728 MAMMALIA. 



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 

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

 ventrally. There are no ischial callosities. They are arboreal in their 

 habits, and make nests in the branches. They are exclusively vege- 

 tarian. As regards the structure of the Israin, 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^ feet 

 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 of 

 their feet on the ground. The skull is not prolonged into a vertical 

 crest. 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 dorso-lumbar vertebra;. There 

 is no OS centrale in the carpus. There are no ischial callosities. They 

 live in families in the forest, and feed on fruits. As regards size, 

 the gorillas are most like man. The males are much larger than the 

 females. 



The Chimpanzees (Anthropopithecns) live in Western and Central 

 Equatorial Africa. They do not exceed a height of 5 feet. The arms 

 reach a little below the knee. They walk on the backs of their closed 

 hands and on their soles or closed toes. The skull has no high crests. 

 The supra-orbital ridges are distinct. The canines are smaller than in 

 Gorilla or Orang. There is no centrale in the carpus. There are no 

 ischial callosities. The chimpanzees live in families in the forest, and 

 are chiefly arboreal, making nests in trees. They seem to feed on fruits. 

 In the sigmoid curvature of the vertebral column the chimpanzees are 

 most like man. 



Family 5. Hominid.'e. Genus Homo. 



The distinctiveness of man from his nearest allies de- 

 pends on his power of building up ideas and of guiding 

 his conduct by ideals. But there are some structural 

 peculiarities of interest. 



Man alone, after his infancy is past, walks thoroughly 

 erect. Though his head is weighted by a heavy brain, it 

 does not droop forwards. With his upright attitude, the 

 increased command of vocal mechanism is perhaps in' part 

 connected. 



Man plants the soles of his feet flat on the ground ; the 

 great toes are often longer, nexer shorter than the others 

 and lie in a line with them ; he has a better heel than 

 monkeys have. No emphasis can be laid on the old dis- 

 tinction which separated two-handed men (Biinana) from 



