Sub-quadrate, nearly equivalve, sub-equilateral, deep; hinge
rectilinear, with a series of angular teeth, small near the umbones,
larger and more oblique towards the extremities; umbones separated by a
flat external area, on which the ligament is spread. Anterior muscular
impression produced into a sharp-edged plate or ledge, projecting from
the side of the shell. Posterior muscular impression flat and
indistinct.--_Obs._ This genus very much resembles Arca in general
form, but differs in the oblique, lengthened character of the remote
teeth, and in the singularly prominent edge of the muscular impression.
China. Fig. 133, C. Auriculifera.
CUCUMIS. Klein. MARGINELLA, Auct.
CULTELLUS. Species of LUTRARIA, Lam. which have the umbones placed near
the extremity of the shell. _Ex._ L. Solenoides, fig. 78.
CUMA. Humph. FUSUS and FASCIOLARIA, Lam.
CUMINGIA. Sow. _Fam._ Mactracea, Lam.--_Descr._ Equivalve,
inequilateral, transverse, rounded anteriorly, subrostrated
posteriorly. Hinge with a central spoon-shaped cavity in each valve,
containing the cartilage; a very small anterior cardinal tooth in each
valve; two lateral teeth in one valve, none in the other: muscular
impressions two in each valve, distant; palleal impression with a very
large posterior sinus.--_Obs._ The species known at present are found
in sand, in the fissures of rocks in Tropical climates. They resemble
Erycina in general form and character, but differ in having the
internal cartilage placed in a prominent spoon-shaped process, while
that of Erycina is contained in a hollow which sinks under the umbones.
This genus should be placed near Amphidesma. Cumingia mutica, fig. 87.
CUNEIFORM. (_Cuneus_, a wedge.) Wedge-shaped, as Donax, fig. 108.
CUNEUS. Megerle. VENUS Meroe, Linn. and similar species.
CUNICULA. Sw. A sub-genus of Uniones, thus described:--"Ovate, oblong;
bosses thick, but depressed; cardinal teeth moderate. C. planulata,
patula, rubiginosa, secura, purpurascens."
CURVED. Arched or bent. _Ex._ Dentalium, fig. 2.
CURVULA. Rafinesque. A fossil imperfectly described as differing from
Pinna, in being inequivalve.
CUVIERIA. Ranz. (Baron Cuvier.) _Class_, Pteropoda, Lam.--_Descr._
Thin, transparent, glassy, cylindrical, rounded and inflated at the
closed extremity, compressed towards the opening, so as to render it
oval. This genus differs from Vaginula in being rounded, instead of
pointed, at the lower extremity. Mediterranean. Fig. 223, C. Columella.
CYCLAS. Brug. _Fam._ Conques Fluviatiles, Lam. Conchacea, Bl.--_Descr._
Orbicular, thin, subovate, ventricose, sub-equilateral, equivalve;
cardinal teeth minute, one more or less complicated in the left valve,
two diverging in the right; lateral teeth elongated, compressed,
laminar, acute, doubled in the left valve; ligament external; epidermis
thin, horny.--_Obs._ The Cyclades are viviparous, and abound in
ditches, ponds, slow streams, &c. in Europe and North America. The
genus Pisidium has been separated on account of a difference in the
animal, and may be known from Cyclas by being less equilateral, and the
anterior side being the longest. Fig. 111, C. Rivicola.
CYCLOBRANCHIATA. Bl. The third order of the second section of
Paracephalophora Monoica, Bl. containing no genera of Testaceous
Mollusca.
CYCLOCANTHA. Sw. A genus of "Trochidæ," consisting of Turbo stellaris
and T. Calcar, and corresponding with the genus Calcar, Montf.
CYCLONASSA. Sw. A genus of "Nassinæ," Sw. consisting of Nassa
Neritoidea, and corresponding with the genus Cyclops, Montf.
CYCLOPHORUS. Montf. A generic name proposed for those species of
Cyclostoma, Auct. which have an umbilicus. C. Involvulus, fig. 304,
would be the type of this genus.
CYCLOPS. Montf. NASSA Neritoidea, Auct. fig. 424.
