790 TROCHUS. 



whirls, with a prominent transverse ridge at the base of each , 

 the colour is livid white. 



BIDENS. 74. Shell sub-conical, somewhat keeled, 

 with eight finely striated whirls, and the base 

 convex; aperture narrow, and the outer lip 

 two-toothed and reflected. 



Trochus bidens. Chemnitz, ix. part 2. p. 50. 1. 122. f. 1052. 

 Helix bidentata. Gmelin, p. 3642. 



Inhabits the Botanic Garden at Strasburgh. Chemnitz. 



This shell appears, by Chemnitz's figures, to be rather smaller, 

 but nearly of the same form as T. terrestris, and is said to 

 be variegated with alternately white and pale yellowish trans- 

 verse bands. 



fRAGiLis. 75. Shell ovate, thin, brittle, and wax- 

 coloured ; body-whirl large, with a brown 

 band in the middle, and the aperture sub- 

 lunar. 



Trochus fragilis. Gmelin, p. 3577. 



Trochus globosus, anfractibus tribus acuminatus. Schroeter 



Fluss. p. 281. 

 TTOchus, No. 190. Schroeter EinL i. p. 754. t. 3. f. 16. 



Inhabits 



Schroeter's figure measures about a quarter of an inch both in 

 length and breadth, and is shaped somewhat like Turbo lit- 

 toreus, but has the body-whirl clasping the second at the 

 aperture, in the manner of a Helix, to which Genus it pro- 

 bably ought to be removed. 



CARINATUS. 76. Shell obtusely pyramidal, with 

 four whirls, and a transverse rib round the 

 body-whirl ; aperture roundish, and the um- 

 bilicus pervious. 



Trochus carinatus. Chemnitz, ix. part 2. p. 50. t. 122. f. 



1501. 

 Trochus callosus. Gmelin, p. 3577. 

 Trochus elongatus carinatus et umbilicatus. Schroeter 



Fluss. p. 282. t. 6. f. 10. 

 Trochus, No. 191. Schroeter Finl. i. p. 754. 

 Helix pervia. Gmelin, p. 3640, 

 Helix, No. 241. Schroeter EinL ii. p. 245. 

 Nerita Trochus. Midler Ferm. ii. p. 176. 



