72 



COMPARATIVE ANATOMY 



,NP 



Fig. 46— AMPHIOXUS. 



Transverse sections of embryos at successively later 



FIG. 40.— Aivirni^^w^. ^'^f'^^^®^^!'^^?-' ^. „,p,oderm A. section somewhat 



stages, showing origin of notochord Tan embryo sli^UoS^^^ than that represented 



NP nlurSV^te-, NT, neural tube. (After Cerfontame.) 



