ARTHROPODS. CLASS CRUSTACEA 101 
or in the mouths of the burrows which they excavate, and 
from which they rush upon the small fish, the larve of 
many animals, and other equally defenseless creatures 
which constitute their bill of fare. In turn they are 
eagerly sought by certain birds and four-footed animals, and, 
especially in France, 
are extensively used for 
food by man. 
Closely related to 
the crayfishes and dif- 
fering but little from 
them structurally are 
the lobsters. In this 
country they are con- 
fined to the rocky coasts 
from New Jersey to 
Labrador, living upon 
fish, fresh or otherwise, 
various invertebrates, 
and occasionally  sea- 
weeds. Far more than 
the crayfish, the lobster 
is in demand as an arti- 
cle of food. By the aid : 
of nets or various traps Fig. 59.—The crayfish (Astacus). 