CYCLOSTOMA. Auct. ([Greek: kuklos], _cyclos_, round; [Greek: stoma],
_stoma_, mouth.) _Fam._ Colimacea, Lam. Cricostomata, Bl. A genus of
land shells varying in shape from that of Pupa to that of a flat orb;
the aperture is generally circular and the peritreme uninterrupted,
thickened and sometimes reflected, the operculum is shelly and spiral.
Two other genera of land shells are provided with opercula, and
consequently might be confounded with this genus. In Helicina, the
operculum is concentric and the peritreme is not continuous; while in
the small genus hitherto almost unknown of Pupina, the peritreme is not
continuous and there is a glassy enamel over the whole of the external
surface. In the plates we have represented, C. ferrugineum, fig. 303;
C. involvulus, fig. 304.
CYCLOTUS. Guild. A sub-genus of Cyclostoma, consisting of those species
which are discoidal, as C. Planorbulum. Fig. 530.
CYLINDER. Montf. CONUS textile, Auct. (fig. 461) and other species
having a cylindrical form.
CYLINDRELLA. Sw. A genus of the family "Ovulinæ," Sw. composed of
cylindrical species of Ovulum? The wood-cut illustrating this genus has
the appearance of a Bulla.
CYLINDRICAL. ([Greek: kulindros], a cylinder.) This like other
mathematical terms is used with great latitude by Conchologists, and
applied to any shell the sides of which are nearly parallel, with the
extremities either rounded, flat, or conical. _Ex._ Oliva, fig. 457.
CYLLENE. Gray. _Fam._ Purpurifera, Lam.--_Descr._ Oval, thick, with a
short acute spire; an oval aperture terminating anteriorly in a slight
emargination, posteriorly in a short canal; a fold at the lower end of
the body whorl; outer lip thick, striated within; angle of the whorls
tuberculated.--_Obs._ This genus of small marine shells resembles
Voluta in general character, but differs in having a smooth columella
without folds. Recent, Pacific Ocean; Fosil, London clay. Fig. 425.
CYMBA. Brod. (_Cymba_, a boat or skiff.) _Fam._ Columellaria,
Lam.--_Descr._ Smooth, ventricose, with a very short, mammillated, rude
spire; and a very large, wide aperture, terminated anteriorly in a deep
emargination; posteriorly in a flat ledge, which separates the outer
lip from the body whorl; columella with three or four oblique, laminar,
projecting folds, terminating in a point; outer lip thin, with its edge
sharp; epidermis smooth, brown, covered partly or entirely by the
glassy enamel, which, commencing with the outer lip, spreads over the
body of the shell.--_Obs._ These very elegant shells, found in Africa,
are distinguished from the true Volutes by the shapeless, mammillated
apex of the short spire, by the large size of the aperture, and by the
horizontal ledge which separates the outer lip from the body whorl. The
genus Melo, also separated by Mr. Broderip from the Volutes, agrees
with Cymba in some respects, but differs in the regularity of the
spire. Fig. 434, C. Porcina.
CYMBIOLA. Sw. The generic name for a group of Volutes, described as
"armed with spinous tubercules, sometimes smooth, but never ribbed;
spiral whorls gradually diminishing in size, but not distorted; apex
thick and obtuse; pillar with four plaits." Mr. Swainson remarks that
this genus is chiefly distinguished by the obtuse, but not irregular
spire. The typical species are stated to be V. Rutila and V.
Vespertilio, fig. 433. Tropical.
CYMBULIA. (Dim. from _Cymba_.) _Fam._ Pteropoda, Lam. An extremely
light, cartilaginous covering of a molluscous animal, so named from its
similarity in shape to a boat. We mention it here on account of its
similarity to the shelly or glassy covering of other Pteropods, to
which, although membranaceous, it is evidently analogous. The Cymbuliæ
are found in the Mediterranean.
