I70 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, Peneus potimirlum. A 

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

 Kellogg, after Fritz M tiller.) 



Fig. 37. — Later stages in the development of the prawn, Peneus potimiriiim. 

 D, Mysis stage; £, adult stage. {From Jordan and Kellogg.) 



