A Conchological Manual by George Brettingham Sowerby (best interesting books to read txt) 📕

   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.

   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

   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.

   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