Bl.--_Descr._ Globose, glassy, transparent, with a triangular opening
at the upper part where the dorsal portion advances beyond the ventral;
ventral portion vaulted; dorsal more flat; lower extremity
tridentate.--_Obs._ The singular structures composing this genus were
formerly taken for bivalves, and named Anomia Tricuspidata, &c. They
are now known to belong to the class of molluscous animals, called
Pteropoda, from the wing-shaped organs of locomotion. A species of
Hyalæa occurs in Sicily in a fossil state. Recent species are found in
the Mediterranean, Atlantic, and Indian Oceans. Fig. 226, H.
Tridentata.
HYALINA, Studer. VITRINA, Drap.
HYALINE. (_Hyalus_, glass.) Glassy, thin, transparent--_Ex._ Carinaria
Mediterranea, fig. 488.
HYDROBRANCHIATA. Bl. The first section of the order Gasteropoda, Lam.
containing Molluscs which breathe water only; divided into the families
Tritoniana, Phyllidiana, Semi-phyllidiana, Calyptracea, Bullæana, and
Aplysiana.
HYGROMANES. Fer. A sub-division of Helix, containing H. limbata, Auct.
&c. Gray's Turton, p. 143.
HYRIA. Lam. A genus composed of species of Nayades, distinguished by
their alated dorsal margins, and lamellated lateral teeth. South
America. HYRIA corrugata, fig. 143, Hyria Syrmatophora, fig. 144.
HYRIDELLA. Sw. A genus of "Hyrianæ," Sw. described as differing from
HYRIA, Auct. in having a cardinal as well as a lateral tooth in each
valve. Sw. p. 380.
HISTRIX. Humph. RICINULA, Auct.
JANERA. Schum. A genus composed of species of Pecten, Auct. having
oblique plicæ or calli on each side of the ligamentary pit. _Ex._ P.
plica, fig. 172. Decadopecten, Rüppell.
JANTHINA. Auct. (_Janthum_, a violet.) _Fam._ Neritacea, Lam.
Oxystomata, Bl.--_Descr._ Sub-globose, thin, fragile; spire short,
consisting of few whorls; aperture angulated, at the anterior junction
of the inner and outer lips; columella tortuous, contiguous to the
axis; outer lip thin, sinuated in the centre.--_Obs._ The shells
composing this genus are celebrated for their beautiful purple colour.
The animal possesses a small vesicular process, which keeps it floating
on the surface of the water; it exudes a purple secretion when
irritated. It is occasionally floated on to the shores of most
temperate and tropical countries. Fig. 333, J. Fragilis.
JATARONUS. Adanson. CHAMA, Auct.
IBERUS. Montf. CAROCOLLA, Lam.
IBLA. Leach. _Fam._ Pedunculated Cirripedes, Lam.--_Descr._ Four
valves, posterior pair elongated, anterior pair short, triangular;
pedicle cylindrical, contracted at the base, hairy.--_Obs._ I.
Cuveriana (fig. 40) is brought from Kangaroo Island.
ICTHYOSARCOLITES. Desmarest. _Fam._ Ammonacea, Lam.--_Descr._
Chambered, slightly arcuate, laterally compressed; septa simple,
leaving triangular articulations imbricated like the thick muscles of a
fish.
JESITES. Montf. A minute fossil resembling GALEOLARIA.
ILOTES. Montf. ORBICULINA, Bl. A genus of microscopic Foraminifera.
IMBRICARIA. Schum. CONOHELIX, Sw.
IMBRICATED. (_Imbrex_, a tile.) A shell is said to be imbricated when
the superficial laminæ are arranged over each other in the manner of
tiles.
IMPERATOR. Montf. A genus composed of species of the genus TROCHUS,
Auct. with whorls angulated and stellated, having an umbilicus. _Ex._
T. Imperialis. Some of the shells named Imperator in the British Museum
belong to the genus Calcar, Montf. having no umbilicus.
IMPRESSION. See MUSCULAR IMPRESSION.
INCRASSATED. (_Crassus_, thick.) Thickened, as the hinge of Glycimeris,
fig. 67.
INCURVED. Turned inwards or bent forwards. Applied to symmetrical
shells, when the point of the apex turns towards the anterior
extremity, as in Patella. The apex of a shell is said to be incurved
when it is bent inwards, but not sufficiently so to be described as
spiral. _Ex._ Ammonoceras, Lam. fig. 477.
