THE CRAYFISH AND OTHER CRUSTACEA 89 



Crayfishes are very widely distributed over the United 

 States and occur also in many parts of the old world. 

 There are many different species. Some of them inhabit 

 ponds and streams; others are found in damp soil where 

 they dig holes often to a depth of several feet. Some of 

 the burrowing species heap up the dirt which is brought 

 up in digging, so that it forms a tube or " chimney" over 

 the hole. One species of crayfish which is found in Mam- 

 moth Cave, Kentucky, is blind; the eye-stalks remain, 

 but the eyes have disappeared. As a rule crayfish are 

 retiring in their habits and usually lodge under stones or 

 in other dark and protected situations, although curiously 

 enough they may be attracted by a strong light at night. 

 Boys often catch them by letting down into the water a 

 string with a piece of meat tied on one end. The crayfish 

 siezes the meat and it does not occur to it to let go before 

 being pulled out of the water. 



The breeding season varies greatly in different species. 

 The young after they are hatched have a strong instinct 

 to cling with their chelae to any object within reach, 

 and for some time hang tenaciously on to the swimmerets 

 of their mother. After a while the young leave their 

 parent and shift for themselves. Like young grasshop- 

 pers, they shed their skin several times before reaching 

 maturity. In the process of molting the skin splits be- 

 tween the thorax and abdomen and the crayfish slowly 

 pulls its body and legs out of the old cases. Even the 

 lining of the stomach and part of the intestine are shed 

 also. Molting is a trying process for crustaceans in gen- 

 eral and some die as the result of the ordeal. As the new 

 skin is very soft the crayfish is not well able to protect 

 itself and usually retires to some sheltered spot. Its usual 

 pugnacity disappears as if it recognized its helpless plight. 

 As the crayfish approaches its full size molting occurs much 



