450 



METAZOAN PHYLA 



animals are tailless, all assume a semi-erect position, and all have oppos- 

 able thumbs and great toes. With the exception of the gorilla they are 

 preeminently arboreal. As compared with man the anthropoid apes 

 have stronger jaws and teeth; they have a relatively low cranial capacity; 

 the structure of the mouth is not such as to admit of articulate speech; 

 the arms are long and, together with the scapulas, or shoulder blades, are 

 developed in accordance with their use as organs of locomotion in trees; 



Fig. 346. — Male gorilla, Gorilla gorilla, reared in captivity. Gorillas are the most 

 powerful of all the primates. They are chiefly terrestrial, usually quadrupedal, but able 

 to stand erect. Their skin is black — the only " negro " ape. They inhabit heavily forested 

 country of tropical West Africa; now protected in sanctuary by Belgian government. 

 {Photographed by permission of Zoological Society of Philadelphia, by Hartman, from the 

 Science News Letter, May 20, 1939.) 



the feet as well as the hands are grasping appendages; and they cannot 

 assume a fully erect posture. 



The gibbons, the least manlike of the great apes, are strictly arboreal, 

 whereas the gorillas, regarded as the most manlike in bodily form, are 

 preeminently terrestrial in habit. From this it would appear that there 

 has been a gradual tendency to change from arboreal life to life on the 

 ground. 



A noteworthy characteristic of these apes is the specialization of the 

 two pairs of limbs for entirely different modes of locomotion. The 

 arms, adapted for grasping and for swinging from limb to limb, serve 

 as locomotor organs in the trees, while the legs, though still showing 



