A Conchological Manual, George Brettingham Sowerby [little readers .TXT] 📗

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.

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

 

CRYPTELLA. Spire mammillated; a septum. Fig. 256.

 

PARMACELLA. Flat, haliotoid, spiral. Fig. 257, 258.

 

TESTACELLUS. Sub-spiral. Fig. 261.

 

LIMAX. Incomplete. Fig. 259.

 

PLECTROPHORUS. Conical. Fig. 260.

 

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,

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:--

 

LIMNÆA. Spire produced; including _Physa_. Fig. 308 to 310.

 

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.

 

   LITHODOMUS. Cuv. ([Greek: Lithos], _lithos_, stone; [Greek: Dôma],

   _doma_, house.) _Fam._ Mytilacea, Lam.--_Descr._ Transverse, elongated,

   cylindrical, equivalve, with the extremities rounded, and the posterior

   extremity rostrated; umbones not prominent, terminal; hinge straight,

   destitute of teeth; ligament linear, most conspicuous within; muscular

   impressions two.--_Obs._ The shells composing this genus differ from

   Modiola, not only in the cylindrical form, but also in the circumstance

   from which the generic name is derived, i. e. of their living in

   stones. Thus, while the form and structure of the shell bring it near

   the Mytili or Muscle shells, the habits of the animal cause it to

   approach the Lithophagi, or rock-eating molluscs of Lamarck. L.

   Dactylus (fig. 161,) is the Mytilus Lithophagus of ancient authors.

 

   LITHOLEPAS. Bl. ([Greek: Lithos], _lithos_, stone, [Greek: lepas],

   _lepas_, rock.) De Blainville's name for LITHOTRYA, Sow.

 

   LITHOPHAGIDÆ. Lam. ([Greek: Lithos], _lithos_, stone; [Greek: Phagô],

   _phago_, eat or gnaw.) A family of the Conchifera Dimyaria, Lam.

   consisting of terebrating bivalves, gaping anteriorly, having no

   accessary valves; and containing the genera Saxicava, Petricola,

   Venerupis, to which are added other genera enumerated in explanation of

   figures 91 to 97. Notwithstanding the numerous genera which have been

   created, I think that the most convenient arrangement will be to reduce

   them to two, thus--

 

PETRICOLA, with distinct cardinal teeth, including, Clothe,

       Venerirupis and Coralliophaga. Fig. 91, 92, 97.

 

SAXICAVA, without teeth, including Biapholius, Hiatella,

       Sphænia, Byssomya, and Thracia. Fig. 93 to 96.

 

   LITHOTRYA. G. B. Sowerby. ([Greek: Lithos], _lithos_, stone; [Greek:

   truo], _truo_, to bore through.) _Fam._ Pedunculated Cirripedes,

   Lam.--_Descr._ Eight unequal valves, forming a laterally compressed

   cone, the lower central valves being very minute; pedicle fleshy, scaly

   at the upper extremity; fixed at the base in a patelliform shelly

   support.--_Obs._ This genus derives its name from the power possessed

   by the animal of making dwelling holes in stones or pieces of rock. The

   remarkable shelly cups at the base of the pedicle is regarded as

   analogous to the shelly base of the Balanus, so that this genus would

   form an intermediate link between the Sessile and Pedunculated

   Cirripedes of Lamarck. Fig. 39, L. dorsalis. West India Islands.

 

   LITIOPA. Ranz. _Fam._ Turbinacea, Lam.--_Descr._ "Shell not very thick,

   horny, with a slight epidermis, rather transparent, conical, with

   whorls somewhat rounded; the last being larger than all the rest

   together; with the apex pointed, longitudinally grooved; aperture oval,

   larger anteriorly than posteriorly, with the lips disunited, the right

   lip simple, separated from the left by a rather indistinct notch, or a

   slight emargination in the contour. The left lip slightly reflected

   backwards, so as to form a kind of salient margin with the anterior

   extremity of the columella, which is united, rounded, arcuated and

   slightly truncated at the anterior."--_Obs._ The Molluscous animals,

   whose shells are thus described, are found in the Mediterranean, and

   are remarkable for the power of suspending themselves from the sea-weed

   on which they live, by a thread resembling a spider's web. The general

   appearance of the shell presents a medium between Phasianella and

   Littorina, but it is apparently destitute of an operculum.

