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

aperture

   in length; aperture sub-ovate; peritreme sharp, thickened within,

   modified by the last whorl; columella with three strong plaits on the

   inner edge; outer lip with one fold.--_Obs._ This genus contains but

   one or two small recent species, which in some respects resemble

   Auricula, from which it is known by the thickness of its shell, and its

   globular form. Fig. 299, P. Adansoni. Coast of Africa.

 

   PEDUM. Lam. (_A shepherd's crook._) _Fam._ Pectinides, Lam.

   Sub-ostracea, Bl.--_Descr._ Irregular, inequivalve, sub-equilateral,

   attached by a byssus passing through a sinus in the lower valve; hinge

   toothless, with a triangular area in each valve, separating the

   umbones; ligament contained in a groove running across the area;

   muscular impressions one in each valve, large, sub-orbicular; both

   valves flat, narrow at the dorsal, broad at the ventral extremities;

   lower valve with raised edges overwrapping the upper.--_Obs._ This

   singular genus, of which only one species is known, differs from

   Ostrea, not only in shape and structure, but also in the mode of

   attachment, which is by means of a byssus passing through the lower

   valve, in Pedum, but by a portion of the outer surface of the shell in

   Ostrea. P. Spondyloideum (fig. 179) is the only species at present

   known. Moluccas.

 

   PEDUNCLE. See PEDICLE.

 

   PEDUNCULATED. (_Pedunculus_, a little foot.) Attached to external

   objects by a hollow fleshy tube, called the Peduncle.

 

   PEDUNCULATED CIRRIPEDES. Lam. An order consisting of molluscs which

   have multivalve shells, supported on a peduncle. The genera which it

   contains are thus distinguished:

 

PENTELASMIS. Five valves. Fig. 34.

 

CINERAS. Five very minute valves distant from each other. Fig.

       42.

 

OTION. The same, but the animal has two auricles. Fig. 43. The

       genus Palmina, Gray, has but one.

 

OCTOLASMIS. Shaped like Pentelasmis, but with 7 or 8 valves.

       Fig. 41.

 

LITHOTRYA. Five valves, peduncle scaly with a plate at the base.

       Fig. 39.

 

SCALPELLUM. Shape square, valves 13, peduncle scaly. Fig. 35.

 

SMILIUM. Same, but the peduncle hairy. Fig. 36.

 

IBLA. Four valves, one pair long, one pair short, peduncle

       hairy. Fig. 40.

 

BRISMEUS. Seven valves, even at the base. Fig. 38.

 

POLLICIPES. Principal valves in pairs, with many smaller valves

       at the base. This genus has been divided into _Pollicipes_, and

       _Capitellum_, the latter of which is founded upon Pollicipes

       Mitellus, Auct. Fig. 37 and 37*.

 

   PELAGUS. Montf. A genus composed of species of AMMONITES, which have

   the spire covered by the last whorl, as in Nautilus and have an

   umbilicus. ORBULITES. Bl.

 

   PELLUCID. Transparent.

 

   PELORUS. Montf. POLYSTOMELLA, Bl. A genus of microscopic Foraminifera.

 

   PELORONTA. Oken. NERITA _Peloronta_, Auct. Fig. 330.

 

   PENEROPLIS. Montf. A genus of microscopic Foraminifera.

 

   PENICILLUS. Brug. ASPERGILLUM, Auct.

 

   PENTALEPAS. Bl. PENTELASMIS, Auct.

 

   PENTAMERUS. Sow. ([Greek: Pente], _pente_, five; [Greek: meros],

   _meros_, part.) _Fam._ Brachiopoda, Lam.--_Descr._ Equilateral,

   inequivalve; one valve divided by a central septum into two parts; the

   other by two septa, into three parts; umbones incurved,

   imperforate.--_Obs._ Dalman remarks upon his genus Gypidia, that it is

   most probably identical with PENTAMERUS, Sow. but rejects the name for

   two reasons; 1st. That it has already been applied to a class of

   insects; 2nd. He disputes the fact of the shell being quinquelocular,

 i.e. not counting the triangular foramen in the hinge of the larger

   valve as one of the divisions. Fig. 212, 213.

 

   PENTELASMIS. Leach. ([Greek: pente], _pente_, five; [Greek: elasma],

   _elasma_, plate.) _Order._ Pedunculated Cirripedes, Lam.--_Descr._

   Compressed, conical, composed of five valves; lower lateral pair

   sub-trigonal; upper lateral pair elongated, sub-quadrate; dorsal valve

   arcuate, peduncle elongated, smooth. Found on floating wood in the

   sea.--_Obs._ This genus is known from all others of the order by the

   number of valves. Pentelasmis is the genus Anatifera of Lamarck. Lepas

   anatifer, Linn. Fossil species of this marine genus are found in the

   Calcaire-grossièr of Paris, and in other similar beds. Fig. 34, P.

   lævis.