INDENTED. (_In_, in; _dens_, a tooth.) Exactly the reverse of DENTATED;
meaning a series of small cavities, such as might be produced by the
entrance of teeth. The cast of a dentated surface would be indented.
INEQUILATERAL. (_Æquus_, equal; _latus_, a side.) A term applied to a
bivalve shell when its extent on one side of the umbones is greater
than that on the other. When the sides are nearly equal, the term
_sub-equilateral_ is used.
INEQUIVALVE. (_in_; _æquus_, equal; _valva_, valve.) The two principal
valves differing from each other in diameter or convexity.
INFERIOR VALVE is that which is attached to sub-marine bodies. Only
applied to attached bivalves.
INFEROBRANCHIATA. Bl. The fourth family of the second section of
Paracephalophora Monoica, Bl. containing no testaceous mollusca.
INFLATED. Swelled, as Bulla, fig. 250, 252. This term can only be
applied to rotund shells of a light, thin texture. In other cases we
should use the word VENTRICOSE.
INFLECTED. Turned inwards. This term is applied to the outer lip of a
spiral shell when it turns towards the body whorl. This is the case in
Cypræa, fig. 446. See REFLECTED.
INFUNDIBULUM. Montf. (_A funnel._) A genus formed of those species of
CALYPTRÆA, Lam. which, having a spiral septum, so nearly resemble
Trochus that some authors have placed them in that genus. One species
named Patella Trochiformis. Recent from South America, fossil from the
tertiary beds. Fig. 237, 238, Calyptræa (Infundibulum) Pileus.
INNER LIP. That edge of the aperture of an univalve shell which is near
to the imaginary axis, as distinguished from the outer lip, or that
which is on the opposite side.
INOCERAMUS. Sow. _Fam._ Malleacea, Lam. Margaritacea, Bl.--_Descr._
Thick, inequivalve, sub-equilateral, triangular, deep, with the umbones
incurved; hinge formed of a series of transverse grooves.--_Obs._ The
larger valves of these fossil shells resemble the larger valve of
Gryphæa; but the hinge is quite distinct. The species described in
Mineral Conchology are found in the blue marl, at Folkstone, and in the
chalk. I. Lamarckii, (Catillus, Brong.) fig. 167.
INTERNAL CAST. The mould of a fossil shell, composed of matter which
entered the shell in a soft state, and has subsequently hardened, when,
the shell dropping off, the hardened substance which filled it is left
to represent its internal form.
INTERNAL LIGAMENT. A term used by some conchological writers signifying
that the ligament of a bivalve shell is placed within the closed part
of the hinge, so as not to be seen when the valves are shut. But the
substance, formerly called the internal ligament, is now distinguished
from the true ligament both in structure and use; and is now more
properly called the cartilage, so that when the ligament is said to be
internal, it must be understood that the internal cartilage is
unaccompanied by any ligament properly so called, and when a shell is
described as having two ligaments, as in the case of Amphidesma, it
means that the two substances are so far removed from each other in the
hinge that they are no longer confounded together.
INTERNAL SHELL is one which is enclosed in the soft parts of the
animal, as a bone is enclosed in the flesh of a human body. The Limax,
or common garden slug, which has a testaceous shield beneath its
mantle, is an instance of this.
IO. Lea. A genus composed of several species of fresh-water shells
which are considered as differing from Melaniæ in having the anterior
termination of the aperture produced into a point in some degree
resembling the caudal canals of shells belonging to the family of
Canalifera, which are marine. Io fusiformis and spinosus are described
and figured in Lea's work on the genus Unio.
JODAMIA. Defr. A genus resembling Birostrites, except that in Jodamia
one valve overwraps the other, while in Birostrites the circumference
of the valves is equal.
IPHIGENIA. Gray. A sub-genus of Clausilia, C. biplicata, &c. Auct.
Gray's Turton, p. 214.
IRIDEA. Sw. A genus of "Hyrianæ," Sw. thus described:--"Oblong ovate;
bosses small, depressed, sulcated; inner cardinal tooth placed beneath
the outer. I. granosa, _Lam._ En. Méth. 248. fig. 9."
