Nn'CETES SENICULUS 



205 



as appears in the more advanced primates, the inception of this fissure is seen 

 in the occipital lobe. The central fissure extends from the vertex of the 

 hemisphere downward and forward toward the main Sylvian fissure in the 



K "^ ' \ 



FIG. 112. BASE OF BRAIN, MYCETES SENICULUS. 



[Actual Length, 46 mm.] 



Key to Diagram, obln.. Oblongata. 



region between the parietal and frontal areas. Its angulation with the 

 superior longitudinal sinus is something less than go°. Lilcewise, the angle of 

 the Sylvian sulcus with the base line of the brain is a little less than 45°, 

 showing a general disposition on the part of this fissure to depart from its 

 primitive vertical position and incline itself more toward the horizontal. 



LOBATION OF MYCETES BRAIN 



The lobation in the mycetes' brain is much more distinct than in the 

 primates below it. This is due to the fact that the major sulci are all well 

 defined. A short fissure indicates the position of the precentral sulcus in the 

 frontal area, and deep fissures situated well forward toward the orbital sur- 

 face indicate the positions of the sulcus prccentralis inferior and the sulcus 



