INSECTA. 85 



animal in recognizing its food.* They cast their shells 

 often during life, and as often renew them. Most of the 

 Crustacea live in the water and feed upon flesh. They 

 are divided into two families, first, those which have the 

 body provided with regular limbs, and covered with a 

 hard shell, as the crabs; and, secondly, those of which 

 the exterior envelope is less solid than that of the testa- 

 ceous tribes, and which, bearing more resemblance to the 

 mollusca, are therefore termed Molluscous Insects. 



FIRST ORDER. 

 BRACHYURA, OR CRABS. 



The River Crab (astacus fluviatilis) is about four 

 inches long, and one inch in thickness ; of a brownish- 

 green color ; has a broad tail ; the first pair of legs are 

 large pincers or claws ; the true legs are situated directly 

 behind these, and arranged for locomotion. Crabs are 

 found in all the brooks of Europe, and are sometimes 

 kept in troughs filled daily with fresh water, but, not- 

 withstanding this care, do not live long ; however, envel- 

 oped in nettles, they bear transportation. They crawl 

 about constantly, both by day and night, in the water ; 

 and in the cold season creep into holes on the banks. 

 Crabs feed on snails, frogs, and dead fish ; but when out 

 of the water they will eat fruit elder berries for instance 

 milk and bran ; in winter and spring they are easily 

 taken in the holes to which they have retired in the cold 

 season ; in the summer from under the stones where they 



* Some naturalists recognize six pairs of jaws ; the first pair are 

 called maadibles, the two next are jaws, properly so called, and the 

 three last arc termed foot-jaws. Tr, 



