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
distinguished as follows:
1. CHITON. Composed of eight valves; valves contingent. Fig. 227.
2. CHITONELLUS. The same, with the valves distant. Fig. 228.
3. PATELLA. Conical, symmetrical. Fig. 229, 230.
4. PATELLOIDA. Differing from Patella in the animal. Fig. 231.
5. SIPHONARIA. With a siphon on one side. Fig. 231*.
6. SCUTELLA. Siphon close to the side of the head. Fig. 510, 511.
PHYLLONOTUS. Sw. A sub-genus of Murex, thus described: "Canal moderate;
varices foliated, laciniated, compressed, or resembling leaves;
inflatus. Mart. 102. fig. 980, eurystoma. Zool. Ill. ii. 100.
imperialis. Ib. pl. 109." Sw. p. 296.
PHYSA. Drap. A genus formed for reversed species of Limnæa, Auct. Fig.
310, P. castanea.
PHYSETER. Humph. SOLARIUM, Lam.
PILEOLUS. Cookson. (_A little cap._) _Fam._ Neritacea, Lam.--_Descr._
Patelliform, with the apex sub-central, straight. In the lower disc, or
under surface, the centre of which is rather raised or cushion-shaped,
is placed the lateral, narrow, semilunar aperture, with the outer lip
marginated and the inner lip crenulated.--_Obs._ This interesting genus
is known only in a fossil state. Two species are found in the upper
layer of Oolite, above the Bradford clay. The spire, although internal,
connects this genus in some degree with Neritina. Still there is no
danger of confounding them. Fig. 332, P. plicatus.
PILEOPSIS. Lam. CAPULUS, Montf.
PILLAR. The usual English name for the column which forms the axis of
spiral shells, around which the whorls revolve. See COLUMELLA.
PINNA. Auct. (_The fin of a fish._) _Fam._ Mytilacea, Lam.--_Descr._
Equivalve, inequilateral, oblique, wedge-shaped, thin, horny; umbones
terminal; hinge rectilinear, without teeth; anterior margin sinuated,
to admit the passage of a byssus; posterior margin truncated, gaping;
muscular impressions two in each valve; posterior large, sub-central;
anterior small, terminal, sometimes double.--_Obs._ The beautiful large
shells of which this genus is composed, are possessed of a large,
flowing, silky byssus, of which gloves and hose have been manufactured.
They have received their name from their resemblance to the pectoral
fins of some fishes. Some species attain very large dimensions, and
measure two feet in length. A very improbable story is told with regard
to animals of this genus, namely that a certain small species of crab
is in the habit of taking refuge from its enemies in the shell of the
Pinna, into which it is received with great hospitality and kindness by
the "_blind slug_," which inhabits it. In return for which kindness, he
occasionally goes abroad to procure food for both. On his return he
knocks at the shell, which is opened to receive him, and they share the
supplies together in convivial security! Some species are smooth,
although the greater number are imbricated or crisped outside. P.
saccata, fig. 162.
PINNATED. (From _Pinna_, a fin.) When a part of a shell is spread out
and smooth, as in Rostellaria columbaria, fig. 403, it is said to be
_alated_, or winged, but when the part which is spread is radiated or
ribbed, like the fin of a fish, it is _pinnated_, as in Murex pinnatus,
and Murex tripterus. (Conch. Illustr.)
PIRENA. Lam. A genus of fresh-water shells, rejected by De Ferussac and
other authors, who place Lamarck's two first species with Melanopsis,
and his two last with Melania. Fig. 316, P. terebralis.
PISIDIUM. Leach. A genus of river shells separated from Cyclas
principally on account of a difference in the animal. The species of
Pisidium, however, are less equilateral than the Cyclades, and the
posterior or ligamentary side of the latter is the longer, while that
of the former is the shorter. Fig. 112.
PISIFORM. (_Pisum_, a pea; _forma_, shape.) Shaped like a pea or small
globular body.
PISUM. Megerle. (_A pea._) PISIDIUM, Leach.
PITHOHELIX. Sw. A sub-genus of "Geotrochus," Sw. Sw. p. 332.
