488 BULLA. 



Turbo adversus. Da Costa Brit. Conch, p. 96. t. 5. f. 6* 



Helix bulloides. Donovan, v. t. lf)8. f. 2. Maton and 



Racket, in Lin. Trans, viii. p. 223. 

 Lister Anim. Ang. t. 2 f. 25, and Conch, t. 134. f. 34. 



Gualter, t. 5. f. CC. Favanne, t. 61. f. E 9- 

 Inhabits rivers and pools on aquatic plants in Great Britain, and 



many other parts of Europe. 

 Shell about half an inch long, and half as broad, extremely 

 brittle, horn-coloured, and pellucid, with reversed whirls, of 

 which the lowest is inflated and constitutes almost the whole 

 of the shell. Bruguiere has confounded Bulla rivalis with 

 this species. 



rivalis. 38. Shell oval, pellucid, with the whirls 

 reversed; spire prominent, acute; aperture 

 ovate-oblong. 



Bulla rivalis. Maton and Racket, in Lin. Trans, viii. p. 

 126'. t. 4. f. 2. Montagu, Supp. p. 97. 



Bulla fontinalis. Schroeter Flussconch. p. 269- t. 6. f. 16, 

 a and b. Chemnitz, ix. p. 30. t. 103. f. 877 and 878. 



La Bulle aquatique. Geoffroy, p. 101. No. 10. t. 3. 



Favanne, t. 61. f. E 6. 

 Inhabits pools and rivers in Great Britain, and other parts of 



Europe. West Indies. Montagu. 

 This shell is intermediate between B. fontinalis and B. Hyp- 



norum, and is readily distinguished from the former by the 



spire being more acute and produced, and the lower part of 



the aperture more contracted; and from the latter by having 



the spire more conical, and more acutely pointed. Mr. 



Montagu says, that in the West Indies it grows to twice the 



size of British shells. 



HYPNORum. 39. Shell ovate, pellucid, with the 

 whirls reversed; spire prominent; aperture 

 ovate lanceolate. 

 Bulla Hypnorum. Lin. Syst. Nat. p. 1185. Chemnitz, 

 ix. p. 34. t. 103. f. 882 and 883, a, h, and c. Gmelin, 

 p. 3428. Montagu Test. p. 228. Maton and Racket, 

 in Lin. Trans, viii. p. 127. t. 4, f. 3. Dorset Catalogue, 

 p. 43. t. 18. f. 20. 

 Planorbis turritus. Muller Verm. ii. p. 169. 

 Bulimus Hypnorum. Bruguiere in Encyclopedic Metho-* 



dique, p. 301. 

 Helix marmorata. Gmelin, p. 3665. 



