404 



THE HIGHER ANTHROPOIDS 



prominent and extends from the superior longitudinal sulcus toward the 

 base of the temporal lobe. It separates tlie parietal from the oeeii)ital lnl)e 

 and forms a boundary between tlie oeci|Jital and temporal lobes. The presence 



FIG. 225A. LEl-r LATERAL SURFACE OF BRAIN, ORANG-OUTANG. 



(AcUial L^ngtli q6 nun.] 



of this simian sulcus, so well defined m the orang, adds a feature to the lateral 

 cispeet ol the hemisphere usually not present in the human bram. It thus 

 serves as one oi the distmguishmg marks bt'lween man and the anthropoids. 

 Its developmi'ut in orang has more of the pruiiitive simian character than is 

 the case in either cinmpan/.ee or gorilla. The convolutional pattern ol the 

 parietal lobe, as is always the case, shows the greatest richness ot gyration, 

 and, in accordance with the rule, tlu" ti'inporal lobe is the lU'xt most consjjic- 

 uous in this particular. 1 he superior tem|)oral sulcus, ho\\e\er. Is not contin- 

 uous into the parietal lobe as m the higher [)rimates; a deep annectent gyre 

 interrupts this sulcus near the base of the temporal region so that it is diffi- 

 cult to identify an angular g\ rus. The coiiMilutional pattern in thi' frontal 



