74 Descriptive Zoology. 



swimmerets. The eggs are small and smooth, reddish or 

 dark, and in the mass suggest the appearance of a berry ; 

 hence the mass of eggs is called the " berry." A lobster 

 with the eggs attached is called a "berry lobster." From 

 the eggs hatch the little crayfishes, which have the form of 

 the adult. These little fellows have incurved hooks on the 

 ends of their claws, by means of which they take fast hold 

 of the swimmerets of the mother and remain so attached 

 for some time. 



Rate of Growth of Crayfishes. The crayfish is about a 

 quarter of an inch long when hatched. At the end of the 

 first year it is about an inch and a half long. After the 

 first year it grows more slowly, and seldom becomes more 

 than five or six inches in length. 



Molting. Since the hard parts are on the outside, 

 such creatures would soon reach a limit of growth unless 

 some special provision were made. This is provided for 

 by the shedding of the entire outer hard covering at stated 

 periods. The hard shell splits across the dorsal surface 

 at the junction of the cephalothorax and abdomen. The 

 carapace also usually splits part way forward from the 

 transverse opening above mentioned. By severe effort 

 the cephalothorax and its appendages are first extracted ; 

 then the abdomen is pulled out of its hard covering. This 

 is a critical period in the life of the crayfish. Sometimes 

 the big pinchers are broken off in the effort to get them 

 out of the old case. Crayfishes sometimes perish in the 

 struggle to get free from their " hide-bound" condition. 

 And for some time after molting the body is soft, and 

 hence almost defenseless. At this time the animal is un- 

 usually timid, and lives in hiding till its skin again hardens 

 by the addition of limy matter. After shedding, the cray- 

 fish is doubly helpless; not only is his body soft and easily 