IRIDINA. Auct. A genus belonging to the Nayades, and resembling the
ANODONTÆ, Auct. but its peculiar characteristic is that the hinge
lamina is tuberculated or crenulated in its whole length. Sowerby
unites all the genera of the family into the genus UNIO. Fig. 150, I.
Elongata.
IRREGULAR SHELLS, are those which, being attached to, or imbedded in
other marine bodies, have no constant form, but are modified in shape
according to the substances to which they are fixed, as the Chamacea,
fig. 153 to 155.
IRUS. Oken. Comprehending PANDORA, PETRICOLA, SAXICAVA, &c.
ISOCARDIA. Lam. ([Greek: Isos], _isos_, similar; [Greek: Kardia],
_cardia_, heart.) _Fam._ Cardiacea, Lam. Chamacea, Bl.--_Descr._
Cordiform, regular, equivalve, ventricose, with distant, diverging,
involute, free umbones; hinge with two compressed cardinal, and one
distant, compressed lateral teeth in each valve; ligament external,
bifid, diverging in the direction of the umbones.--_Obs._ The shells
composing this genus are remarkable for the beautiful curvature of the
diverging umbones. European and Chinese Seas. Fig. 126, I. Moltkiana.
KEEL. A flattened ridge, resembling the keel of a ship. As that on the
back of Carinaria vitrea, fig. 488, and those on the whorls of some
spiral shells. A shell characterized by a keel or keels is said to be
carinated.
KELLIA. Turton, MYA Suborbicularis, Montague.
LABIS. Oken. MONODONTA, Lam.
LABIUM, or inner lip,--is used to express that side of the aperture
which is nearest to the axis and generally contiguous to the body
whorl. The lower part of this, when sufficiently distinct from that
part which overwraps the body whorl, is called the Columella.
LABRUM, or outer lip,--is the edge of the aperture at the greatest
distance from the axis.
LACINEA. Humph. CHAMA, Lam.
LACUNA. Turt. _Fam._ Turbinacea, Lam.--_Descr._ Globose, thin, covered
with a smooth epidermis; spire short, consisting of few rapidly
increasing whorls; aperture semilunar, rounded at the extremities;
columella oblique, reflected over part of the umbilicus; umbilicus
forming a lengthened area behind the columella. Northern shores. Fig
364, L. Pallidula.
LAGENULA. Montf. A genus of microscopic Foraminifera.
LAMELLATED. (_Lamella_, a thin plate.) When the layers of which a shell
is composed, instead of being compacted into a solid mass, are
separated, overlying each other in the manner of tiles, with the edges
prominent, the structure is said to be lamellated or foliaceous.
LAMELLIBRANCHIATA. Bl. The third order of the class Acephalophora, Bl.
consisting of bivalve shells, divided into the families Ostracea,
Subostracea, Margaritacea, Mytilacea, Polydontes, Submytilacea,
Chamacea, Conchacea, Pylorides, Adesmacea.
LAMELLIPEDES. Lam. (_Lamella_, a thin plate, _pes_, a foot.) The third
section of the order Conchifera Dimyaria, containing bivalves, with the
foot of the animal broad and thin; divided into the families Conchacea,
Cardiacea, Arcacea, Trigonacea, Nayades. Fig. 111. to 152.
LAMPAS. Montf. LENTICULINA, Bl. A genus of microscopic Foraminifera.
LAMPRODOMA. Sw. A genus of "Olivinæ," Sw. thus described:--"Mitriform;
spire produced, conic; resembling MITRELLA in shape, but the suture is
channelled; the aperture effuse at the base, contracted above; lower
half of the pillar with 6 to 7 plaits. Volutella, Zool. Ill. ii.
series, pl. 40. f. 1. (_fig. 86._ )" Sw. p. 321.
LAMPROSCAPHA. Sw. A sub-genus of "Anodontinæ," Sw. thus
described:--"Shell not winged, elongate, pod-shaped; teeth none; bosses
near the anterior extremity. Tropical America only? L. ? elongata.
_Sw._ Zool. Ill. i. 176. ensiforme, _Spix._ Braz. Test. siliquosa.
Braz. Test. pygmæa. Ib." Sw. p. 381.
LAMPROSTOMA. Sw. A sub-genus of Canthorbis (Trochus), described at p.
350, Lardn. Cyclop. Malac.
