162 



ANIMAL BIOLOGY 



Among the relatives of the crayfish that live in damp places on 

 land are the pill bug and the sow bug (Fig. 115) which are often 

 found beneath water-soaked wood. All the 

 animals we have described in this chapter 

 belong to the class Crustacea, so-called from 

 the hard outer shell which invests them. 



118. Economic importance of the Crus- 

 tacea. Crayfishes in Europe, particularly 

 in France, are highly esteemed as food, 

 and special efforts are made to increase 

 their number. In this country, however, 

 they have, as yet, been used but little as 

 food. Their principal use is for bait 

 S W in catchin S certain kinds of fish. 



The lobster is to us what the crayfish 

 is to Europeans. While they are not abundant enough to 

 be considered a very important source of food, still the 

 fishermen in 1901 received $1,400,000 for the lobsters 



FlG ' 



FIG. 116. The shrimp. 



caught. They are considered rather as a delicacy, since 

 they are too expensive for general use, principally on 

 account of their scarcity. For a number of years the 

 United States government has been making efforts to 

 increase the number of lobsters by artificial propagation. 

 Some states have passed laws forbidding the catching of 

 immature lobsters and lobsters with eggs attached. 



