18 



with a thin skin, which is sometimes of a blackish 

 colour ; beaks minute, with the region about them 

 often decorticated. 

 We are inclined to think that all our supposed species 

 of this Genus may be justly resolved into one. 

 varying in their outline, consistence, and colour, 

 from age and local circumstances, and that the 

 angular or winged appearance gradually lessens 

 and forms a regular slope as it advances to its full 

 growth ; for who has seen the young of Anodon 

 cygneus without the angle or wing ? Thus we can 

 only consider the Anodon paludosus of Turton's 

 Bivalves, the Mytilus atagnalis of Sowerby's Mis- 

 cellany, and the Mytilus Avonensis of Montagu, 

 as mere local varieties. Our present figure repre- 

 sents the shell as having nearly, but not quite, lost 

 its angular outline. 



