244 LIMNJEADJE. 



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

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

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

 f. 11, 12. Helix fontana. Lightf. Phil Trans. Ixxvi. 

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

 complanatus. Drop. p. 47. t. 2. f. 20 22. ; Eossm. Icon. ii. 

 16. t. 7. f. 116. ; Brard,v>. 161. t. 6. f. 4. Planorbis lenti- 

 cularis. Kickx, Moll. Brab. 67. ; V. Alien ; Sturm, Fauna, 

 vi. 8. 16. Planorbis fontanus. Flem. Ed. Ency. vii. 69. ; 

 Turton, Man. ed. 1. 110. f. 93.; Moq. Tand. M. F. ii. 426. 

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

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

 Fauna, t. 16. Seginentina? fontana. Beck, Sun. Ind. 

 123. 



In clear stagnant waters, on aquatic plants. 



Animal black. 



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

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

 ^^ 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 Seg- 

 mentina. This shell differs greatly in size and 

 colour; the larger specimens are generally much 

 the darkest, being often reddish-brown. 



e. Spire deeply umbilicated ; 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. 



