NERVOUS SYSTEM. VERTEBRATA. \ \:\ 



Gorilla is shown by the other six hemispheres, in all of 

 which the superior limiting sulcus is separated by an 

 exposed gyrus from the anterior limiting sulcus ; and 

 neither sulcus possesses a markedly opercular lip. In six 

 out o the eight hemispheres the mesial end of the fronto- 

 orbital sulcus appears to join the stem of the Sylvian 

 fissure ; in the other brain the orbital region is damaged, 

 but probably its fronto-orbital snlci were always separated 

 from the Sylvian. 



Fig. 250. (xf.) 



SUL'C, OLTv- 



.'SULC.OCC.7CMP 



SUTC-.PAR.OCC- 



In contrast to the conditions found in the human brain, 

 it is noteworthy that the fronto-orbital sulcus is very long. 



The orbital sulcus is seen on the right hemisphere in its 

 primitive state as a long, deep, simple linear sulcus. It 

 pursues a course parallel to the fronto-orbital sulcus. To 

 its mesial side there is an unimportant secondary orbital 

 sulcus, which is joined to the main sulcus on the left hemi- 

 sphere, to form a triradiate sulcus such as is often found in 

 the human brain. If a large series of human brains be 

 examined (because this sulcus is exceedingly variable), it 



