BIVALVES. 67 
peculiar instincts of the animal inhabitants of the 
Cardium, Tellina, and Venus, excepting that they are 
admirably adapted to the various stations which they 
are designed to occupy. The two former inhabit the 
American, Indian, and Atlantic oceans; the Mediter- 
ranean, Caspian, and Indian seas. The latter are 
found in every part of the known world, and furnish 
a constant supply of food to marine animals, and 
birds of various descriptions. 
In another species, the Pinna, Finshell,* or Sea- 
wing, a beautiful and well known genus, we shall 
shortly have occasion to observe a most extraordinary 
compensation, not resulting from any peculiarity in 
the structure of the animal itself, but supplied by the 
deficiencies of another. At least twenty different 
species are included under this division; and here it 
is not unworthy of remark, that however different 
individuals may vary in size and colour, the usual 
form of their testaceous coatings uniformly resembles 
that of the larger species of Muscles, being long and 
tapering towards the opposite extremity. They are, 
also, generally brittle and horn-like, and are occa- 
sionally enriched with a steel-like blue, or copper 
* Pinna, or Piuné, is the Greek name for this fish: it was 
eaten by the ancients, and occasionally called the Naker, 
Naire, or Nacker; a word, the meaning of which seems un- 
known. 