CYPRÆA. Auct. _Fam._ Enroulées, Lam. Angyostomata, Bl.--_Descr._ Oval
or oblong, ventricose, convolute, covered by an enamel, generally
smooth and shining. Spire short, nearly hid. Aperture long, narrow,
terminating in a short canal at both extremities. Outer lip dentated,
thickened, inflected. Inner lip dentated, thickened, reflected over
part of the body whorl.--_Obs._ These shells are so distinguished by
the two rows of teeth arranged on each side of the aperture; the
thickened front formed by the inner and outer lips; and the enamel
deposited over the back of the shell from the mantle of the animal
which envelopes it, that there is no danger of confounding them with
any other genus, except in a young state. Before they have arrived at
the full growth, the front is not thickened, and the outer lip is thin,
not inflected, nor are the teeth formed. In this state the shell
resembles, in some degree, an Oliva. Some species are striated, ribbed,
or tuberculated, but the generality are smooth. Most species belong to
tropical climates, only one to Great Britain. The C. Moneta is current
as money in some parts of Africa, and many species are worn as
ornaments by the South Sea Islanders. The colouring in most species is
exceedingly rich, and arranged in every variety of spots, patches,
rings, lines, bands and clouds. The species most esteemed by collectors
are C. Mappa, C. Testudinaria, C. Pustulata, C. Aurora, C. Princeps, of
which only two specimens are known, C. Leucodon, &c. See also
Cypræovulum, Trivea and Luponia. The fossil species are principally
from the Calc-grossier, the London Clay, Crag, &c. Fig. 445 to 450. The
latest revision of this genus has been effected by Mr. G. B. Sowerby,
sen., who has published a complete catalogue in his son's Conchological
Illustrations. This catalogue enumerates 130 species, the whole of
which are figured in parts 1 to 8, 101 to 131 of the above mentioned
work.
CYPRÆCASSIS. Stutch. (Cypræa and Cassis.)--_Descr._ Shell, when young,
striated, reticulated, or tuberculated; outer lip simple: when mature,
outer lip involute and toothed; columellar lip also toothed; aperture
straight, anteriorly terminated by a recurved canal, posteriorly by a
shallow channel. Animal with the mantle bilobed; operculum
none.--_Obs._ The reasons given for separating this genus from Cassis,
are, 1st, That the shells of the latter have an operculum, while those
of the proposed genus have none. 2nd, That the Cypræcassides do not
form a complete, thickened lip, before the full period of their growth,
like the Cassides. 3rd, That the Cypræcassides have no epidermis. The
species mentioned as probably belonging to Cypræcassis are C. rufa, the
type; C. coarctata, and C. Testiculus, Auct. The establishment of this
genus has been opposed on the ground that indications of epidermis are
discoverable in some specimens of C. rufa; that some specimens of the
same species and Testiculus have been examined, and found to have
formed slightly thickened and dentulated outer lips at very early
periods of growth, while many of the other Cassides are destitute of
varices, and that an operculum of C. coarctata was brought to this
country by Mr. Cuming. It is probable, however, that an increased
knowledge of facts might go far to establish the separation. C.
Testiculus, fig. 412.
CYPRÆADIA. Sw. A genus of the family "Cypræidæ," Sw. thus
described:--"Cypræform; the base contracted; the body whorl not
flattened beneath; shell cancellated; aperture of equal breadth
throughout; a few thickened, short teeth on the pillar; lip at the
base, which is not internally concave. C. cancellata, Sw. Fossil only,
differing from Trivea in its contracted base, in the inequality of its
aperture, and the equal convexity of the inner lip within." (Sw. Lardn.
Cyclop. Malac. p. 325.) Cyprædia, fig. 564.
CYPRÆLA. Sw. A genus formed for the reception of Ovulum verrucosum,
Auct. which has a circular depression at each extremity. It is the same
as the genus Calpurnus of De Montfort. Ovulum verrucosum, fig. 441.
CYPRÆOVULUM. Gray. A genus of Cypræidæ thus described, "shell like a
cowry, but front end of columella covered with regular cross-ribs, like
the rest of the base, internally produced into an acute toothed ridge.
Shell pear-shaped, cross-ridged." C. capense, fig. 444. South Africa.
CYPRICARDIA. Lam. _Fam._ Cardiacea, Lam.--_Descr._ Equivalve,
inequilateral, subquadrate, transversely elongated, with the anterior
side very short; hinge with three cardinal teeth and one remote lateral
tooth in each valve; muscular impressions two in each valve; ligament
external.--_Obs._ This genus is distinguished from Cardita by the three
cardinal teeth. The mollusca of this genus are marine. C. angulata,
fig. 125. Pacific Ocean.
