EVIDENCES FROM EMBRYOLOGY 



119 



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

 ancestors. Naturalists believe that all backboned or vertebrate 



Fig. 26. — Stages in the development of the prawn, Pencils potimirium. A 

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

 Kellogg, after Fritz Miiller.) 



Fig. 27. —Later stages in the development of the prawn, Peneus potimirium. 

 Z?, Mysis stage; £, adult stage. {Fro7n Jordan and Kellogg.) 



