72 Journal of Comparative Neurology. 



On the meso-ventral surface a fissure corresponding to the 

 collateral is also present, but, unlike Callorhinus, it has connec- 

 tion with the postrhinal. Between the collateral and the post- 

 splenial there is another well marked but unnamed fissure which 

 is parallel to the former. It corresponds perhaps to the fissure 

 in CallorJiimis which I have spoken of tentatively in connection 

 with the occipital. 



The genualis and rostralis are represented but the latter 

 differs from that in CallorJiimis in being much less developed 

 and occupying a more ventral position at a more or less acute 



angle to the genualis. 



URSUS AMERICANUS. 



This brain, while fairly well preserved, had been consider- 

 ably mutilated in removal, so that for purposes of illustration 

 and reference, a specimen from Ursus thibetianus, kindly loaned 

 by Prof. B. G. Wilder,^ was utilized ; so that while the figures 

 of the lateral and mesal aspects are from the latter specimen, 

 the description is based almost entirely upon the former. The 

 general arrangement of the fissures is similar and the minor de- 

 tails need not cause misapprehension. The fissural plan of the 

 brain is much like that of the canine, minus the first circumsyl- 

 vian arch. 



The olfactory bulbs and crura are far superior in size to 

 those of either of the seals. The olfactory fissure is likewise 

 well marked. 



The rhinal fissure passes into the Sylvian and continues, 

 after forming an angle delimiting a well developed pyriform 

 lobe, as the postrhinal and ending freely. The subfissure 

 (postica ?) in the caudal wall of the Sylvian extends to and, on 

 one side, actually appeared to communicate with the postrhinal. 



Lateral aspect. The Sylvian is directed, in the usual dorso- 

 caudal direction at the bottom of which is a small and simple 

 area representing the insula. There is no appearance of a trans- 



^ Papers, chiefly anatomical, presented at the Portland Meeting of the A. 

 A. A. S., August, 1873, ^""C devoted largely to a description of the brains of 

 Carnivora. 



