PLATE LIV. 



We have observed, that this species is in general discoloured, and 

 deeply tinged w^ith brown or yellov^^ ; when fine it is whitish, sleek, 

 and covered with an epidermis. 



It is found on most of our coasts, yet it is by no means common. 

 Da Costa notes it from Yorkshire, Northumberland, DorsetshirCj 

 Cornwall, Carnarvonshire, aijd the Orkneys. 



