. Bl. A genus composed of EMARGINULA elongata, Auct. and

   other species of a similarly elongated form. Australian. Fig. 242. P.

   elongatus.

 

   PARTULA. Fer. _Fam._ Colimacea, Lam. Auriculacea, Fer.--_Descr._

   Conical, smooth; spire equal to the aperture in length, consisting of

   few whorls; aperture auriform; outer lip reflected, broad; inner lip

   reflected, with a slight prominence on the columella. P. australis,

   fig. 302.

 

   PASITHÆA. Lea. A genus formed of some pyramidal shells, described as

   resembling Melania, but separated from that genus on account of being

   marine fossils. Fig. 317, P. striata.

 

   PATELLA. Auct. (_A dish_ or _platter_.) _Fam._ Phyllidiana, Lam.

   Retifera, Bl.--_Descr._ Symmetrical, compresso-conical, nearly regular,

   oblong or oval; apex sub-central, inclining towards the anterior

   margin; aperture oval, forming the base of the shell; internal surface

   smooth; with a muscular impression shaped like a horse-shoe, with the

   ends bending forwards, encircling and dividing the space all round,

   except where the interruption occurs to receive the head of the animal;

   external surface ribbed, grooved, striated or banded radiately. On

   rocks and sea-weeds in all climates.--_Obs._ Patelloida differs from

   Patella in the construction of the animal; Siphonaria, in the lateral

   siphon; and Ancylus, in the oblique twist of the axis, as well as in

   the nature of the animal. The Patellæ are marine. Fig. 229, P. Oculus.

 

   PATELLIFORM. (_Patella_, a dish; _forma_, shape.) Shaped like a dish,

   or like shells of the genus Patella.

 

   PATELLOIDA. Quoy and Gaimard. LOTTIA, Gray.--_Fam._ Phyllidiana,

   Lam.--_Descr._ Patelliform, rather flat; apex obtuse, leaning towards

   the posterior margin; muscular impression not symmetrical, but widest

   on the right side near the head of the animal; central disc of a

   variable brown colour. On rocks and sea-weeds in all climates.--_Obs._

   The shells of this genus so closely resemble Patella that it is almost

   impossible to make the distinction from the shells alone. They are,

   however, generally flatter, and have the apex placed somewhat nearer

   the posterior margin. The animals are very distinct. Fig. 231, P.

   Antillarum.

 

   PATELLOIDEA, Bl. or patelliform shells. The third family of the order

   Monopleurobranchiata, Bl.; the animals of which are described as

   depressed, flattened, covered by a wide external shell, which is

   patelliform and non-symmetrical. This family contains the genera

   Umbrella and Siphonaria.

 

   PATROCLES. Montf. A genus of microscopic Foraminifera.

 

   PATULARIA. Sw. A sub-genus of "Anodontinæ," Sw. thus described: "Shell

   nearly equilateral, round or cordate; no teeth. P. ovata, Sw." _Ex._

   _Conch._ pl. 36. rotundatus, Ib. pl. 137.

 

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

 

   PAXYODON. Schum. HYRIA, Lam.

 

   PECTEN. Brug. (_A comb._) _Fam._ Pectenides, Lam. Subostracea,

   Bl.--_Descr._ Inequivalve, ribbed longitudinally, nearly equilateral,

   with a triangular auricle on each side of the umbones; hinge linear,

   destitute of teeth, having a central pit containing the cartilage;

   muscular impressions one in each valve, large, sub-central.--_Obs._

   This genus of beautiful shells, to which the well known Scallop

   belongs, contains numerous species, some of which are found in the

   British Seas. The Hinnites Pusio (P. Pusio of some authors) has been

   separated on account of the irregularity of the external surface of one

   valve. Fig. 171 to 173.

 

   PECTENIDES. Lam. A family belonging to the second section of the order

   Conchifera Dimyaria, Lam. including the following genera.

 

PECTEN. Unattached, including _Decatopecten_ and _Hinnites_.

       Fig. 171, 172, 173.

 

LIMA. Unattached, gaping, Fig. 174.

 

PLAGIOSTOMA. Unattached, with an area between the umbones. Fig.

       176.

 

DIANCHORA. Attached by the point of the umbo. Fig. 175.

 

SPONDYLUS. Attached, irregular, a triangular area in one valve,

       divided by a slit. Fig. 177.

 

PLICATULA. Plicated, a very small area in one valve. Fig. 178.

 

   PECTINATED. (_Pecten_, a comb.) Marked in a regular series of ridges.

 

   PECTUNCULUS. (_Pecten_, dim.) _Fam._ Arcacea, Lam. and Bl.--_Descr._

   Equivalve, sub-equilateral, orbicular, thick, covered with a velvety

   epidermis, striated longitudinally; ventral margin denticulated within;

   hinge semi-circular, with a series of small teeth on each side of the

   umbones, which are separated by a small triangular disc in each valve

   bearing the ligament; muscular impressions two in each valve, strongly

   marked, united by an entire palleal impression.--_Obs._ Linnæan

   conchologists have mixed this genus with Arca, from which it is,

   however, totally distinct, not only in the roundness of the general

   form, but also, and principally, in the curve of the hinge line; in

   fact the characters of this genus are so strongly marked that there is

   no danger of confounding it with any other. It does not contain many

   species; two or three are British. The fossil species occur in London

   Clay and Calcaire-grossiér. Fig. 134, P. pilosus.

 

   PEDICLE or PEDUNCLE. (_Pedunculus_, a little foot.) The stem or organ

   of attachment of the class of shells called in the system of Lamarck

   "Pedunculated Cirripedes," consisting of a fleshy tendinous tube, by

   the lower end of which they are attached to sub-marine substances.

 

   PEDICULARIA. Sw. A genus of "Scutibranchia," thus described: "Shell

   irregular, sub-patelliform; a thick, large, obsolete apex on one of the

   longest sides, and an internal callous rim within, on one side only;

   circumference undulated, irregular. P. Sicula, Sw." Sw. p. 357. Sicily.

   A singular shell of the nature of Calyptræa, which is found attached to

   corals, conforming its shape to the irregularity of their surface, and

   fitting closely. _Ex._ Fig. 513.

 

   PEDIPES. Adanson. _Fam._ Auriculacea, Bl. Colimacea, Lam.--_Descr._

   Sub-globose, longitudinal, thick, striated; spire equal to the