800 



ME. F. E. BBDDAED OS TSB 



[June 20, 



Behind the optic chiasma is a large somewhat heart-shaped 

 elevation (c, d). It is divided anteriorly by a median furrow which 

 is well-marked and deep ; behind it shows indications of division 

 into two. This elevation appears to me to be the tuber cinereum 

 and the corpora albicantia partly fused, but whose independence 

 is still to be recognized on a careful examination. 



Kg. 2. 



Brain of Hydrochmrtis, ventral view. Nat. size. 



s, pallium ; h, olfactory nerve ; a, origin of same ; c, tuber cinereum ; 

 d, corpora albicantia ; p, pituitary body. 



Other features to be noted on the ventral surface of the brain 

 will be seen by an inspection of the accompanying drawing. 



Fissures of the Hemispheres. 



I shall take as an assumed normal the best preserved of mj' 

 three brains, indicating the divergences in arrangement which the 

 others show. 



The most salient fissure is that lettered a (fig. 1). It runs 

 almost from end to end of the brain ; at about the middle of its 

 course it is bulged out on either side, and on the left side it is just 

 interrupted by a bridging convolution, and is thus divided into two 



