LITHODOMUS. 175 



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 striae 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. Brachio- 

 poda, 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 micro- 

 scopic Foraminifera. 



LIP. See Labium and Labrum. 



LIPPISTES. Montf. A genus of microscopic Foraminifera. 



LITHODOMUS. Cuv. (Aidog, lithos, stone ; Aw/m, doma, house.) 

 Fam. Mytilacea, Lam. — Descr. Transverse, elongated, cylindri- 

 cal, 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 



