TROGLODYTES GORILLA 



647 



structure often denominated the interorbital keel of the frontal lobe has lost 

 nuuh of its jjrominence and approaches more closely the conditions observed 

 in man. The entire orbital surface of the frontal lobe has in fact so altered its 



FIG. 292B. DETAILED DIAGKA.M OF DORSAL SURFACE OF BRAIN, GORILLA. 

 Key to Diacr.\m. inc. s. cin., Incisura Sulci Cinguli; sllc. occip.. Sulcus Occipitalis; s. fr. sup., Sulcus 

 Frontalis Superior; sllc. prec. slp.. Sulcus Prcccntralis Superior; sllc. ret. slp.. Sulcus Rctroccntralis 

 Superior. 



external configuration as, for the most part, to present a tendency toward 

 conve.xitv and is thus nearly devoid of the marked indenture so characteristic 



