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 



A 



FIG. 36. Stages in the development of the prawn, Peneus potimirium. A 

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

 Kellogg, after Fritz Mutter.') 



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

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



