170 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 



fundamental features at least, the structural condition of the animal's 

 ancestors. Naturalists believe that all backboned or vertebrate 



FIG. 36. Stages in the development of the prawn, Penens potlmirium. A 

 Nauplius larva; B, first zoea stage; C, second zoe'a stage. (From Jordan and 

 Kellogg, after Fritz Miillcr.) 



FIG. 37. Later stages in the development of the prawn, Peneus potimirium. 

 D, Mysis stage; E, adult stage. (From Jordan and Kellogg.) 



