CRUSTACEA 99 



The protective resemblance is excellent, the colors varying from 

 a delicate pink or tan to a dark green or purple. 



Use. — Crayfishes are used by the million in France, and to a 

 limited extent in the United States, for food. They also furnish 

 food for fishes. Raccoons, muskrats, and crows prey upon 

 them. 



The lobster (Fig. 72) is marine and is very much like the 

 crayfish, only much larger. Specimens weighing twenty-five 



Fig. 72, — A small lobster (dorsal view) mounted on a glass so as to show 

 both dorsal and ventral views. Students' work. 



pounds have been captured. Among the invertebrates the 

 lobster ranks next to the oyster as an article of food for man. 



Prawns and shrimps look like our common crayfish and are 

 used to some extent for food. They are small. The common 

 prawn {Palcemone'tes vulga'ris) is about 2 inches long. It is 

 transparent, so that the viscera can be seen through the thin 

 leathery carapace. 