 

   PENULTIMATE WHORL. The last whorl but one.

 

   PERA. Leach. A genus composed of CYCLAS amnica, and other similar

   species.

 

   PERDIX. Montf. DOLIUM _Perdix_, Auct.

 

   PERFORATED. (_Perforatus._) Bored through, as the apex of Fissurella,

   fig. 245, and Dentalium, fig. 2.

 

   PERFORATION. (_Perforo_, to bore, or pierce.) A round opening, having

   the appearance of being bored, as in Haliotis, fig. 338. Sometimes the

   term is applied to an umbilicus which penetrates a shell through the

   axis to the apex, as Eulima splendidula, fig. 348.

 

   PERIBOLUS. Brug. A genus founded upon young specimens of CYPRÆA, with

   their outer lips not formed.

 

   PERIOSTRACUM. A name used by Mr. Gray to signify the substance which

   covers the outer surface of many shells, called the _Epidermis_ by most

   conchological writers. "Drap Marin" is the name given to this substance

   by French Naturalists.

 

   PERIPLOMA. Schum. _Fam._ Myariæ. A genus thus described: "Shell very

   thin with the left valve more ventricose than the right; hinge

   toothless, ligament double, the external portion thin, the internal

   part thick, placed upon prominent, sometimes spoon-shaped hinge laminæ,

   and supported by a transverse bone; muscular impressions two, distant,

   palleal impression sinuated posteriorly." _Ex._ P. inæquivalvis. fig.

_Genus_, Osteodesma, Deshayes.

 

   PERISTOMATA. Lam. A family belonging to the first section of the order

   Trachelipoda, containing the following genera:--

 

AMPULLARIA. Globose or discoidal; operculum concentric;

       including _Pachystoma_, _Lanistes_, _Ceratodes_. Fig. 318 to 320.

 

PALUDINA. Oval; operculum concentric. Fig. 321.

 

VALVATA. Globose; operculum spiral. Fig. 322.

 

   PERISTOME. The edge of the aperture, including the inner and outer

   lips.

 

   PERITREME. A term used to express the whole circumference of the

   aperture of a spiral shell. It is said to be notched or entire, simple,

   reflected, round or oval, &c.

 

   PERLAMATER. Schum. (_Mother of Pearl._) MELEAGRINA Margaritifera, Lam.

   The pearl oyster.

 

   PERNA. Auct. ("Pernæ concharum generis," Plin.) _Fam._ Malleacea,

   Lam.--_Descr._ Sub-equivalve, irregular, compressed, foliaceous; hinge

   straight, linear, composed of a series of transverse, parallel grooves,

   containing the cartilage and intermediate spaces bearing the ligament;

   anterior margin with a sinus for the passage of a byssus; posterior

   ventral margin oblique, attenuated. _Obs._ This genus is known from

   Crenatula by the straightness, number and regularity of the grooves in

   the hinge and the sinus, for the passage of the byssus. Fig. 166, P.

   Ephippium. Mostly tropical.

 

   PERSICULA. Schum. A genus formed of MARGINELLA _Persicula_, Auct. and

   other species having the spire concealed. Fig. 438.

 

   PERSONA. Montf. (_Mask_). A genus composed of TRITON _Anus_, Auct. and

   similar species. Fig. 401.

Class CIRRIPEDES.pg. 3

 

   PETRICOLA. Lam. (_Petrus_, a stone; _cola_, an inhabitant.) _Fam._

   Lithophagidæ, Lam.--_Descr._ Equivalve, inequilateral, transversely

   ovate or oblong, rather irregular, anterior side rounded; posterior

   side more or less attenuated, slightly gaping; hinge with two cardinal

   teeth in each valve; muscular impressions two in each valve; palleal

   impression entire; ligament external.--_Obs._ The Petricolæ are found

   in holes made by the animals in rocks, madrepores, &c. They may be

   known from Saxicava by the regularity of their form and the teeth on

   the hinge. Fig. 91, 92.

 

   PETRIFIED FINGERS, CANDLES, SPECTRE CANDLES, &c. are vulgar terms by

   which fossils of the genus Belemnites were formerly known.

 

   PHAKELLOPLEURA. Guild. A genus composed of those species of CHITON,

   Auct. which have bunches of hairs or hyaline bristles on each side of

   each valve on the margin. The Chiton fascicularis, found on our own

   coasts, is a well known example. Fig. 506.

 

   PHARAMUS. Montf. LENTICULINA, Bl. A genus of microscopic Foraminifera.

 

   PHARETRIUM. König. ([Greek: pharetreôn], _pharetrion_, a

   quiver.)--_Descr._ A testaceous body composed of two conical sheaths,

   one within the other, perforated at the apex, and joined together near

   the oral margin. P. fragile, fig. 3. In describing this genus, which

   appears to be the same as ENTALIS of Defrance, Mr. König expresses the

   supposition that it may probably belong to the class Pteropoda.

