xxvii DEVELOPMENT 347 



the appearance of fresh appendages, in regular order, behind 

 the first three (Fig. 91) ; by the elongation of the rudiment 

 of thorax and abdomen (ab) ; and by the gradual differen- 

 tiation of the appendages. When hatched the young 

 animal agrees in all essential respects with the adult, but its 

 proportions are very different, the cephalothorax being nearly 

 globular and the abdomen small. For some time after 

 hatching the young crayfishes cling in great numbers to the 

 pleopods of the mother by means of the peculiarly hooked 

 chelae of the first pair of legs. 