LAMPUS. Humph. TEREBRATULA, Lam.
LANCEOLATE. Lengthened like a lance.
LANISTES. Montf. Reversed species of AMPULLARIA, fig. 319.
LAPLYSIA. See APLYSIA.
LAPLYSIACEA. Lam. (properly Aplysiacea) A family belonging to the first
section of the order Gasteropoda, Lam. containing the genera Aplysia
and Dolabella. Fig. 254, 255.
LARVA. Humph. FISSURELLA, Lam.
LATERAL. (_Latus_, a side.) The lateral teeth are those which, taking
their rise near the umbones, proceed to some distance towards the sides
of the shell; as distinguished from the cardinal teeth, which receive
their full developement close to the umbones. Lateral muscular
impressions are those which are placed at a distance from each other,
on the opposite sides of the shell.
LATIAXIS. Sw. A genus of "Eburninæ," Sw. corresponding with the genus
Trichotropis. Sow. (Sw. Malac. p. 306.)
LATIRUS. Montf. A genus composed of species of FUSUS, Auct. which have
an umbilicus and are turriculated.
LAURIA. Gray. A sub-genus of PUPA, containing P. umbilicata, &c.
(Gray's Turton, p. 193.)
LEGUMINARIA. Schum. A genus composed of species of SOLEN, Auct. which
have an internal longitudinal bar or rib. Fig. 61. S. Radiatus, Lam.
LEILA. Gray? Described as having the hinge edge smooth like Iridina,
but having a "sharp siphonal inflexion." (Syn. B. M. p. 142.)
LEIODOMUS. Sw. A genus of "Buccininæ," Sw. consisting of Terebra
vittata and other similar species. This genus corresponds with Bullia,
Gray.
LEIOSTOMA. Sw. A genus of "Fusinæ," Sw. thus described, "Equally
fusiform," (with Fusus) "but ventricose in the middle; shell entirely
smooth, almost polished; inner lip thickened, and vitreous; base of the
pillar very straight. Fossil only. (_fig. 75._) L. bulbiformis. En.
Méth. 428. f. 1."
LEMBULUS. Leach. A genus composed of oval species of NUCULA, resembling
N. margaritacea, fig. 137.
LENDIX. Humph. PUPA, Lam.
LENGTH. See MEASUREMENT.
LENTICULAR. (_Lens._) Of a circular, convex form, as Pectunculus, fig.
134.
LENTICULINA. Lam. A genus of microscopic Foraminifera.--_Descr._
Lenticular, sub-discoidal, compressed, convolute, symmetrical; aperture
notched; chambers few in number; visible on the exterior, radiating
from the centre of the disk.
LEPADICEA. Bl. The first family of the class Nemantopoda, Bl. This
family consists of the same animals which constitute the Pedunculated
Cirripedes of Lamarck, and part of the genus Lepas in the system of
Linnæus. It contains the genera Gymnolepas, Pentalepas, Polylepas and
Litholepas.
LEPAS. ([Greek: Lepas], _lepas_, a rock.) The Linnæan name Lepas
contains all the Cirripedes or Multivalves, the different kinds of
which are not distinguished in the accounts given by early writers of
the habits of the animals. (Fig. 14 to 43.) It was formerly applied to
the Limpets or Patella. In fact, the ancient definition was "Concha
petræ adhærens," and would apply to any shells attached to rocks.
LEPTÆNA. Dalman. A genus belonging to the Brachiopoda; and thus
described:--"Hinge compressed, rectilinear, frequently exceeding the
width of the shell." It forms part of the genus Producta, Sow. Fig.
206, L. depressa.
LEPTOCONCHUS. Rüppell. ([Greek: Leptos], _leptus_, thin; [Greek:
Konchos], _conchos_, shell.) This shell resembles a young MAGILUS in
general appearance, although the animal is said to differ. In the young
Magilus also, the inner lip is reflected over the body whorl, which is
not the case in Leptoconchus. Red Sea. Fig. 11.
LEPTOCONUS. Sw. A sub-genus of Conus, consisting of Conus grandis,
amadis, duplicatus, Australis, &c. Sw. p. 312.
LEPTOLIMNEA. Sw. A sub-genus of Limnea, described as being nearly
cylindrical. Limnea elongata, Sow. Gen. fig. 6.