 

   PHASIANELLA. Auct. (_Phasianus_, a pheasant.) _Fam._ Turbinacea, Lam.

   Ellipsostomata, Bl.--_Descr._ Smooth, oval, variegated; aperture

   entire, oval; outer-lip thin; inner-lip thin, spread over a portion of

   the body whorl; columella smooth, rather thickened towards the base;

   operculum horny, spiral within; testaceous, incrassated without.

   Britain, Mediterranean, &c.; the fine large species are Australian.

   Some fossil species are found in the tertiary beds.--_Obs._ The shells

   composing this genus are richly marked with lines and waves of various

   and delicate colours, and if the genus be restricted to those species

   which are smooth, and which have a thick shelly operculum, we may

   regard it as well defined; but there are some spirally-grooved species

   of TURBO, Linn. which, from their oval shape, have been considered as

   belonging to this genus. Such species should not, in our opinion, be

   retained in this genus; they belong to Littorina. P. variegata, fig.

   367.

 

   PHITIA. Gray. CARYCHIUM, Müller.

 

   PHOLADARIA. Lam. A family of the order Conchifera Dimyaria, Lam. The

   animals contained in this family live in cavities bored by themselves

   in rocks, wood, &c. They are cylindrical in form. Lamarck here places

   PHOLAS and GASTROCHÆNA, the last of which belongs more properly to the

   family of Tubicolaria, where we have enumerated it. Pholas has been

   divided into _Pholas_, fig. 55, _Martesia_, which has the valves nearly

   closed; and Pholadidæa, fig. 56, which has the cup-shaped extension.

   The genus Pholadomya, fig. 67, has been added, although of doubtful

   character. The genus Galeomma, fig. 58, 59, has also been recently

   added.

 

   PHOLADIDÆA. Leach. PHOLAS papyracea, Auct. Remarkable for the

   cup-shaped process at the posterior extremity. Fig. 56.

 

   PHOLADOMYA. Sow. (_Pholas_ and _Mya_.) _Fam._ Pholadaria,

   Lam.--_Descr._ Thin, rather hyaline, equivalve, inequilateral,

   ventricose, posteriorly gaping, elongated, anteriorly short, rounding;

   ventral margin rather gaping; hinge with an elongated pit, and lateral

   plate in each valve; ligament external, short, muscular impressions two

   in each valve, rather indistinct; palleal impression with a large

   sinus.--_Obs._ The only recent species of this genus is from the island

   of Tortola. Several fossil species occur in rocks of the Oolitic

   series. Fig. 57, P. candida.

 

   PHOLAS. Auct. ([Greek: PHôleô], _pholeo_, to lie hid in a cavity.)

   _Fam._ Pholadaria, Lam. ADESMACEA, Bl.--_Descr._ Transverse, oblong,

   equivalve, inequilateral, imbricated, gaping on both sides, the

   anterior hiatus being generally the largest, although sometimes nearly

   closed, with the dorsal margin surmounted with one or more laminar

   accessary valves; hinge callous, reflected, with a long curved tooth

   protruding from beneath the umbones in each valve.--_Obs._ This genus

   of marine shells, dwelling in holes formed in rocks, wood, &c. is

   easily distinguished from any other nearly allied genus by the curved,

   prominent, rib-like teeth. Fig. 55, P. Dactylus; 56. P. papyracea.

 

   PHOLEOBIUS. Leach. Part of the genus SAXICAVA, Auct.

 

   PHONEMUS. Montf. A genus of microscopic Foraminifera.

 

   PHORUS. Montf. TROCHUS agglutinans, Auct. Remarkable for the adhesion

   of little pebbles, dead shells, &c. to the outer edge of the whorls,

   which are taken up in the course of the growth of the shell. From this

   circumstance they are called "Collectors, Carriers, &c." Fig. 360.

   Recent species are brought from the East and West Indies; fossil

   species are found in the Tertiary beds.

 

   PHOS. Montf. _Fam._ Purpurifera? Lam.--_Descr._ Turrited, thick,

   cancellated, varicose; spire pointed, generally longer than the

   aperture; aperture rounded or oval; outer lip having internal ridges,

   with a sinus near the anterior termination; columella with an oblique

   fold; canal short, forming externally a raised varix.--_Obs._ The

   raised external surface of the canal, brings this genus near to

   Buccinum, while, in general appearance, most of the species more nearly

   resemble Murex. They have, however, no true varices on the whorls, but

   merely raised bars. Fig. 416, P. senticosus.

 

   PHYLLIDIANA. Lam. A family belonging to the first section of the order

   Gasteropoda, Lam. The genera belonging to this family may be