160 Journal of Comparative Neurology 



horizontal section takes its origin from the roof immediately 

 caudad of the supra-commissure. It is not highly developed in 

 any of the Amphibia and in Menopoma lies as a vesicle over 

 the roof between the post- and supra-commissures (Fig. I, 

 Plate XV). 



The paraphysis is not differentiated into a plicated plexus 

 and dorsal sac as in the Reptilia, but forms a nearly solid vascular 

 mass by the intricate foldings and plications of the entire roof 

 of the diencephalon cephalad of the supra-commissure. A large 

 blood sinus is seen entering the plexiform structure from the 

 lateral ventricle. 



In Amblystoma (Fig. 3, Plate XV) we find essentially the 

 same structures as in Menopoma. The epiphysis takes the 

 form of a vesicle, which, though not shown in the figure takes 

 its origin from the roof caudad of the supra-commissure. The 

 plexus is also, as in Menopoma, an intricately folded mass from 

 which a blood vessel is seen to emerge and pierce the skull 

 above. Eycleshymer (p. 40 1 ) describes the ontogeny of the 

 paraphysis and epiphysis in Amblystoma and speaks of a "much 

 elongated paraphysis with lateral diverticles at its distal end 

 arising from the posterior portion of the roof the prosenceph- 

 alqn." He further states that Leydig suggested the term " an- 

 terior epiphysis" for the pararphysis. I have not had access to 

 other sections than the one figured in Plate XV, Fig. 3, but 

 that leads me to conclude that if diverticles, one or more, ap- 

 pear in the early development of Amblystoma they are transi- 

 tory and should never be confounded with the epiphysial struc- 

 ture which is uniform throughout the vertebrates with one ex- 

 ception (Alligator, this paper). For further remarks on the 

 so-called " second epiphysial outgrowth " seethe discussion of 

 the roof of the diencephalon. 



Fig. 4, Plate XV, shows the connection of the epiphysial 

 vesicle with the roof of the diencephalon also the open commu- 

 nication with the third ventricle. The vesicles in front are see- 



the pages refer to our Historical Account, this Journal, April, 1894. 