LEPTON. Turton. SOLEN Squamosus, Montague, and other species described
as "flat, nearly orbicular, equivalve, inequilateral, a little open at
the sides. Hinge of one valve with a single tooth, and a transverse
linear lateral one on each side; of the other valve, with a cavity in
the middle and a transverse deeply cloven lateral tooth each side, the
segments of which divaricate from the beak." To represent this genus we
have figured L. Squamosum in the plates, fig. 62. British.
LEPTOSPIRA. Sw. A sub-genus of Bulinus, thus described: "Spire
excessively long, sub-cylindrical; body whorl largest; outer lip
thickened; aperture oval; no teeth, striata, _Sw._ Chem. 135. f. 1226.
signata _Sw._" Sw. p. 335.
LEUCOSTOMA. Sw. A genus of "Achatina," Sw. described as resembling
Achatinella, but having a "thick pad" at the top of the "upper lip,"
and another over the base. L. variegata, Sw. Lardn. Cyclop. Malac. fig.
24. p. 172.
LEUCOTUS. Sw. A sub-genus of Natica, described as intermediate between
Sigaretus and Lacuna. SIGARETUS _cancellatus_, Lam. (Sw. Malac. p.
346.)
LICIUM. Humph. OVULA, Lam. (Ovulum.)
LIGAMENT. (From _Ligo_, to bind.) The true ligament is always external,
and serves the purpose of binding the two valves of a shell together
externally by the posterior dorsal margins. There is another substance,
called by Gray the _Cartilage_, which is elastic and of a condensed
fibrous structure, placed within the ligament, either close to it, or
at a more interior part of the shell; it is sometimes contained in a
pit, formed for its reception, in the centre of the hinge. This
substance, being elastic, keeps the valves open, unless drawn together
by the counteracting force of the adductor muscles. When conchologists
speak of a shell as having the ligament external, the real meaning is
that these two substances are so close together as in appearance to
constitute one body placed outside the shell so as to be seen when the
valves are closed. When two ligaments are spoken of, as in Amphidesma,
the meaning is that the cartilage occupies a separate place on the
hinge.
LIGAMENTIFEROUS. (_Ligamentum_, a ligament, _fero_, to bear.) Having or
containing the ligament, as the cardinal pit in Mya, fig. 71.
LIGULA. Leach. A genus containing the more rounded and less gaping
species of LUTRARIA, Auct. Fig. 77, Lutraria Papyracea.
LIGULATE. (_Ligula_, a slip, a shoe-latchet.) Thin, slender, like a
slip, or neck of any thing, as the anterior muscular impression of
Lucina, fig. 104.
LIGUMIA. Sw. A sub-genus of Unio, thus described:--"Very long and
pod-shaped; bosses depressed; cardinal teeth moderate. S. recta. Lam.
vi. 1. p. 74." Sw. p. 378.
LIGUUS. Montf. A genus containing species of ACHATINA, Auct. which have
rounded apertures and lengthened spires, differing from his POLYPHEMI,
which have lengthened apertures. A. virginea, Auct. fig. 286, is the
type of this genus.
LIMA. Brug. (_Lima_, a file.) _Fam._ Pectinides, Lam. Subostracea,
Bl.--_Descr._ Equivalve, inequilateral, compressed,
oblique-auriculated, oval, radiately ribbed or striated, imbricated,
covered with a light brown epidermis; hinge with a triangular disc
between the umbones, divided in the centre by a triangular ligamentary
pit without teeth; muscular impression one, sublateral,
sub-orbicular.--_Obs._ The shells thus described are marine, two or
three species being found on our coasts, and fossil species occurring
in Lias, inferior Oolite, Calcaire-grossiér, &c. They differ from
Pecten in having a wide hiatus for the passage of a byssus, by which
they are occasionally attached, and also in the triangular disc, which
separates the umbones. The animal makes use of the valves of his shell
as natatory organs, working them like fins or paddles, and by this
means proceeding at a rapid rate through the waters. L. Squamosa, fig.
174.
LIMACINA. Cuv. (_Limax_, a snail.) _Fam._ Pteropoda, Lam.--_Descr._
Papyraceous, fragile, planorbicular, sub-carinated, obliquely
convolute; spiral side rather prominent, the other side umbilicated;
aperture large, entire, not modified, peristome sharp.--_Obs._ This is
SPIRATELLA, Bl. The shell figured as Limacina in Sowerby's Genera,
under "pteropoda," is an _Atlanta_. Our representation of Spiratella
Limacinea, fig. 224. is copied from Blainville.
