76 THE LIFE OF CRUSTACEA 



The shrimp-like Euphausiacea have a larval 

 development very like that of Penaus. Most, if not 

 all, of the species are hatched from the egg in the 

 nauplius stage, and pass through stages very similar 

 to those described above. The adult animals, how- 

 ever, may be said to remain in the " schizopod " 



FIG. 30 NEWLY-HATCHED YOUNG OF A CRAYFISH (Astaciis 

 fluviatilis). ENLARGED 



stage, since the exopodites of the thoracic legs remain 

 large and are used in swimming. 



Even among the Decapoda, however, there are 

 many species that are hatched from the egg in a form 

 that does not differ essentially from the adult, and 

 are therefore said to have a direct development. 

 This is often the case with species which live in 

 fresh water or in the depths of the sea. For 

 example, the young of the fresh-water Crayfish 



