376 



BRANCH CHORDATA 



ground to aid in walking they rest upon the back of the knuckles. Cheek 

 pouches and tail are lacking and the hair is more scanty than in the baboons. 

 These entirely Old World forms have a vermiform appendix. 



The gibbons (Hylob'ates), slender, monkey-like Indo-Malayan forms, 

 stand at the base of the series. They are the smallest and most arboreal 

 and their arms are the longest of any of the group, being long enough 

 to reach the ground even when standing erect. The canines are large in 

 both sexes and the jaws and nose are prolonged. The brain is simpler than 

 in the higher forms. One of the most remarkable habits is their descending 

 flight through the trees, though they never come to the ground. They leap 

 incredible distances, says Hornaday, catch and swing with their hands, catch 

 again with their feet, turning again, and so on, by a series of revolutions 

 almost as fast as the flight of a bird. The largest is the Sumatran Siamang, 

 which stands 3 feet tall and is shining black. The gray gibbons are very- 

 timid, but show strong affection for their young and great courage in their 

 defense. 



Fig. 299. Comparison of skeletons of primates: 1, Gibbon; 2, orang; 3, 

 chimpanzee; 4, gorilla; 5, man. 



The brown orang-utan lives in Borneo and Sumatra, wholly in the 

 tree-tops, coming to the ground only for water. On the ground it moves 

 slowly and swings its body along between its arms like a pair of crutches. 

 In the trees, too heavy for leaping, they swing underneath the branches with 

 their long arms, "grasping a limb with their hook-like hands, and swinging 

 underneath to the next hold, and so on, at great speed." 1 It subsists upon 

 wild fruits, fleshy leaves, and shoots of the screw pine. It is shy and uncer- 

 tain if captured. When young it is easily tamed; when grown, wild and 

 ferocious. Hornaday says "in 1901 the zoological park contained four 

 orangs, all of which were taught to wear clothes, sit in chairs at table, eat 

 with fork and spoon, drink from cups and bottles, and perform many human- 

 like actions without nervousness in the presence of two thousand visitors. 

 Each of the orangs learned its part in about two weeks' training, and at the 



1 Ingersoll. 