 

   LITTORINA. Fer. (_Littus_, the sea-shore.) _Fam._ Turbinacea,

   Lam.--_Descr._ Turbinated, thick; spire acuminated, consisting of few

   whorls, about one third of the axis in length; aperture entire, large,

   rounded anteriorly; outer lip thickened within, acute; columella rather

   flattened; operculum horny, spiral, with rapidly increasing

   volutions.--_Obs._ The shells composing this genus are known from Turbo

   and Phasianella by the horny operculum; and from Trochus, which has

   also a horny operculum, by the small number of the whorls. The

   Littorinæ, among which may be enumerated the common Periwinkle, are, as

   the name implies, found on sea shores, feeding upon seaweed, in all

   parts of the world. Fig. 363, _L. Vulgaris_.

 

   LITUACEA. Bl. The second family of Polythalamacea. Bl. The shells are

   described as chambered, symmetrical, convolute in part of their extent,

   but constantly straight towards the termination. The genus Spirula,

   which is admitted into this family, does not properly belong to it, any

   more than to the Lituolæ of Lamarck, in which it is also placed. It

   does not agree with the descriptions of either. This family partly

   corresponds with the "Lituolées," Lam. and contains the genera Lituola,

   Ichthyosarcolites, Spirula, Hamites and Ammonoceras.

 

   LITUACEA. Lam. A family of the order Polythalamous Cephalopoda, Lam.

   containing the genus Spirula, fig. 471.

 

   LITUITUS. Montf. SPIROLINA, Lam. Microscopic.

 

   LITUOLA. Lam. A genus of microscopic Foraminifera.

 

   LITUOLÆ. Lam. The third family of Polythalamous Cephalopoda, Lam. the

   shells of which are described as partially spiral, the last whorl

   continuing in a straight line. The transverse septa which divide the

   chambers, are in general pierced by a siphon which breaks itself off

   before it reaches the succeeding septum. This family contains the

   genera of microscopic Foraminifera Lituola and Spirolina. The genus

   Spirula, also placed in this family, does not by any means agree with

   Lamarck's definitions "the last whorl continuing in a straight line."

 

   LITUUS. Humph. CYCLOSTOMA? Lam.

 

   LIVID. (From _lividus_.) Of a pale, dull, blue colour. The adjective is

   sometimes used as a specific name. _Ex._ Conus _lividus_, Sanguinolaria

   _livida_.

 

   LOBARIA. Schum. SANGUINOLARIA rosea, Lam. (fig. 98) and other similar

   species.

 

   LOBATE or LOBED. Divided into parts.

 

   LOBATULA. Fleming. A genus composed of two very minute species of

   chambered shells. Serpula lobata and S. concamerata, Mont. Test. Brit.

   515.

 

   LOMASTOMA. Rafinesque. An imperfectly defined genus, probably belonging

   to the Limnacea.

 

   LONGITUDINAL. Lengthwise. Longitudinal striæ, ribs, &c. are those which

   radiate from the apex and follow the spiral direction of the whorls, in

   spiral shells; and from the umbo to the ventral margin in bivalves. The

   term "decourantes" is employed by French conchologists. The bands in

   Achatina, fig. 286, are longitudinal or spiral.

 

   LORIPEDES. Poli. A genus composed of species of LUCINA, Auct. in which

   the lunules are not prominent.

 

   LOTORIUM. Montf. A genus composed of species of TRITON, Auct. in which

   the aperture is effuse. T. Lotorium, fig. 400.

 

   LOTTIA. Gray. PATELLOIDA, Quoy and Gaimard.

 

   LUCERNA. Humph. A generic name applied to some species of Helix

   included in De Ferussac's sub-genus Helicogena.

 

   LUCERNELLA. Sw. A genus of "Lucerninæ," Sw. thus described: "Teeth on

   both sides of the aperture; surface regularly and distinctly striated.

   Circumference convex."

 

 LUCIDULA. Sw. A sub-genus of Lucerna, Humph. thus described: "Aperture

   transverse, both lips much thickened and united; the outer with

   marginal obsolete teeth at the base; umbilicus closed.