Part 43

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.

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--

1. PETRICOLA, with distinct cardinal teeth, including, Clothe, Venerirupis and Coralliophaga. Fig. 91, 92, 97.

2. 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.