74 PINNA. 



scriptions of the several species. If we then define 

 the base to be the side opposite the hinge, con- 

 sistently with the plan in which we have ventured 

 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. 



Wvm, sometimes written ir/iw, the Greek de- 

 signation of the genus Pinna, may have been ori- 

 ginally derived from vrivog, the dirt, of soil, in which 

 the shells of this family are found. 



iElian amuses us with a story of the Pinna 

 being accompanied by a crab, who lodges and 

 boards with him ; and who, by way of return, when 

 a fish chances to swim within his precincts ad- 

 monishes his friend by a gentle nip. The Pinna 

 then opens his valves and admits the head of the 

 unlucky fish, who, thus entrapped, is converted 

 into supply for their joint larder. 



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. 



