280 EMBRYOLOGY OF THE LOWER VERTEBRATES CH. 



fiTteSi 



Sift 



h 



Islll 



BgJ 

 P *Ji 



F ^.f - T 



- = - = 



I2&|| 



0*5 I 



^ Icv-'= 

 5 S^.= M 

 i 3 J a 5 B 



2 5 - = s = 



r- ~ - is '= = 

 ^ =:c:H-_ 



i |i|r 



. = tt- 



e 1 



SBml 





= 0- 



1: 



Sit 



M 



