449 



HeJix cornea. Den. Br. Shells, ii. t, S9. f. ]. 



Tiirt. Lin. iv. p. 510. 

 Helix: nana. Br. Zool. t. S3, f. 125. (young.) 



Helix Cornu Arietis. Da Cofta. p. 60. t. 4. f. 13. 

 Helix fimiJIs. Gmd. Syfl. p. 3625 .? 



Planorbis^iimilis. Midler Verm. ii. p. 166. No. 332? 



Schroeter Flujjconch. p. 245. No. 58. 



H. with a deprefled, fub-pellucid fliell, of a brown, 

 or cinereous, fometimes rufous horn-colour, lighteft on 

 the under part: volutions four, rounded, and feparated 

 by a deep fpiral line: apex mucli deprelTed, forming a 

 confiderable cavity : the under part nearly flat, or a little 

 concave : it is confiderably wrinkled acrofs the voluti- 

 ons, and has fometimes one or two larger, antiquated 

 ridges: aperture almoflequi-lateral, fub-lunated; margin 

 thin, a little oblique downwards ; inner lip a little fpread 

 on the body whirl, whitifli at the angles, and round the 

 inner margin. Diameter ufually about an inch, rarely 

 an inch and a quarter. 



This, the largell fpecies of our deprefled Helices, is 

 not uncommon in fome of our flow rivers, and flagnant 

 waters, efpecially in old water courfes and drains in low 

 fwampy fituations ; but is certainly more local than Da 

 Costa defcribes it to be; who fays, it is common in all 

 ponds, rivers, and lakes throughout England. This cer- 

 tainly is far from being the cafe; however, it is fufficient- 

 ly plentiful in fome parts, though we have never found 



M m m it 



