PLATE LXXVII. 



Chama inaequilatera, lsevis, crassa, subalbida. Gualt. I. Conch, tab. 

 S5.Jig. B. 



Da Costa notices a material error amongst the synonyms Lin- 

 naeus has given with his description of Venus Mercenaria. The 

 Venus Mercenaria of Linnsus is the shell called North American 

 Clam, and of which the Wampum, or indian money, is made; this 

 is not the species found on our coast and figured by Lister, p. 

 173. as Linnaeus imagined, but a shell altogether distinct; the 

 English species Lister notices, is the true Venus Islandica of the 

 Linnaean Systema Nature. 



This error has misled Pennant, who confounds the North American 

 kind with our species, at least as a variety having a purple tinge 

 within it. Gmelin was aware of this mistake, for in his edition 

 of the Systema Naturae, both the plates and descriptions of Pen- 

 nant and Da Costa are referred to in the synonyms of Venus Islandica. 



This shell is perfectly white when fine, and is thickly covered 

 with a fibrous epidermis of a black, or brownish colour. Found 

 on several of our coasts. Da Costa mentions Northumberland, 

 Yorkshire, Lancashire, Dorsetshire, Caernarvonshire, and other 

 shores of Wales. Aberdeenshire, and the islands of Orkney, &c, 

 in Scotland. 



