Fish, Brain of the Fur Seal. 73 



insular fissure although the presence of a subgyre and subfis- 

 sure (postica ?) in the caudal wall of the Sylvian might super- 

 ficially indicate it. 



The supersylvian fissure forms a complete arch around the 

 Sylvian. There is no indication of a separation of a postsuper- 

 sylvian except near the free end of the Sylvian where a branch 

 from the supersylvian extends into the adjacent gyre. 



The lateral fissure forms a curve approximately parallel 

 with the supersylvian. As compared with PJioca and CallorJiimis 

 it is much shorter. If the conception of the ectolateral is cor- 

 rect, the latter is continuous caudally with the lateral, a slight 

 spur indicating the place of probable separation. The ectolat- 

 eral extends parallel with the postsupersylvian but its ventral end 

 does not reach so far in Ursiis ainericamis, while in the Thibet 

 bear the reverse is the case. 



The ansate fissure is a cephalo-ventral continuation of the 

 lateral, a small spur of the latter indicating a point of separa- 

 tion. The ansate describes a curve, the convexity pointing 

 toward the Sylvian. 



The coronal fissure continues from the ansate and ends 

 freely near the superorbital. The convexity of its curve like 

 that of the ansate points toward the Sylvian. The point of its 

 separation from the ansate is indicated by a spur more marked 

 than that between the ansate and the lateral. 



The superorbital, unlike Plioca and CallorJdniis, has a very 

 distinct connection with the rhinal fissure at about half of the 

 distance from the Sylvian fissure to the olfactory bulb. It curves 

 cephalo-dorsad with its convexity pointing cephalad. 



The cruciate fissure is more highly developed than in either 

 of the seals. It appears slightly upon the mesal aspect and ex- 

 tends obliquely cephalo-laterad on the dorsal surface. Around 

 its free end the coronal fissure demarcates a well-formed sigmoid 

 gyre. The appearances found in PJioca approximate the condi- 

 tions regarding the gyre more than in Callorhinus. 



Between the cruciate and ansate lies the postcruciate fis- 

 sure. On the left hemicerebrum it is well marked, on the right 

 it is smaller and superficially connected \\'ith a minor fissure, 



