CRUSTACEA 



101 



is much broader than that of the crayfish, and the abdomen, 

 which is used only to protect the eggs of the female, is folded 

 under the cephalothorax. They are great scavengers. Many 

 kinds are used as food. One of the best for this purpose is the 



Fig. 74. — Successive stages of the molting of one individual of the blue 

 crab, Calli'nectes sa'pidus. (G. Hay, in Doc. 580, Bureau of Fisheries.) 



edible or " blue crab " {Callinectes sapidus), great numbers 

 of which are caught along the Atlantic and Gulf coasts. 

 They are best liked for food just after their molting (Fig. 

 74), and are then called " soft-shelled crabs." They are 