CYPRINA. Lam. _Fam._ "Conques Marines," or Marine Conchacea.--_Descr._
Equivalve, inequilateral, sub-orbicular; umbones curved obliquely;
hinge with three diverging cardinal and one remote lateral teeth in
each valve; ligament external; muscular impressions two in each valve;
palleal impression having a slight posterior sinus; epidermis thick,
rough brown.--_Obs._ The Cyprinæ belong to the Northern hemisphere. The
recent species are not numerous. Fossil species are found in the
tertiary deposits. Cyprina may be known from Venus by the remote
lateral tooth and the thick epidermis. C. vulgaris, fig. 116.
CYRENA. Auct. _Fam._ Fluviatile Conchaceæ, Lam. Conchacea, Bl--_Descr._
Suborbicular, equivalve, inequilateral, ventricose, corroded at the
umbones, thick, covered with a thick epidermis; hinge with three
cardinal and two remote lateral teeth in each valve. Muscular
impressions two in each valve; palleal impression not sinuated.--_Obs._
This genus is distinguished from Venus, Cytherea and Cyprina, by having
two remote lateral teeth; and from Cyclas by the thickness of the
shell. This genus is mostly fluviatile; the recent species are
tropical, and the fossil are found in the newest formations. Fig. 113,
C. fuscata.
CYRENELLA. Desh. See CYRENOIDES.
CYRENOIDES. Joannis. CYRENELLA, Desh. _Fam._ Conques Fluviatiles,
Lam.--_Descr._ Equivalve, subequilateral, ventricose, thin, covered
with a reddish brown epidermis, corroded at the umbones, with a slight
posterior fold. Hinge thin, with three diverging cardinal teeth in each
valve, and a very slight posterior fold in the right valve. Ligament
not very tumid.--_Obs._ This fresh-water shell differs from Cyclas and
Cyrena in the want of lateral teeth, and from the latter in the
thinness of the shell. Fig. 114.
CYRTIA. Dalman. ([Greek: Kurtos], curtos, gibbose.) _Fam._ Brachiopoda,
Lam.--_Descr._ "Hinge rectilinear; with the back elevated into a
semicone or half-pyramid, the cardinal side perpendicularly
_plane_."--_Obs._ This genus of fossil Brachiopoda forms part of the
genus Spirifer, Sow. C. exporrecta, (Anomites exporrecta, Nonnull.)
fig. 204.
CYTHEREA. Lam. _Fam._ "Conques Marines," Lam.--_Descr._ Equivalve,
inæquilateral, oval, lenticular, or sub-trigonal; hinge with two or
more short, diverging cardinal teeth, and one anterior approximate
lateral tooth in each valve.--_Obs._ The Cythereæ are distinguished
from the Veneres by the lateral tooth. C. Meretrix, fig. 117, and 117,
_a. b. c. d._
DACTYLUS. Humph. MARGINELLA, Auct.
DARACIA. Gray. A subgenus of Pyrgoma, including a species which is
remarkable for the irregularity of its form. It grows upon a species of
Monticularia, and the margin takes the shape of the lobes by which it
is surrounded. The aperture is large, and completely closed by the
operculum. Daracia (Pyrgoma) Monticulariæ, fig. 489, 490.
DATE. A common name given to shells of the genus Pholas, on account of
their cylindrical form and consequent resemblance to the fruit. For the
same reason the name Pholas Dactylus has been given by Naturalists to
the species which we represent, fig. 66.
DEAD SHELL. A term used among collectors to signify that the shell has
been exposed on the sea-shore after the animal has ceased to live. A
shell in this condition is worn down by attrition, and loses its beauty
and brilliancy of colouring by being subject to the action of salt
water. A dead shell may be known by a certain hoary whiteness spread
over its surface.
DECACERA. Bl. The second family of the order Cryptodibranchiata, Bl.
containing the genera Calmar and Sepia, which have no shells.
DECADOPECTEN. Rüppell. PECTEN _Plica_, Linn. Fig. 172, having a
plicated hinge.
