130 



Length one eighth of an inch ; breadth one third its lengtli. 



This rare flicll, from the coaii of Devon, muft not be con- 

 founded with T.femijlnatus, which is vaftly broader in pro- 

 jWtion, and is deftitute of the tooth. 



BiDENS. Tiuba nigricans. Liu. Trans, viii. p. ISO. 



p. 357. I'ldl. Hutch. Dorset, t. 19. f. 10. 



Nothing has caufed more perplexity in concliology than 

 the confufion of the feveral fpecies of heteroftrophon Turbo. 

 When we confider that there is a degree of fimilitude in their 

 fliape, which, together with the circumftance of their fpires 

 turning contrary to mofi: other fliells, our furprife will ceafe 

 that they Ihould be confounded by thofe who could not bring 

 the whole together for comparifon. 



So great has been the diverfity of opinion with refpe6l to 

 determining which of tliefe are the two reverfed fliells def- 

 cribed by Linn^us, under the titles of hidens and perverfus^ 

 that fcarcely two writers have agreed upon the fubjedt, each 

 referring to one or other of the Litinaan fliells for any of 

 the reverfed fpecies that occurred. 



The authors of the Defcriptive Catalogue of Britijh TeJtScfa 

 appear to have difcovered a fliell in the Pulteney cabinet that 

 leems to accord with the hinncean defcription of hidens better 

 than any other, as being fmooth, and fub-crenated only in 

 the futures ; and which we are informed the Doctor noteff 



as 



