Qucrt. Joiirn. Micr. Sci Fo/. 67, N.S., PL 1 



notoclwrd 



notochjord 



mural plate 

 nxesoder/n 

 endodenn 



fi^-z::^^ cntcron 



txeiu'cd fold 



mLif^al fold 





14 



15 



ixotodxord^ 



ejdoderni 

 tv£^od&i'in 



nvesodsrm- 



,enteron 



