STRUCTURAL CULMINATION (),-() 



c'\ icK'iK'c ol rc'spoiisr alonu llirsc lines ami at the same tunc \ iclcls to iiillii- 

 cnces ol specialization w hu'li (li\'ert it into a |)ath ol its own. In the case ol the 

 marmoset, the impulse toward anthro|joKl evointion is more strongly active 

 as a generalized inlluciiee, not \ et specilic enough to ckti'rmine those mdi'lible 

 cerebral characters which aresullicient to distinguish all ol the other lamilies, 

 genera and specK's in tlu' suborder anthro])oidea. 1 hat the lull lorce ol the 

 tendencv toward simian dillen-ntiation is ultimately lelt by all ol the mon- 

 keys ol the new world is clearly attested by tlie lissural patterns ol these 

 primates. The Ccljidae re\t'al what was dclinitelx attempted m the diller- 

 entiation ol the lemur's brain, subject perhaps to some Irustration b\ other 

 inlluenccs, but again somewhat U-ebl\ aimed at in the marmoset's brain. 

 Ail of the new world simians present a lissural pattern which marks them as 

 nu-mbers ol tlu' suborder ant hropoidi'a. The SyKian lissure takes a more 

 oblicpie course backward and upward, separating the parietal Iroin the 

 temporal lobe. 



The central sulcus, which represents tlu' lissure ol Rolando, is now well 

 dclincd and forms the boundary between the trontal and jjarietal lobes. 

 The sulcus ])arallelus i superior tem])oral lissure) is distinct, as arc also the 

 intermediate tt'inporal and the intraparietal hssures. The greatest degree of 

 fissural specialization occurs in the temporal and parietal lobes. Only the 

 slightest indication ol hssures is lound in the Irontal and occijjital regions of 

 the brum. 1 n I act, neither o I these lobt's shows any marked extent ol expansive 

 development, thus no doubt accounting lor the high degree of broad brained- 

 ncss recorded in Mycetes seniculus. In the Irontal region there is a slight 

 indenture indicating the superior Irontal sulcus, and one somewhat more 

 pronounced marking the position of the inferior frontal sulcus. In the occip- 

 ital lobe, which is but slightly developed, there is a faint indication of that 

 remarkable sulcus which identilies all ol the simian tribe, the sulcus simia- 

 rum. This lissure appears in mycetes as well as in other Cebidae as a small 