DECOLLATED. (_Decollari_, to be beheaded.) The apex or nucleus of some
shells being composed of a more fragile substance than the rest, has a
tendency to fall off. The reason of this probably is that the animal
withdrawing from that part, leaves it unprotected. When it falls off,
the hole is stopped up by a septum filling the cavity of the volution,
so as to exclude the air: the shell is then said to be decollated.
_Ex._ Bulinus decollatus, fig. 289.
DECUSSATED. Intersected by striæ crossing each other. _Ex._ Rissoa,
fig. 346.
DELPHINULA. Montf. (_Delphinus_, a dolphin.) _Fam._ Scalariens, Lam.
Cricostomata, Bl.--_Descr._ Orbicular, depressed, thick, rugose; whorls
few, angulated, branched at the angles; aperture pearly, rounded or
sub-quadrate; peritreme continuous, thickened; operculum horny,
composed of numerous whorls.--_Obs._ Several fossil species are found
in the tertiary deposits. D. laciniata, fig. 352. Recent species belong
to tropical climates.
DELTHYRIS. Dalman. _Fam._ Brachiopoda, Lam.--_Descr._ Hinge more or
less rounded, with distant umbones; both valves convex; with the umbo
of the largest rostrated and deltoid, with a hollow. This genus forms
part of the genus Spirifer, Sow. Fig. 205. D. Plycotes, Dalman.
DELTOID. ([Greek: D], _delta_.) Triangular.
DENDOSTREA. Sw. ([Greek: Dendron], _dendron_, tree; [Greek: ostreon],
_ostreon_, oyster.) Ostrea _Crista-galli_, and other species which are
attached to stems of sea-weed and corallines, by means of arms thrown
out from the inner surface of the lower valve. Fig. 181, Ostrea Folium.
DENTALIUM. Auct. (_Dens_, a tooth.) _Fam._ Maldania, Lam. _Order_,
Cirrobranchiata, Bl.--_Descr._ Tubular, arched, increasing in size
towards the anterior extremity, open at both ends; small aperture
sometimes having a lateral fissure; large aperture round; external
surface ribbed, striated or smooth.--_Obs._ The well known shells
composing this genus are shaped very much like an elephant's tusk, and
are not liable to be confounded with any other genus. The fossil
species are sometimes termed Dentalithes, from _dens_, a tooth, and
_lithos_, a stone. The Dentalia, being true molluscs, are not rightly
placed among the Annelides. Fig. 2, D. octogonum. Found on sandy shores
in most climates.
DENTATED. Having teeth or raised points.
DENTICULATED. (Denticulatus, Lat.) Having little teeth or raised
points.
DEPRESSED. Flattened, pressed down, as the spires of some shells.
DEXTRAL Spiral Shells. Place the point of a spiral shell towards the
eye, with its mouth downwards; if, as in most instances, the aperture
be on the right side of the axis, it is a _dextral_ shell, if
otherwise, it is _sinistral_ or _reversed_. Balea (fig. 296), and
Clausilia (fig. 295), are examples of reversed shells.
DEXTRAL Valve. Take a bivalve shell closed, place it before the eye,
with the umbones uppermost, and the posterior side, which may be known
by the ligament towards the observer, whose right side will then
correspond with the right valve of the shell.
DIADEMA. Ranz. CORONULA Diadema, Auct. fig. 17.
DIANCHORA. Sow. _Fam._ Pectinides, Lam. _Order_, Palliobranchiata,
Bl.--_Descr._ Inequivalve, attached, oblique, subtriangular; attached
valve, having an opening in the place of the umbo; the other valve
auriculated, with an obtuse umbo; hinge without teeth.--_Obs._ The
green sand fossils contained in this genus differ from Plagiostoma in
being attached. Fig. 175, D. striata.
DIAPHANOUS. ([Greek: Dia], _dia_, through; [Greek: phainô], _phaino_,
to shine.) Transparent.
DIAPHRAGM, ([Greek: diaphragma], a partition.) This term is applied to
the septa, by which the chambers of multilocular and other shells are
divided from each other.