PITONELLUS. Montf. ROTELLA, Auct.
PLACENTA. Schum. PLACUNA, Auct.
PLACENTULA. Schum. A genus of microscopic Foraminifera.
PLACUNA. Brug. ([Greek: plakous], _placos_, a cake.) _Fam._ Ostracea,
Lam. and Bl.--_Descr._ Compressed, thin, equivalve, nearly equilateral,
planorbicular, fibrous, foliaceous; hinge flat, with two diverging ribs
in one valve, and two corresponding grooves in the other, containing
the cartilage; muscular impressions one, large, circular, central, and
one or two smaller in each valve.--_Obs._ The two best known species of
this well defined genus are the P. Placenta, commonly called the
Chinese Window Shell, and the P. Sella, called the Saddle Oyster, from
the anterior margin being turned up so as to resemble a saddle. The
genus may be known from all others by the diverging costa on the hinge.
Placunanomia is the only genus resembling it in this respect, but this
is easily distinguished by a perforation through the shell. Fig. 184,
P. Placuna. These shells are used in China to glaze windows.
PLACUNANOMIA. (Sw. _Placuna_ and _Anomia_.) _Fam._ Ostracea, Lam. and
Bl.--_Descr._ Thin, foliaceous, compressed, sub-equivalve,
sub-equilateral, irregular, flat near the umbones, plicated towards the
margins, attached by a bony substance passing through a fissure in the
lower valve; hinge flat, with two diverging ribs in one valve,
corresponding with two diverging grooves, containing the cartilage, in
the other; muscular impressions one in each valve, central,
sub-orbicular.--_Obs._ The specimens from which Mr. Broderip described
this singular genus, were brought by Mr. Cuming from the gulf of Dulce
in Costa Rico. Another species is from one of the Philippine Islands.
They partake of the characters of several genera, having the hinge of
Placuna, and being attached by a process passing through the lower
valve, like Anomia. P. Cumingii, fig. 189.
PLAGIOSTOMA. Sow. Min. Con. ([Greek: plagios], _plagios_, oblique;
[Greek: stoma], _stoma_, mouth.) _Fam._ Pectenides, Lam.
Palliobranchiata, Bl.--_Descr._ Sub-equivalve, inequilateral, oblique,
auriculated on each side of the umbones, radiately striated; hinge
straight in one valve, with a triangular notch in the other.--_Obs._
This genus, one species of which is spinous, and another smooth, is
only known in a fossil state. It is found in the Lias and chalk. Fig.
176, P. spinosum.
PLAIT or FOLD. A term applied to the prominences on the columellar lip
of some univalve shells, particularly in the sub-family of Volutidæ.
_Ex._ Voluta, fig. 433; Cymba, 434; and Melo, fig. 435.
PLANARIA. Brown. A minute fossil resembling Planorbis in appearance,
but differing in being a marine shell, and having a reflected outer
lip. P. nitens, fig. 312, from Lea's Contributions to Geology.
PLANAXIS. Lam. (_Plana_, flat; and _axis_.) _Fam._ Turbinacea, Lam.
Entomostomata, Bl.--_Descr._ Sub-ovate, pyramidal, solid; spire
measuring ½ or 1/3 of the axis, consisting of few whorls; columella
contiguous to the axis, flat, truncated, and separated from the outer
lip by a short canal; outer lip thickened and denticulated within;
operculum horny, thin, with a terminal nucleus.--_Obs._ This is a genus
of small marine shells found in the West Indies, &c. Fig. 365, P.
sulcata.
PLANE. (_Planus._) Flat, planed, as the columellar lip of Purpura, fig.
414.
PLANORBICULAR, (_Planus_, flat; _orbis_, an orb.) Flat and circular, as
Ammonites, fig. 478.
