304 PHYSIOLOGICAL SERIES. 



Iwried in the deep cleft of the " Sylvian fissure " that it 

 cannot be satisfactorily seen. These regions of the brain 

 show a considerable resemblance to the corresponding parts 

 of the Tapir's brain. 



The extension downward (ventrally) and forward of that 

 part of the hemisphere which lies behind the tuberculum 

 olfactorium gives rise to a great ventral boss distantly 

 resembling the temporal lobe of the human brain (figs. 173 

 & 174). This is separated from the anterior parts of the 

 hemisphere by a great gulf, which may for convenience be 

 termed the " Sylvian fissure." This is extraordinarily deep, 

 and consists of a deep vallecula extending upward and 

 backward for a considerable distance *. The sulcus which 



Fig. 175. 



OLF.BULB. 



probably represents the " Sylvian fissure " of other Ungu- 

 lates is placed in this deep vallecula. [In this specimen 

 the surface of the brain is in an excellent state of preser- 

 vation, but the areas buried in the pseudosylvian sulcus 

 are soft and utterly destroyed. It is thus impossible to 

 accurately interpret this region. And the only existing 

 accounts do not help us in this matter.] 



The orbital (presylvian) sulcus is placed chiefly upon the 

 ventral surface, and appears, at least on the left side, to 

 open into the clearly-defined rhinal fissure. 



Bearing in mind the exceedingly irregular manner in 

 which such stable sulci as the suprasylvian, postsylvian, 



* In this respect it differs most markedly from the condition represented 

 by Krueg and Flatau and Jacobsohn. 



