CRABS, ETC. 



77 



pairs of jointed organs, fitting closely together, their office 

 being to take the food from the claws and prepare it for the 

 stomach. The first pair are the jaws proper, or mandibles, 



Cephalo-thorax. 



Abdomen. 



FIG. 81. Cray-fish seen from the side, with that portion of the carapace re- 

 moved which covers the branchiae, or gills. The appendages of the left 

 side only shown, s, region of stomach ; A, abdominal appendages ; B, 

 bases of the four small legs ; C, base of large claw ; f, " gill-bailer," or 

 flabellum, attached to the second maxilliped ; <?, eye. (After Morse.) 



that cut and grind the food ; the -next two pairs, i and 2, 

 are assistant jaws, or maxillce. Below these are three pairs 

 of appendages called foot- jaws, or maxillipedes. These be- 

 long to the thorax, while the mandibles and pairs of max- 

 illa belong to the head proper. The segments of the ab- 

 domen fit loosely together, so that the " tail " can be bent 

 beneath the body, and by flapping it vigorously the cray- 

 fish swims, the five flattened appendages (Fig. 82) at the 

 end serving as fins. From the under portion of the cephalo- 

 thorax extend five pairs of legs : the first pair are the large 

 claws prominent in the lobster, where one is a crusher 



