158 LIMN^AD^. 



Moll. Suec. Ter. et Fluv. p. 79. — Lam. Anim. s. Vert. (ed. Desh.) 

 vol. viii. p. 385. — Hartm. in Sturm Deutseh. Fauna, pt. 8, 

 pi. 13. — Rossmassl. Iconog. Land und Stissvv. Moll. pt. 1, 

 p. 104, pi. 2, f. 61. — Cantr. Mem. Ac. Brux. vol. xiii. p. 147. — 

 Gras, Moll. Ter. et Fluv. France, p. 59, pi. 4, f. 34. — Stein, 

 Schnecken Berlins, pi. 2, f. 20. 



Helix planorbis, Da Costa, Brit. Conch, p. 65, pi. 4, f. 12. 



Planorbis compressus, Michaud, Compl. Drap. Moll. France, p. 81, pi. 16, f. 6, 

 7,8. 



Shell rather small, extremely depressed, of a glossy 

 horn-colour, thin and transparent, regularly, closely, yet 

 not very sharply wrinkled across. Upper disk broadly and 

 rather deeply concave ; lower disk flat (more rarely con- 

 vex), occasionally, however, it is concave in the middle, in 

 which event the upper disk is almost level. Whorls 

 usually six (more rarely seven), deeply divided (especially 

 above), well rounded on the superior disk, rather flat on 

 the inferior one. Body broader above than below, not ab- 

 ruptly larger (as in a closely allied exotic species) than the 

 preceding turn, gradually shelving (for the most part with 

 little convexity), so as to form a more or less acute and 

 projecting almost basal keel-like angulation ; its upper or 

 sutural slope more or less rounded, and rather sudden 

 Mouth unarmed, oblique, subcordate, angulated by the 

 keel, decidedly broader than long, usually filling a fifth or 

 rather less of the total width, neither expanded nor stric- 

 tured externally. Diameter from a third to a fourth of 

 an inch. 



Animal pale yellowish grey, black about the head, and 

 especially between the tentacles, which are very long, pale 

 yellowish grey, and have the eyes at their bases with 

 white spaces. The foot is very short as compared with 

 the size of the shell. 



Widely distributed in England, though scarce or absent 

 in several districts. It is not included in the lists from 



