'24 THE HIGHER ANTHROPOIDS 



Coefficients of the Oculomotor Decussation in the Higher Anthropoids 



COMPARISON OF THE GREAT APES AND THE INTERMEDIATE PRIMATES 



Moru inturusting than the comparison ol the great anthropoids among 

 themselves is the contrast atlorcled between them and the intermediate 

 ])nmates. In this, witli the exception ol' the orang-outang, the man-hke apes 

 all sho\\' a pronounced advance. The macacus apparently has a dexclopment 

 in this respect which is equal to that ol tlu' orang-outang; whik' the baboon 

 exceeds the orang and stands next to the chimpanzee in the tli'\ x'lopmcnt of" 

 Its oculomotor decussation. The gibbon occupies the lowest i^lace in this 

 comparison. The high ligurt' re|5rt-sentmg the balloon is undouL)tedl\ due to 

 the laet that this animal, as it li\cs m more exposed places, is m need of 

 rapid \isual adiustmeiit to near and distant obiccts. It is contiiuiall\ on the 

 lookout not only lor the approach ol danger, but in search ol suitable objects 

 lor Its marauding exploits. 



COMPARISON OF THE GREAT APES AND THE LOWER PRIMATES 



\\ hen comparison ol the great anthropoids is mack' with the lower 

 primates, the real strides in the organization ol \Isual lunction beconieappar- 

 ent. In this particular there exists tlu' striking dillercncc between gorilla and 

 lemur ol 72 per cent, between gorilla and marmoset, of jo pvv ci'iit, and e\cn 

 the wily mycctes, with all the additional acKantages of its prehensile tail, is 

 approximately 20 per cent below the great ant hro[)oids. I hese dillerences arc 

 too great to leave doubt concerning the expansion which has alleetcd the 

 progressive de\clopment of coniugated c\ (,■ mo\inunts m t lu' interest ol 

 binocular \Tsion. 



