INTRODUCTION i- 



waning importance of the tail. In any event, the old-world monkeys do not 

 develop prehensile functions ni their tails, and many of them, like the baboons, 

 have ventured out of the trees to hve more upon the ground. Most of the 

 kxtter show a distinct dog-hkc dc\'elopment in mode of hfe, in size and in 

 form of body. In the gibbons for the first time is estabhshed the abihty to 

 walk upright, but with these animals forest life is still predominant in its 

 inlluence. By means of their long arms they are capable ot swinging from 

 branch to branch with a marvelous agility. The absence of the tail in them, 

 and the partial assumption of the erect posture, are most significant as fore- 

 runners of developments in the larger anthropoids. In these latter a great 

 increase of weight enforced the habit of living nearer to the ground. 



The first of these large anthropoids, the orang-outang, still shows its 

 ancestral adherence to the forest, although it is able at times to stand and 

 run. The chimpanzee, while it has great cleverness in climbing, seeks the 

 ground oftener and has learned to walk upon all fours, using the knuckles of 

 the hand as a support in this act. Finally, the gorilla, often attaining the 

 great weight of nearly four hundred pounds in adult life, has been compelled 

 by this reason to seek the support of the earth and only at times makes use 

 of the heavier portions of the trees for refuge or retreat. Still, so indomitable 

 is the arboreal tendency', even in these great animals, that they have made 

 but imperfect terrestrial adaptation and also at the same time they are onlv 

 partially suited to tree life. Were it not for their prodigious strength, their 

 limited arboreal activities would be even further curtailed. 



All of the man-like apes are capable of the upright posture, of standing 

 and walking on the hind legs but in an awkward, inefTicient manner. This is 

 due to the fact that the foot in all three of these animals maintains predomi- 

 nant characters of the hand and affords at best an imperfect basis for bipedal 

 locomotion. Yet, notwithstanding such limitations as long, dragging arms and 

 inadequate feet, the great anthropoids are able to venture beyond the limit 



