86 PINNA. 



ment adheres ought not to be considered as the 

 hinge : if so, the length of the shell will be less 

 than its breadth ; which is contrary to the Linnsan 

 descriptions of the several species. If we then 

 define the base to be the side opposite the hinge, 

 consistently with the plan in which we have ven- 

 tured to differ from the great Swedish naturalist, 

 the Pinna will be supposed to rest on one end, and 

 not to stand upon its apex. Such a supposition 

 is at least justified by the analogy of the Solen_, 

 which is known to perforate the sand laterally. 

 To TTivva, a wing or feather, the shape is so nearly 

 similar, that we cannot doubt the derivation of the 

 generic name. 



From this genus, so equivocally placed between 

 the two divisions of Testacea, consisting of one, 

 and of two parts, it is but a short remove to the 

 next link in the admirable chain of Nature, 