PLANORBIS. Müll. (_Planus_, flat; _orbis_, an orb.) _Fam._ Lymnacea,
Lam. and Bl.--_Descr._ Thin, horny, convolute, planorbicular, nearly
symmetrical; spire compressed, concave, consisting of numerous
gradually increasing whorls, which are visible on both sides; aperture
transversely oval, or nearly round; peritreme entire; outer lip thin;
inner lip distinct, spread over a part of the body whorl.--_Obs._ This
is a genus of shells abounding in all climates in ditches and stagnant
pools, not liable to be confounded with any other, excepting the
discoidal species of Ampullaria, which may be distinguished by the
aperture being broadest in the opposite direction. It is further to be
remarked that the discoidal Ampullariæ are dextral shells, and the
Planorbes are sinistral or reversed; and although the latter are
sometimes so flat and orbicular that it is difficult to know which is
the spiral side, it may nevertheless always be ascertained by a careful
examination. Fossil species are found in the freshwater strata of the
Isle of Wight, and the neighbourhood of Paris. Fig. 311, P. corneus.
PLANORBULINA. D'Orb. A genus of microscopic Foraminifera.
PLANULACEA. Bl. The second family of Cellulacea, Bl. The microscopic
Foraminifera contained in this family are described as very much
depressed, not spiral, chambered, cellular, and having the septa
indicated by grooves on the external surface of the shell, which
increase in length from the apex to the base: some of the small
cellular cavities are to be seen on the margins. This family contains
the genera Renulina and Peneroplis.
PLANULARIA. Defr. PENEROPLIS, Montf. A genus of microscopic
Foraminifera.
PLANULINA. D'Orb. A genus of microscopic Foraminifera.
PLANULITES. Lam. DISCORBITES of the same author. A genus of microscopic
Foraminifera.
PLATIRIS. Lea. ([Greek: platus], _platus_, wide; [Greek: iris],
_iris_.) A genus including several species of Nayades, referred to
IRIDINA, Lam. The genus Platiris is divided into two sub-genera.
Iridina, species which have crenulated margins; I. Ovata, I. exotica,
Spatha, Lea; those with smooth or very slightly crenulated hinges, S.
rubeus, S. Solenoides, Mycetopus, D'Orb. Fig. 151.
PLATYLEPAS. ([Greek: platus], _platus_, wide; [Greek: lepas], _lepas_,
rock.) _Order._ Sessile Cirripedes, Lam. _Fam._ Balanidea,
Bl.--_Descr._ Conical, depressed, consisting of six valves, each
divided internally by an angular plate jutting from the centre (like
the buttress of a wall); operculum consisting of four valves in
pairs.--_Obs._ This genus differs from Balanus, Coronula, &c. in the
internal structure of the valves. De Blainville's description of
Chthalamus partly agrees with this. Fig. 19.
PLECTOPHORUS. Fer. ([Greek: plêktron], _plectron_, spur; [Greek:
phoreô], _phoreo_, to carry.) A genus consisting of small testaceous
appendages fixed on the posterior extremity of a species of slug. P.
corninus, fig. 260.
PLEIODON. Conrad. IRIDINA, Lam. _Fam._ Nayades, Lam.
PLEKOCHEILUS. Guild. AURICULA Caprella, Lam. CARYCHIUM undulatum,
Leach. (CAPRELLA, Nonnull.) This proposed genus is described as
scarcely umbilical, dextral, oval, spiral; with the spire elevated,
obtuse; the two last whorls very large, ventricose; aperture entire,
elongated; columella with a single plait; the plait concave, inflected.
Fig. 522, 523.
PLEUROBRANCHUS. Cuv. ([Greek: Pleura], _pleura_, the side; _Branchiæ_,
gills.) _Fam._ Semiphyllidiana, Lam. Subaplysiacea, Bl.--_Descr._
Internal, thin, haliotoid, slightly convex towards the spiral apex;
aperture entire.--_Obs._ This is a very light shell, delicately
coloured, resembling Aplysia, but differing in the integrity of the
margin. Fig. 232, P. membranaceus.
PLEUROCERUS. Rafinesque. A genus very imperfectly described in the
"Journal de Physique" as "oval, or pyramidal; aperture oblong; outer
lip thin; inner lip truncated at the columella, which is smooth and
tortuous, not umbilicated. Operculum horny or membranaceous." De
Blainville, in giving this description, remarks that he has neither
seen the animal nor the shell of this genus, which he imagines to have
been formed from the "Paludine Coupée de M. Say."