LIMACINEA. Lam. A family of the order Gasteropoda, Lam. including the
following
1. CRYPTELLA. Spire mammillated; a septum. Fig. 256.
2. PARMACELLA. Flat, haliotoid, spiral. Fig. 257, 258.
3. TESTACELLUS. Sub-spiral. Fig. 261.
4. LIMAX. Incomplete. Fig. 259.
5. PLECTROPHORUS. Conical. Fig. 260.
6. VITRINA. Heliciform, hyaline. Fig. 262, 263.
LIMACINEA. Bl. The third family of the order Pulmobranchiata, Bl.
Described as containing shells very variable in form, most frequently
inclining to globular or oval; the apex always obtuse; aperture
variable, but never emarginated. All the Limacinea are phytophagous and
terrestrial. This family answers to the genus Helix of Linnæus and to
the Colimacea of Lamarck, leaving out the Auriculacea. It contains the
genera Succinea, Bulinus, Achatina, Clausilia, Pupa, Partula, Helix,
Vitrina, Testacella, Limacella, Limax.
LIMAX. _Lam._ Limacinea, Lam. and Bl.--_Descr._ Internal irregular,
sub-quadrate, scutiform, crystalline; apex rounded, indistinct;
epidermis, light brown, thin, extending beyond the margin.--_Obs._ The
shell is placed under the scutellum of the common garden slug. Fig. 25,
L. Antiquorum.
LIMNACEA. Bl. The first family of the order Pulmobranchiata, Bl. The
shells of this family are described as thin, with the outer lip always
sharp. It contains the genera Limnea, Physa, Planorbis.
LIMNEANA. Lam. A family of the order Trachelipoda, Lam. containing the
following genera:--
1. LIMNÆA. Spire produced; including _Physa_. Fig. 308 to 310.
2. PLANORBIS. Spire orbicular; including _Planaria_. Fig. 311, 312.
LIMNEA. Lam. ([Greek: Limnas], _limnas_, lacustrine.) _Fam._ Limnacea,
Lam. and Bl.--_Descr._ Oblong, light, thin; spire variable in length,
acute; last whorl large, aperture large, longitudinal, entire; inner
lip spread over a portion of the last whorl; columella forming an
oblique fold; outer lip rounded at each extremity, thin.--_Obs._ These
light horn-coloured shells are common in standing pools, ponds and
ditches, in various parts of Europe. They resemble the Amber shell
(Succinea) in shape, but the animal of the latter is amphibious, and
the shell of a bright amber colour. L. Stagnalis, fig. 308. L.
auricularia, fig. 309. (RADIX, Montf.) The reversed species have been
separated under the name Physa, fig. 310. Other generic names have been
given to other species.
LINES OF GROWTH. The concentric striæ or lines formed by the edges of
the successive layers of shelly matter deposited by the animal by which
it increases the shell. The outer edge of the aperture is always the
last line of growth.
LINGUIFORM. (_Lingua_, tongue; _forma_, form.) Tongue-shaped.
LINGULA. Lam. (Dim. from _lingua_, tongue.) _Fam._ Brachiopoda, Lam.
Palliobranchiata, Bl.--_Descr._ Equivalve, oblong, depressed, thin,
equilateral, gaping and pointed at the umbones, gaping and truncate or
trilobate at the opposite extremities, attached by a fleshy pedicule
fixed to the umbones.--_Obs._ This is the only bivalve shell which is
pedunculated, in which respect it constitutes a singular anomaly. The
ancient writers, seeing the valves separate, placed it in their systems
under the name Patella Unguis. There are several recent species found
in the Moluccas, and some fossils in sandy indurated marl, and in
alluvium of Suffolk. L. Anatina, fig. 219, is so named from its
resemblance to a duck's bill.
LINGULINA. D'Orb. A genus of microscopic Foraminifera.
LINTHURIS. Montf. Conch. Syst. 2. 154. A genus of microscopic
Foraminifera.
LIP. See LABIUM and LABRUM.
LIPPISTES. Montf. A genus of microscopic Foraminifera.