244 LIMN>EAD^. 



Planorbis nitidus. 3IuUer, Verm. ii. 263. (part) ; Fleming, 

 B. A. 278. ; Jeffreys, Linn. Trans, xvi. 389. ; Alder, Mag. 

 Z. and B. ii. 114. ; Forbes and Hauley, B. M. iv. 161. t. 127. 

 f. 11, 12. — Helix f'ontana. Lightf. Phil. Trans. Ixxvi. 

 (1786), t. 2. f. 1.; Montagu, p. 462. t. 6. f. 6. — Tlanorbis 

 complanatus. Drap. p. 47. t. 2. f. 20 — 22. ; liossm. Icon. ii. 

 16. t. 7. f. 116. ; Brard, p. 161. t. 6. f. 4. — Planorbis lenti- 

 cularis. Kichx, Moll. Brah. 67. ; V. Alten ; Sturm, Fauna, 

 vi. 8. 16. — Planorbis fontaiiiis. Flem. Ed. Ency.y\\. %^.; 

 Turton, Man. ed. 1. 110. f. 93. ; Moq. Tund. M!^F. ii. 426. 

 t. 30. f. 10— 17. — Helix lenticularis. V. Alten, 35. t. 2. 

 f. 4. — Planorbis (Hippeutis) lenticularis, Hartm. in Sturm, 

 F'auna, t. 16. — Seginentina? fontana. Beck, Si/n, Lid. 

 123. 



In clear stagnant waters, on aquatic plants. 



Animal black. 



Shell not a quarter of an inch in diameter, of a 

 Ftg. 58. dark or whitish horn-colour, very convex 

 ^^"C^ beneath, with the centre flattened, above 

 flat, with a central umbilicus ; the outer volution 

 slightly but rather sharply carinate near the middle ; 

 the front of the shell is regularly convex, has the 

 appearance of being the proper spire, as in Segi- 

 mentina. This shell differs greatly in size and 

 colour; the larger specimens are generally much 

 the darkest, being often reddish-brown. 



e. Spire deeply umhilicated; whorls rounded before 

 and behind, not keeled, close pressed. (Bathyom- 

 phalus.) 



112. 10. Planorbis. contortus. Twisted Coil Shell. 



— Shell deeply umbilicate above, nearly flat 



beneath ; whorls eight, convex ; suture deep ; 



aperture very narrow, crescent-shaped, (t. 8. 



f. 96.) 

 Helix contorta. Linn. S. N. i. 1244. ; Montagu, p. 457. t, 25. 



