1 62 Journal of Comparative Neurology 



optic vesicle. His statement (p. 29) that "from the structure of 

 the epiphysis of adults it can be determined with certainty 

 whether a portion has been constricted off or not ; in the former 

 case it bends forward and ends in a point, in the latter it is 

 fungiform," is an interesting one and should be kept in mind by 

 all who are working in this most interesting field. Our drawing 

 of Phrynosoma coronata {Jour. Comp. Ncitr., Vol. Ill, PL 

 XII, Figs. 1-2) would hardly agree with this statement while 

 those of Sceloporus striatum do (Plate XVI, Fig. 5). 



Fig. 8, Plate XV, is an imperfect section of the roof of 

 the diencephalon and shows a .stage in the development of the 

 epiphysis. Although the structures are imperfect they are suf- 

 ficiently intact to show that the epiphysis may assume different 

 transitory forms in its development. In this case it seems to 

 have a glandular structure. 



If the above specimens are fair representatives of amphi- 

 bians, we would say that in general the epiphysis is relatively 

 smaller than in fishes, while the paraphysis, on the other hand, 

 is far more complex. As to the relative position and number 

 of the structures forming the roof of the diencephalon no vari- 

 ation from those of the fishes occurs. 



We now come to the group most interesting in the study 

 of the much mooted parietal eye. We are at one struck with 

 the strange modifications of the diencephalic roof and yet re- 

 cognize that even here, we have the same parts, structures and re- 

 lations only with modified forms. In our historical resum'e 

 which preceded this article we found no exception to the reiter- 

 ated statement that the epiphysis (pineal) is found in all craniate 

 vertebrates. We propose, however, to state now after a careful 

 examination of three different series of sections in all of which 

 the parts of the roof were perfectly preserved, that we have 

 found one notable exception. Figs. 1-3, Plate XVIII, are 

 exact drawings of perpendicular and transverse sections of what 

 is found to constitute the roof of the diencephalon in the Alli- 

 gator. It is very evident from the perpendicular section (Fig. 

 2) that the epiphysis is entirely wanting, the post- and supra - 

 commissures being intimately connected by an exceedingly short 



