ORIGIN AND STRUCTURE OF THE HEAD 



51 



Van WYHE (1882, p. 18), reaching from a point over the 

 optic vesicles to a little distance in Iront of the latter. The 

 dorsal end of this frontal or terminal suture, the angulus 

 terminalis, according to HIS, represents the fore-end of the 

 medullary suture or the dorsal brain axis, its vential 

 -extremity, the recessus infundibuli, the termination of the 



dorsal suture 



Angulus terminal'! 



^anterior end of th< floor after Kui 



after His: frontal Sutu 

 After Kupffer: primary fl 



Anterior end of the floor 



after His. 



notochord. 



Fig, 15. Diagram of the Craniate brain and its main axis 

 from Froriep, 1S94 (Ergebn. Anat. Entw. Hi). 



axis of the medullary plate or the basal brain axis, its 

 middle, about the recessus opticus, the fore-end of the 

 median brain-axis. Thus the brain does not end in a 

 point, as assumed by V. KUPFFER, but in a frontal linear 

 suture running over the middle of the lamina terminalis. 

 The existence of such a suture in front of the recessus 

 neuroporicus or angulus terminalis is, however, denied by 

 V. KUPFFER (1894, p. 102). 



Different situation of the neuropore in Urodelans and 

 Anurans. — Perhaps some observations made by me on the 

 closure of the cerebral plate in Amphibians may contribute 



