IVORMS, CRAYFISH, CENTIPEDS, ETC. 153 



blood out through the thin walls into the water. Note 

 the pincer-like appendages of the first pair of legs. 

 These are the chelae with which food is torn into bits 

 and placed in the mouth. 



In meadows where water stands for certain seasons of 

 the year there may be noticed many scattered holes with 

 slight elevations of mud about them. These are mostly 

 the burrows of crayfish. During the dry season the ani- 

 mal digs down until it reaches water, or at least a damp 

 place, where it rests until wet weather brings it to the 

 surface once more. One of these burrows followed in the 

 process of digging a mining shaft extended vertically 

 down to a distance of twenty-six feet, where the crayfish 

 was tucked snugly away. 



The eggs are carried by the female on her abdominal 

 appendages. Previous to laying them she rubs off, with 

 the fifth pair of legs, all the dirt from the appendages and 

 smears them with a sticky secretion. When the eggs are 

 laid, which is during the last of March or April in the 

 Central States, they are caught on the sticky pleopods, 

 where they remain attached in clusters. After some 

 weeks the young crayfishes issue from the eggs. In gen- 

 eral appearance they are not very unlike the adults. 

 They grow very rapidly at this stage. As the animal is 

 inclosed in a hard shell, growth can take place only 

 during the period just following the moult, for the 

 crayfish casts its hard shell periodically, and it is 

 while the new shell is forming that it does its growing. 

 When it moults it casts not only the exoskeleton, 

 but also the lining of part of the alimentary canal. 

 After the females have hatched their young many of 

 them die in the shallow pools, in which places the 

 dried-up skeletons are noticeable during the summer 

 months. 



For an exhaustive account of the biology of the cray- 



