1 8 Journal of Comparative Neurology. 



superficially makes it apparently extend over two centimeters. 

 As with the right hemicerebrum a dorsal and a ventral branch 

 are given off on the mesal surface, near the dorso-mesal margin. 

 The cruciate continues superficially as far as the splenium with 

 a fissure corresponding to the super-callosal. A super-callosal 

 seems to be represented on the right side, but it does not join the 

 cruciate. 



The splenial fissure arises at the dorso-mesal margin of the 

 hemicerebrum at about the level of the splenium. It is oblique 

 in its direction (ventro-caudal) and is more vertical than hori- 

 zontal. It extends well on to the ventral aspect (about one 

 centimeter). 



In the dog and cat cerebrum the fissures are for the most 

 part isolated and distinct ; but in the seal there are numerous 

 branches given off and rather an unusual amount of confluence 

 of the larger fissures. The complexity is increased by the sinu- 

 ous course and the presence, below the surface, of numerous sub- 

 gyres or outgrowths along one wall, while the other wall overlaps 

 and becomes more or less concave in adapting itself to this 

 growth. This sinuosity at the depth of the fissure (much more 

 marked than at the surface) makes an accurate sounding well- 

 nigh impossible. The obliquity of the fissures and the over- 

 lapping of one wall by the other, especially in the case of the 

 ventral portion of the splenial amounts to almost an operculum 

 or poma. These conditions in many regions render the accu- 

 rate determination of a fissural integer very difficult. 



Underlying all there seems to be a fissural pattern not un- 

 like that of the feline to which are added the various complex- 

 ities above enumerated, but these are hardly sufficient to ob- 

 scure the carnivore type. 



