175 



inhabit both fait and frefh-'^vater, that might readily be 

 miflaken for minute fliells : one of which is figured in 

 Tab. 14 No. 8. of this work by miftake, net having an op- 

 portunity of examining the animal till after the plate was 

 engraved. 



This, and another fpecies o^ Monoculus in every refpeft 

 like it, but of a longer and morecylindric fliape, is found 

 on Oyjlers on the fouth coalt of DevonJJiire ; and on the 

 h\\ffus o^ the Pinna ingens ; a general repofitory for Mo- 

 noculi and very minute (hells, efpecially Nautili and 

 Vermiculi. 



Thefe two fpecies of Monoculus are extremely fmooth, 

 and gloffy, of a blufh-colour when alive, or frefh, and 

 opaque yellowifli-white when dead; and are diflinguiflied 

 from any other, by the remarkable Jinus in front, near 

 the end, through which is a groove or channel ; but this 

 perforation is only to be diflinguiflied when the valves are 

 laid open. Had Gmelin made any mention of this fingular 

 flrufturc, we fhould have been inclined to think thefe were 

 his M. luteus and M. Jlavidus :* but as we have not at 

 prefent an opportunity of confulting the figures of thofe 

 infefls given in iMuller, mufl; leave the matter to be de- 

 cided by entomologifls ; craving pardon for this digreffion. 



We cannot however quit the fubjeft without remarking, 

 that the fared diftinftion between the fliells of the bivalve 



Adonoculi 



* The rintenna indeed of the one figured' in this work was not fimplc, buf 

 compofed of fevcral briilies. 



