790 



MAMMALIA. 



young birds, spiders, and insects. Their voice is powerful, and one 

 species (the Siamang) has a laryngeal sac. As regards teeth, the 

 gibbons 'are most like man. Some authorities rank the gibbons in a 

 separate family apart from the three other Anthropoids. 



The Orangs (Simla} live in swampy forests in Sumatra and Borneo. 

 The males measure over 4 ft. They walk on their knuckles and 

 on the outer edges of the feet. The skull is prolonged into a vertical 

 crest. There are but slight supra-orbital ridges. The canines are very 

 large. There are twelve ribs as in man, and sixteen dorso-lumbar 



FIG. 419. Skull of gorilla. 



vertebrae. The larynx is connected with two large sacs which unite 

 ventrally. They are arboreal in their habits, and make nests in the 

 branches. They are exclusively vegetarian. As regards the structure 

 of the brain, the Orangs are most like man. 



The Gorillas {Gorilla} live in Western Equatorial Africa. They are 

 larger than all other apes, and larger than man, though not over 5^ ft. 

 in height. The arms reach to the middle of the lower leg, and the 

 animals walk with the backs of their closed hands and the flat soles ol 

 their feet on the ground. There are prominent supra-orbital ridges. 

 The canines of the males are very large. The cervical vertebrae bear 

 very high neural spines, on which are inserted the muscles which 

 support the heavy skull. There are thirteen ribs, and seventeen 



