158 Journal of Comparative Neurology 



is a long tubular projection from the diencephalic roof and rests 

 upon the slightly folded plexus beneath. Figs. 3 and 4 are 

 transverse sections of a young catfish one inch long, cut through 

 the entire body, wh ich show the epiphysis and also a vesicle 

 lying immediately beneath and in contact with the skull roof. 

 There can be no doubt from the structure and position of this 

 vesicle that it has its origin from the distal end of the epiphysis 

 and is perhaps the rudiment of a primitive optic vesicle, as C. 

 Judson Herrick has observed. 



Plate XIV, Fig. 1, shows a horizontal section of Lophius. 

 The sections were imperfect and only the epiphysis with its re- 

 lation to the roof could be found. 



Figs. 10 and 11, Plate XIV, are transverse sections of the 

 epiphysis of Lucioperca. Its origin from the third ventricle is 

 not shown, but by comparison with other fishes there can be no 

 doubt that the epiphysis is evaginated from the roof of the 

 diencephalon and assumes the usual tubular structure and form. 

 The folded plexus is seen lying immediately below the tube of 

 the epiphysis. 



Fig. 7, Plate XIII, is a perpendicular section of the epi- 

 physis and related parts of the trout (Trutta fario). The epiphysis 

 is well defined and presents the appearance of a vesicle with 

 diverticles from its walls. It arises immediately caudad of the 

 supra-commissure, which consists of two separate bundles, and 

 is still in open communication with the ventricle. The plexus 

 upon which the epiphysis rests has only a single fold presenting 

 a very simple structure. Dorsad of the epiphysis will be seen 

 a bony structure. 



In Hyodon we found the same structures and relations 

 which obtain in Cycleptus as described below. 



Figs. 7-8, Plate XIV, show transverse sections of the 

 epiphysis of Cycleptus elongatus. From its origin caudad of 

 the supra-commissure the epiphysis runs forward over the plex- 

 us, which is slightly folded, through forty sections. It retains 

 its tubular structure and form throughout its entire length. 



The structure of the roof of the diencephalon of Scaphi- 

 rhynchus (Plate XIII, Figs. 5, 6, and 8,) and of Lepidosteus 



