QUADRUMANA. 



557 



In this tribe are the Gibbons (Hylobates}, the Orang-outang 

 (Simla satyrus), the Chimpanzee, and the Gorilla. 



The Gibbons form the genus Hylobates, and they belong to 

 southern Asia, and the Indian Archipelago. The anterior limbs 

 are extremely long, and the hands nearly or quite reach the 

 ground when the animal stands in an erect posture. There is 

 no tail, but there are natal callosities. The body is covered 

 with a thick fur. One of the best known of the Gibbons is 

 the Siamang (Hylobates syndactylus], which has been sometimes 

 regarded as making a nearer approach to man than any other 

 of the Monkeys. It is a native of Sumatra. 



In the Orang (Simla satyrus) there are neither cheek- 

 pouches nor natal callosities, and the hips are covered with 

 hair. As in the Gibbons, the arms are excessively long, reach- 

 ing considerably below the knee when the animal stands in an 

 erect posture. The hind-legs are very short, and there is no 

 tail. When young, the head of the Orang is not very differ- 



Fig. 212. A, Skull of the Orang-outang. B, Skull of an adult European. 



ent from that of an average European child; but, as the animal 

 grows, the facial bones become gradually produced, whilst the 

 cranium remains in a tolerably stationary condition ; great bony 

 ridges are developed for the attachment of the muscles of the 

 jaws and face; the incisors project; and ultimately the muzzle 

 becomes as pronounced and well-marked a feature as in the 

 typical Carnivora (fig. 212, A). The Orangs are all inhabi- 

 tants of Sumatra, Borneo, and the other larger islands of the 

 Indian Archipelago. 



The genus Troglodytes contains the Chimpanzee (T. niger) 

 and the Gorilla (T. Gorilla). The Chimpanzee is a native of 



