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. 



Illvva, sometimes written Tr/va, the Greek de- 

 signation of the genus Pinna, may have been ori- 

 ginally derived from ti'ivo:, the dirt, or soil, in which 

 the shells of tliis 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 admonishes 

 his friend by a gentle nij). The pinna then opens 

 his valves and admits the head of the unlucky fish, 

 who, tlms entrapped, is converted into suj)ply 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. 



