Lam. and Bl.--_Descr._ Irregular, inequivalve, generally inequilateral,
foliaceous, attached by part of the lower valve; hinge sometimes
slightly crenated; destitute of teeth; with the ligament spread upon
the lower part of a central, triangular area, which is divided into
three parts; upper valve much flatter than the lower; muscular
impressions one in each valve, large, sub-central, sub-orbicular, with
one very minute.--_Obs._ The Linnæan Genus Ostrea includes the Pectens
and many other genera so different from each other that, without any
desire to increase the number of genera, it was found necessary by
subsequent authors to separate them. The common Oyster is the type of
this genus as at present constituted, and is well known to be abundant
in various parts of the world. Those which depart furthest from this
type are the Gryphæa, Lam. with a prominent, incurved umbo in the lower
valve. The Dendostrea, Sw. with margins characterized by strongly
angulated folds, throws out arms from the lower valve, by which they
are attached to stems of sea-weed, &c. Fig. 180, O. edulis. Fig. 181,
O. folium. (Dendostrea, Sw.) Fig. 182, Gryphæa incurva. Fig. 183,
Exogyra conica.
OTIDES. Bl. The first order of Scutibranchiata, Bl. containing the
genera Haliotis and Ancylus.
OTION. Leach. ([Greek: ôtion], a little ear.) _Order._ Pedunculated
Cirripedes, Lam.--_Descr._ Body sub-quadrate, supported on a fleshy
pedicle with a gaping aperture and two posterior auricular tubes;
valves five, separate, two semilunar, placed at the sides of the
aperture, two terminal, very small, one dorsal, minute.--_Obs._ Otion
differs from Cineras in having two cylindrical posterior tubes, and in
the extreme minuteness of three out of five of the valves. Found on
spars floating in the sea, &c. O. Cuvierii, (Lepas aurita, Linn.) Fig.
43, O. Cuvieri.
OTIS. Humph. AURICULA, Lam.
OVATE. (_Ovatus._) Egg-shaped or oval.
OVEOLITHES. Montf. A microscopic shell resembling Bulla.
OVIPAROUS MOLLUSCA. Those which produce their young in eggs. Used in
distinction from the VIVIPAROUS MOLLUSCA, whose young are perfectly
formed before they leave the body of the parent.
OUTER LIP. See LABRUM.
OVULUM. Brug. (_Ovum_, an egg, dim.) _Fam._ Convoluta, Lam.
Angyostomata, Bl.--_Descr._ Ovate or fusiform, smooth, convolute, spire
covered; aperture narrow, with a canal at each extremity; outer lip
crenulated, inflected; inner lip smooth, callous towards the spiral
extremity; dorsal area wide, sometimes indistinctly marked.--_Obs._ The
Ovula were placed by Linnæus in his genus Bulla, from which they are
very remote. They differ from Cypræa in having the inner lip 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.
6. 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.
90. 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.
f. 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.
1. PECTEN. Unattached, including _Decatopecten_ and _Hinnites_.
Fig. 171, 172, 173.
2. LIMA. Unattached, gaping, Fig. 174.
3. PLAGIOSTOMA. Unattached, with an area between the umbones. Fig.
176.
4. DIANCHORA. Attached by the point of the umbo. Fig. 175.
5. SPONDYLUS. Attached, irregular, a triangular area in one valve,
divided by a slit. Fig. 177.
6. 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 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:
1. PENTELASMIS. Five valves. Fig. 34.
2. CINERAS. Five very minute valves distant from each other. Fig.
42.
3. OTION. The same, but the animal has two auricles. Fig. 43. The
genus Palmina, Gray, has but one.
4. OCTOLASMIS. Shaped like Pentelasmis, but with 7 or 8 valves.
Fig. 41.
5. LITHOTRYA. Five valves, peduncle scaly with a plate at the base.
Fig. 39.
6. SCALPELLUM. Shape square, valves 13, peduncle scaly. Fig. 35.
7. SMILIUM. Same, but the peduncle hairy. Fig. 36.
8. IBLA. Four valves, one pair long, one pair short, peduncle
hairy. Fig. 40.
9. BRISMEUS. Seven valves, even at the base. Fig. 38.
10. 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.
72. _Genus_, Osteodesma, Deshayes.
PERISTOMATA. Lam. A family belonging to the first section of the order
Trachelipoda, containing the following genera:--
1. AMPULLARIA. Globose or discoidal; operculum concentric;
including _Pachystoma_, _Lanistes_, _Ceratodes_. Fig. 318 to 320.
2. PALUDINA. Oval; operculum concentric. Fig. 321.
3. 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.
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.