TROGLODYTES GORILLA 



651 



first, the expansion of the occipital region of the hemispheres in the interest 

 of further enriching the visual fields and thus visual association; second, by 

 a conspicuous expansion in the lateral lobes of the cerebellum. The decrease 



FIG. 294B. DETAILED DIAGRAM OF LEFT HEMISPHERE OF BRAIX, GORILL.\. 

 Key to Diagr.\m. sllc. fr. sup.. Sulcus Frontalis Superior; sllc occip. lat.. Sulcus Occipitalis Lateralis; 

 SULC PR. INF., Sulcus Precentralis Inferior; SLXC PR. sup.. Sulcus Precentralis Superior; SULC ret. inf.. 

 Sulcus Retrocentralis Inferior; suLC sub. post.. Sulcus Subcentralis Posterior; suLC te-MP. med.. Sulcus 

 Temptoralis Medius. 



in the cerebellar concavity is shown particularly on the lateral aspect of the 

 under surface. In but one region does this indenture bear any of its original 

 prominence as seen in the lower primates. This is at a point near the midline 

 just caudal to the splenium of the corpus callosum where a vestige of the 

 former deep concavity is still apparent, the postsplenial fossa. In the main, 

 the basal surface of the occipital lobe is assuming a tendency toward con- 

 vexity and is rounding out its convolutions in such a manner that they pass 



