MOLLUSCA. 437 
breed on the bed ; arid, by gradually occupying all the 
places on which the spawn should be cast, will destroy 
the Oysters. 
The Oyster has been represented, by many authors, as 
an animal destitute not only of motion, but of every spe- 
cies of sensation. It is able, however, to perform move- 
ments which are perfectly consonant to its wants, to the 
dangers it apprehends, and to the enemies by which it is 
attacked. The gills, through which the Oyster breathes, 
are what is commonly called the beard ; and they are very 
indigestible. The scallop is nearly allied to the Oyster. 
THE COMMON COCKLE. (Cardium edule.) 
FEW of our shell-fish are more common, in inlets and 
bays near the mouths of rivers, than these. In such situ- 
ations they are usually found immersed at the depth of 
two or three inches in the sand, the place of each being 
marked by a small, circular, depressed spot. When they 
open their shells, the entrance into them is protected by a 
soft membrane, which entirely closes up the front, except 
in two places, at each of which there is a small, yellow, 
and fringed tube. It is by means of these tubes the ani- 
mals receive and eject the water which conveys to their 
body the nutriment necessary for their support. 
Cockles are in great request as food among the labour- 
ing classes, and are caught for this purpose chiefly in the 
winter months. Their size is various, from five or six 
inches to half an inch in diameter. The shell is somewhat 
heart-shaped, with twenty-six longitudinal ridges, and 
transversely wrinkled, somewhat imbricated striae ; the 
colour pale, or whitish. 
