THE EXTERNAL FORM OF ANTHROPOID APES. 45 



the siamang (Hylolates syndaetylus, F. Cuvier).* 

 According to Diard, its arms are not quite so long 

 as those of the wauwau {H. agilis, F. Cuvier). This 

 animal's head is small, with a somewhat retreating 

 forehead, a long, moderately arched crown to the 

 head, and a slightly arched occiput. The base of 

 the nose is depressed, the region of the jaws is only 

 slightly prognathous in the aged male. According 

 to Diard, the eyes are deeply set, the nostrils are 

 very wide, the cheeks fall in below the zygomatic 

 arch, the mouth opens widely, the chin is of in- 

 significant size. It is the only one of the gibbons 

 which possesses the throat-pouch, already described 

 as common to the other forms of anthropoids, and in 

 aged animals it hangs slackly down, almost bare in 

 front. The second and third toes are connected to- 

 gether by a thin web, reaching to the last joint in 

 the male, and to the penultimate joint in the 

 female. The hairs on the forearm turn their points 

 upward, and form a kind of whorl on the wrist. The 

 animal is of a glossy black colour, with a thick and 

 tolerably long coat of hair on the body and limbs. 

 According to Bock, the face is encircled by a grey 

 or white beard. This animal is about a metre in 

 height, and inhabits the woods of Sumatra. 



Tlie lar {Hylolates Lar, Illig) is another species of 

 gibbon. The structure of the body is much more 



* A very good illustration of this animal may be seen in Ed. 

 Poeppig's Illustrirter Naturgeschichte des Thierreichs, vol, i. fig. 

 24 (Leipzig, 1847), which is taken from some English sonrce with 

 which I am not acquainted. Another woodcut of this animal is in 

 Bock's Unter den Kannibalen auf Borneo, p. 342 : Jena, 1882. 



