THE CRAYFISH. 133 



The next two pair are called the maxillae, although, in 

 fact, these members do not serve in crushing the food. 

 They are hairy joints, and are used to hold the food 

 against the mouth during mastication. 



The last three pair of peribuccal (surrounding the 

 mouth) limbs are called the jaw feet ; they indeed look 

 like feet, but they are kept folded before the mouth, and 

 their use, like that of the maxillae, is to hold the food. 



The thorax of the crayfish is formed of segments 

 which above are united in one large carapace, and below 

 carry five pair of articulated feet, more or less lengthy 

 and hairy; these are the ambulatory feet, for they are 

 used in walking. Their number, in the natural group to 

 which belong the crayfish, the lobster, and the crab, is 

 five pair, and the name Decapods has been given to these 

 animals. 



In the crayfish, the lobster, and the crab the first pair 

 of ambulatory feet are curiously modified. They are 

 terminated by a sort of hand formed like a large pair of 

 pincers ; the interior edges of the blades of these strong 

 pincers are studded with rounded tubercles. The organ 

 thus serves more than its primary purpose, and is useful 

 for prehension. It is called the claw, 



The segments of the abdomen are quite distinct and 

 movable one on the other. On the under surface they 

 have small feet, but very little developed, and called 

 false feet, between which the female carries her eggs 

 after they have been laid. The abdomen is terminated 

 by a number of joints spread out like a fan, and forming 

 the tail. 



The carapace of the crayfish is hard, but the animal, 

 like many other crustaceans, sheds its coat at cer- 

 tain seasons, that is, it abandons its carapace, out of 



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