PLEURORYNCHUS. Phillips. ([Greek: Pleura], _pleura_, the side; [Greek:
runchos], _rynchus_, a beak.) A genus founded upon a very singular
species of CARDIUM, distinguished by the short anterior side, and the
elongation of the hinge line into auricular processes, which are
truncated at the extremities. C. Hibernicum from the Black Rock near
Dublin, which is vulgarly called Asses-hoof, and C. elongatum (Sow.
Min. Con. vol. I. 82.), form part of this genus.
PLEUROTOMA. Lam. _Fam._ Canalifera, Lam. Siphonostomata, Bl.--_Descr._
Fusiform, thick, in general ribbed or striated transversely; aperture
oval, terminating anteriorly in an elongated canal; outer lip thin,
with a fissure near its spiral extremity; columella smooth, nearly
straight. Found principally in tropical climates.--_Obs._ This genus,
which nearly resembles Fusus in other respects, may be known by the
notch in the outer lip. The species differ in the length of the canal.
Swainson has designated this genus a family, thus divided into genera:
Brachytoma, in the description of which he says that the spire and
aperture are of equal length, including the species strombiformis:
Pleurotoma, in which the channel is so much lengthened, as to be little
shorter than the spire: Clavatula, having the long narrow slit of
Pleurotoma, but with a very short canal: Clavicantha, having the canal
equally short, but the sinus or notch, instead of being linear and
long, is short and wide; the surface is rough, and the whorls either
coronated with prickles, or with compressed nodules resembling spines:
Tomella, which has the spire and canal fusiform, but the spire of very
few whorls, and the inner lip considerably thickened within where it
joins the outer lip. Fig. 379, 389, P. marmorata; 381, P.
Strombiformis, (Clavatula, Sw.)
PLEUROTOMARIA. Defr. _Fam._ Turbinacea, Lam.--_Descr._ Turbinated,
spiral; aperture sub-quadrate, with rounded angles; outer lip with a
deep slit near its union with the spire.--_Obs._ This genus, which is
only known in a fossil state, abounds in inferior Oolite, Oxford clay,
and casts are found in a limestone bed in Norway. The Scissurellæ
differ in being very minute shells, and are not so trochiform as the
species of Pleurotomaria, P. reticulata, fig. 341.
PLICACEA. Lam. A family of the order Trachelipoda, Lam. containing the
following genera:
1. PYRAMIDELLA. Pyramidal, with numerous whorls. Fig. 342.
2. TORNATELLA. Cylindrical, with few whorls. Fig. 343, 344.
3. RINGICULA. Margin reflected. Fig. 540, 541.
PLICADOMUS. Sw. A sub-genus of Pupa, thus described: "spire moderate,
regular and thick, but gradually conic; the tip obtuse; aperture
perpendicular; inner lip wanting; outer lip semicircular; the margin
dilated and reflected. P. sulcata, Chem. 135, f. 1231, 1232." Sw. p.
332.
PLICATED. (_Plicatus_, folded.) Applied to spiral plaits on the
columella of some shells. _Ex._ Voluta, fig. 433. Also to the angular
bendings in the margins of some bivalve shells. _Ex._ Dendostrea, fig.
181.
PLICATULA. Lam. (_Plicatus_, folded.) _Fam._ Pectenides, Lam.
Sub-ostracea, Bl.--_Descr._ Irregular, sub-equivalve, sub-equilateral,
attached by a small part of the surface of one valve, strongly
plicated; umbones separated by a small, external ligamentary area;
hinge with two cardinal teeth in each valve, two approximate in one
valve, received between two distant in the other; cartilage placed
between the cardinal teeth; muscular impressions one in each
valve.--_Obs._ The cardinal teeth resembling those of Spondylus,
distinguish this genus from others of the Lamarckian family Pectenides.
Very few species are yet known, they are brought from the East and West
Indies and the Philippine Islands. Fossil species are found in several
of the supra-cretaceous beds. Fig. 178, P. gibbosa.
