74 
PINNA. 
Rcriptions 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. 
Uhva, sometimes written cr/t^a, the Greek de- 
signation of the genus Pinna, may have been ori- 
ginally derived from <r'mg, the dirt, or 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 i 
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. 
