NERVOUS SYSTKM. YKUTKIJUATA. 



transverse occipital sulcus which (as the right side, in 

 which the operculum has been cut away, shows) does not 

 exactly coincide with the bottom of the Simian . 

 ("Affenspalte"). 



A comparison of the dissected and the undissected hulvi-s 

 of this specimen shows how extensive an operculum is 

 present, and how complete the Simian sulcus is in this 

 Chimpanzee. In marked contrast to the condition found 

 in the Gorilla, the dorsal part of the parieto-occipital sulcus 

 is altogether covered by the operculum (see the right 

 side). 



Fig. 251. (xf.) 



StlLC.SIM. 



^^i^P 



i. SULC. TRANS. OCC 



SOLC. PAR. OCi 



The parallel sulcus is partially hooked around the bifid 

 extremity of the Sylvian fissure on the right side, but not 

 so completely on the left hemisphere. 



The posterior element of the inferior temporal sulcus is 

 prolonged backward into a very deep sulcus skirting the 

 ventral border of the occipital region. A similar disposition 

 is found in the Gorilla. 



The area lying behind the " Affenspalte " seems to be 

 much poorer in sulci than is that of the Gorilla. The 

 lateral occipital sulcus has lost the typical Y-sbape, and i" 

 an irregularly arcuate shallow sulcus. 