PNEUMOBRANCHIA. Lam. The second section of the order Gasteropoda, Lam.
containing the family Limacinea, fig. 256 to 263.
PODOPSIS. Lam. This genus appears to have been described from specimens
of a species of Spondylus, with the triangular disc broken out, so as
to present a similarly shaped foramen, which was supposed to afford a
passage for a large byssus.
POLINICES. Montf. A genus composed of NATICA Mammilla, and other
similar species, with mammillated spires, and the umbilicus filled with
enamel. Fig. 327.
POLLIA. Gray. TRITONIDEA, Sw. The name given by Gray was pre-occupied
by a genus of Lepidopterous Insects.
POLLICIPES. Leach. (_Pollex_, a thumb's breadth; _pes_, a foot.)
_Order._ Pedunculated Cirripedes, Lam.--_Descr._ Conical, compressed,
consisting of numerous valves, mostly in pairs, three or four pairs
forming the principal part of the shell, and surrounded at the base by
two or three rows of smaller valves, supported on a scaly, short
pedicle.--_Obs._ This description will be found to exclude Scalpellum,
and Smilium, the valves of which are more equal. The P. Mitellus, Auct.
(fig. 37*), has been separated as a genus under the name of Mitellus by
some authors, and it is certainly very different from P. polymerus,
fig. 37, and P. cornucopia.
POLLONTES. Montf. MILIOLA, Bl. A genus of microscopic Foraminifera.
POLYBRANCHIATA. Bl. ([Greek: Polus], _polus_, many; _branchiæ_, gills.)
The fifth family of the order Lamellibranchiata, Bl. containing the
genera Arca, Pectunculus and Nucula, which have a series of small teeth
on the hinge.
POLYDONTES. Montf. ([Greek: Polus], _polus_, many; [Greek: odos],
_odos_, tooth.) A species of Helix, shaped like CAROCOLLA, and having a
number of teeth in the aperture.
POLYGONAL. Many-sided.
POLYGONUM. Schum. ([Greek: Polus], _polus_, many; [Greek: gônia],
_gonia_, an angle.) A genus composed of species of TURBINELLA, Auct.
which have large continuous costæ, so as to present the appearance of
many-sided shells. T. polygonus, fig. 383. This generic name may be
used to include all those species of Turbinella, Auct. which have very
small folds on the columella.
POLYGYRA. Say. A genus of Heliciform shells, characterized by the large
number of close set whorls, constituting the spire. _Ex._ P.
Septemvolvus, fig. 275, 276.
POLYLEPAS. Bl. ([Greek: Polus], _polus_, many; [Greek: lepas], _lepas_,
rock.) SCALPELLUM, Auct.
POLYMORPHINA. D'Orb. A genus of microscopic Foraminifera.
POLYPHEMUS. Montf. A genus composed of species of ACHATINA, Auct. which
have elongated apertures, short spires, and an undulation in the outer
lip. P. Glans, fig. 288.
POLYPLAXIPHORA. Bl. The second class of the sub-type Malentozoa, Bl.
containing the genus Chiton.
POLYSTOMELLA. Lam. A genus of microscopic Foraminifera.
POLYTHALAMACEA. Bl. ([Greek: Polus], _polus_, many; [Greek: THalamos],
_thalamos_, chambers.) The third order of Cephalophora, Bl. the shells
of which are described as straight, more or less symmetrically
convolute, divided into several chambers. The septa are sometimes, but
not always, pierced by one or more siphons. This order is divided into
the families, Orthocerata, Lituacea, Cristacea, Ammonacea, Nautilacea,
Turbinacea, Turriculacea, all of which contain genera of chambered
shells. De Blainville arranges these families according to the degree
in which the spires revolve. The first being straight, as the
Orthocerata, and the last being so closely coiled up, that the last
whorl covers the rest, as in the Nautilacea.
POLYTHALAMIA. Lam. The first division of the order Cephalopoda, Lam.
containing the following families of chambered shells, viz.
Orthocerata, Lituacea, Cristacea, Sphærulacea, Radiolata, Nautilacea,
Ammonacea. Fig. 463 to 484.