DICERAS. Lam. ([Greek: Dis], _dis_, double; [Greek: Keras], _ceras_,
horn.) _Fam._ Chamacea, Bl. and Lam.--_Descr._ Inequilateral,
inequivalve, attached by the point of the umbo of the larger valve;
umbones prominent, spirally twisted and grooved; hinge with one large
thick tooth in the larger valve; muscular impressions, two in each
valve.--_Obs._ The prominent spiral umbones, which give rise to the
name of this genus, with the circumstance of its being attached by the
point of one of them, is sufficient to distinguish it from any other,
although it appears to approach Isocardia in some characters. In others
it will be found still more nearly to resemble Chama. In fact, from
being attached and irregular, the shells composing this genus have been
considered as Chamæ with produced umbones. The singular fossil shells
composing this genus, are found in granular limestone, near Geneva and
in Normandy. Fig. 154, D. perversum.
DIDONTA. Schum. SAXICAVA. Auct.
DIFFUSE. (_Diffundo_, to spread out, to dilate.) A term applied to the
aperture of a univalve shell, when it is spread out or widened into a
flat surface, or digitations. _Alated_ is another term used to express
the same character. Thus, the shells belonging to the family of Alatæ,
in the system of Lamarck, are _diffuse_ in the outer lip. Fig. 402 to
406.
DIGITATED. (_Digitus_, finger.) Branched out in long points, as
Ricinula, fig. 413.
DILATED. Expanded, spread. This term has the same application as
diffuse and alated, explained above. The outer lip of Rostellaria
Columbaria, fig. 403 (Hippochrenes, Montf.), will serve as an example.
DIMORPHINA. D'Orb. A genus of microscopic Foraminifera.
DIMYARIA. ([Greek: Dis], _dis_, double; [Greek: muon], _myon_, muscle.)
The first order of Conchifera, Lam. including those molluscs which have
two adductor muscles, and consequently two muscular impressions in each
valve. The Conchifera Dimyaria are divided into Crassipedes,
Tenuipedes, Lamellipedes, and Ambiguæ, fig. 44 to 155.
DIOICA. Bl. The first division of the class Paracephalophora, Bl. It is
divided into the orders Siphonobranchiata and Asiphonibranchiata, Bl.
DIPLODON. Spix. HYRIA Syrmatophora, Lam. fig. 144, and UNIO
multistriatus, Lea, are doubtfully quoted by Lea as belonging to this
apparently ill-defined genus of Nayades.
DIPSAS. Leach. A genus or sub-genus of Nayades, the distinctive
character of which is "having a linear tooth under the dorsal edge." D.
plicatus, fig. 142.
DISCINA. Lam. ORBICULA, Auct.
DISCODOMA. Sw. A sub-genus of Lucerninæ, Sw. (Helix), thus described,
"teeth none; aperture angulated; the inner lip nearly obsolete; the
outer only slightly thickened; margin carinated."
DISCOIDAL. (_Discus_, a circular plane.) A spiral shell is said to be
discoidal, when the whorls are so horizontally convolute as to form a
flattened spire. _Ex._ Planorbis, fig. 311. Orbulites Discus, fig. 479.
DISCOLITES. Montf. A genus of microscopic Foraminifera.
DISCONTINUOUS. Interrupted. _Ex._ The siphon of Nautilus is
discontinuous, i. e. its termination in one chamber does not reach to
its commencement in the next. The varices of Triton, occurring in
different parts of the whorls, do not form the continuous ridges which
characterize the generality of the Ranellæ.
DISCORBITES. Lam. A genus of microscopic Foraminifera.
DISTANT. The teeth on the hinge of a bivalve shell are said to be
distant when they are remote from the umbones.
DIVARICATED. Diverging, meeting in a point, as the teeth on the hinge
of Placuna, fig. 184.
DOLABELLA. Lam. (Dim. from _Dolabra_, a hatchet.) _Fam._ Aplysiacea,
Lam. and Bl.--_Descr._ Hatchet-shaped, arched, covered with a horny
epidermis; posteriorly attenuated, thickened, sub-spiral, anteriorly
plane, broad, thin; posterior margin reflected.--_Obs._ The two or
three species of Dolabella known are inhabitants of the Indian Ocean.
They were placed by Linnæus in his very convenient genus Bulla, under
the name B. dubia. Fig. 255, Dolabella Rumphii.