304 



C. O. WHITMAN. 



as a precocious appearance of a character which originated in 

 the differentiation of the two hemispheres of the primordial 

 Blastula, and the concentric segregation as a peculiarity inherited 

 from the Archicjastrula. 



f. 



Figs. 1, 4, and 9 = Clepsine. 



Fig. 2 = Pristiurus (after His). 



g. b. = Germ-band, 



p. gr. = Primitive 

 groove. 



Figs- 3 and = Chick (after llanbcr). c. I. = Caudal lobes. 



Fig. 5 = iSalmo (after His). R. = Anus of Kusconi. 



Fig. 7= Accipenser (after Kowalevsky). w. «.= Marginal notch. 



Fig. 8 = Frog (after Rusconi). p. = Entoplasts. 



