296 



ZOOLOGY 



way of saying that a species is losing ground. Two general methods have been 

 tried to make good the decline in the supply: first, legislation forbidding the taking 

 of animals under the size which indicates sexual maturity (eight to twelve inches), 

 and forbidding the capture of females carrying the developing embryos; and, sec- 



FiG. 133. 



Fig. 133. Palamonetes vulgaris. From Verrill. 



Questions on the figure. — Compare the appendages of Palaemonetes with those 

 of the lobster, the crab and Gammarus. What seem to be the functions of the 

 various appendages, so far as position and form may indicate? 



Pig. 134. 



Fig. 134. Gammarus orttatus. From Verrill. 



Questions on the figure. — How does this form compare with the lobster and 

 the crabs in differentiation of the segments, in fusion of the segments and in the 

 differentiation of the appendages? 



ond, attempts on the part of the national government to hatch artificially and care 

 for the moulting young under such conditions that they will be protected from 

 their natural enemies. The problem is not yet solved, and in the meantime 

 another source of food is likely to be destroyed through overfishing. 



The crayfish is prized for food in European countries, but is little used in 

 America as yet. Shrimps, prawns, the "soft-shelled" or blue crab are all of 

 considerable importance in this regard. The smaller Crustacea are a very im- 

 portant element in the food supply of the fishes, both in the fresh waters and in the 

 sea. 



Class II. Onychophora. — Peripatus is the best known genus of this class. It 

 is interesting chiefly because it is, in some degree, intermediate between the 



