LIMACINEA. 183 



LIGrUUS. Montf. 1810. A genus containing species of Acha- 

 TiNA, Auct. which have rounded apertures and lengthened 

 spires, differing from his Poltphemi, which have lengthened 

 apertures. A. virginea, Auct. fig. 286, is the type of this genus. 



LIMA. Brug. 1797. (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, siib- 

 lateral, 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-grossier, &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 for swimming, working them 

 like fins or paddles, and by this means proceeding at a rapid 

 rate through the waters. The Monograph of this genus in the 

 Author's Thesaurus Conchyliorum contains 13 species. Plates 

 21, 22. L. Squamosa, PL x. fig. 174. 



LIMACINA. Cuv. (Limax, a snail.) Fam. Pteropoda, Lam. — 

 Beser. Papyraceous, fragile, planorbicular, sub-carinated, ob- 

 liquely convolute ; spiral side rather prominent, the other side 

 umbilicated ; aperture large, entire, not modified, peristome 

 sharp. — Obs. This is Spieatella, B1. The shell figured as 

 Limacina in Sowerby's Grenera, 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 genera : — 



1. CetptelIjA. Spire mammillated ; a septum. Fig. 256. 



2. Paemacella. Flat, haliotoid, spiral. Fig. 257, 258. 



3. Testacelltjs. Sub-spiral. Fig. 261. 



4. Limax. Incomplete. Fig. 259. 



5. Plecteophoeus. Conical. Fig. 260. 



