154 Journal of Comparative Neurology 



form. On the roof of the prosencephalon in amphibians 

 there are five parts: three dome-like vesicular projections, and 

 two stalked epiphyses. The anterior member (e) may every- 

 where be recognized with certainty as pertaining to the cere- 

 brum. In front it connects with the lobus olfactorius impar 

 and posteriorly is bounded by the velum transversum, immed- 

 iately in front of which arises the first stalked projection or 

 paraphysis {fp x ). The second division (/>) corresponds to the 

 parencephalon which, as in the sturgeon, extends from the vel- 

 um to the supra-commissure. Behind the latter is the fourth 

 member, the pineal {ep 2 ). Thus far there is a complete simil- 

 arity to the sturgeon. But now instead of the post-commis- 

 sure a fifth division appears, an arched segment (d) behind 

 which lies the post-commissure. The author regards this as 

 homodynamous with the first and third portions, and calls it 

 ' Schalthirn Diencephalon.' It is therefore impossible to assume 

 two homodynamous segments, each with a pallium, a stalked 

 epiphysis and a commissure. Perhaps some organs have disap- 

 peared in the phylogenetic development. 



Charles Hill (j./-'qi) describes two epiphyses in the em- 

 bryo of white-fish, one behind, strangulated cross-wise so as to 

 give the impression of a double pineal situated on a single stalk, 

 and the other in front, making its appearance two days later, 

 whose place of origin is plainly removed from the post-plexus. 

 The pre-plexus lies close to the post-commissure in front ; it cor- 

 responds therefore to the well-known pineal in bony fishes. 

 Kupffer was inclined to consider the front plexus as the para- 

 physis but Hill says explicitly that it lies behind the fold, which 

 the wall of the prosencephalon gives off, hence behind the por- 

 tion designated by him as velum transversum. 



Susanna Gage (^-'93) studied the epiphysis and paraphy- 

 sis of Diemyctylus and writes : The epiphysis of Diemyctylus 

 like that of other urodeles is insignificant. In embryos it is 

 prominent, in the early stages a remnant of its connection with 

 the brain remains occuring as usual between the supra- and post- 

 commissures. In the adult this connection has disappeared and 

 its cavity is nearly obliterated. From its caudal end a few 



