Fish, Cerebral Fissnration of the Seal. 17 



dice of subgyrcs at this point makes it very difficult to get ac- 

 curate soundings ; and whether the union of these two fissures 

 is anything more than superficial is therefore somewhat un- 

 certain. 



The lateral fissure is long and tortuous and well on the dor- 

 sal surface ; its average distance from the intercerebral cleft 

 being about one centimeter. On the left side it unites super- 

 ficially with the super-Sylvian at the level of the vertical anter- 

 ior fissure. On the right side the union is deeper and in ad- 

 vance of the anterior. The caudal termination of the lateral 

 fissure is at the extreme end of the crebrum and is in the shape 

 of a T due to the union of a small transverse fissure, possibly 

 the lunate of the cat. 



The ansate is a well developed fissure and is almost directly 

 vertical in its course. It arises within less than a centimeter 

 of the mesal surface caudal to the cruciate and extends ven- 

 trally to about the level of the superficial confluence of the an- 

 terior and Sylvian fissures. On each hemicerebrum there is a 

 superficial union of the super-Sylvian with the ansate but in 

 each there is evidence of a shallow (vadum) between them. 



The diagonal of the cat is not distinctly represented in the 

 seal, unless on account of the very much foreshortened con- 

 dition it has become confused with the ansate or cephalic por- 

 tion of the super-Sylvian. 



The super-orbital fissure arises from the base of the ol- 

 factory bulb, which covers its origin, and extends in an oblique 

 ventro-caudal direction to within one half a centimeter of the 

 basi-Sylvian. 



The olfactory is a very short but deep fissure in which the 

 delicate olfactory crus is almost completely imbedded. 



The cruciate fissure of the right side extends for a distance 

 of a centimeter and a half on the dorso-lateral surface and has 

 considerable depth. It also extends a centimeter and a half on 

 the me.sal surface. Very near the dorso-mesal margin a dorsal 

 branch is given off and nearly opposite this is a ventral branch. 



The left cruciate fissure extends less than one centimeter 

 on the lateral surface, but a minor fissure connecting with it 



