THE SOFT-SHELLED CLAM. 39 



The habits of the clam are very different from 

 those of the oyster. At first they are very much 

 alike, being tiny, swimming bodies, without shells, 

 and too small to be seen without a strong micro- 

 scope. At length the little oyster settles on an old 

 shell or a stake, turns upon his side, and begins 

 to form a pair of shells, one of which becomes 

 attached to the support. 



This spot is his home, and of his own accord 

 he never leaves it so long as he lives. He has no 

 foot to dig with and no pipe to breathe through; 

 so he lives by opening his shells in the water, and 

 letting it pass over his gills, which gather any 



Figure 14. 



particles of floating food. If an enemy comes, he 

 can close his shells, and that is all that he can do. 

 But with the clam it is very different. His first 

 instinct is to dig a hole and get down out of the way 

 of all his enemies. His little tongue-shaped foot 

 is the organ which he uses as a spade, and in a 

 little while he is safely out of sight. 



