The largest species of these animals, which inhabit part of the continent and of the islands of Asia, is the siamang (_Hylobates syndactylus_, F. Cuvier).[8] 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 insignificant 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 together 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. The lar (_Hylobates Lar_, Illig) is another species of gibbon. The structure of the body is much more slender than that of the animal just described; the head is round, the eyes are large, the nose projects from its depressed surroundings with only a very slight ridge, and the cartilaginous end is shaped like a triangle with unequal sides. This triangular end is divided by a longitudinal furrow, and the small nostrils converge downwards and inwards, and are divided from each other by a thin partition. The structure of the upper lip is peculiar. In the centre, just below the base of the nasal partition, it is depressed, and divided into two symmetrical lateral halves by a vertical furrow. Each of these halves forms a rounded edge, overhanging the small lower lip. Above the upper lips, between them and the zygomatic arch, which slopes away below the lower eyelids, there are the flat, depressed cheeks. The small chin presents itself below the central cleft of the upper lips and their convex rims. The face of this gibbon, of which the general appearance is very singular, is surrounded by a circle of thick hair, which resembles the circular hood of an Eskimo. This characteristic form of the head, both generally and in detail, is not confined to the lar, but applies to other species of gibbons, including the siamang (see Figs. 11 and 15). It is a feature which distinguishes the long-armed apes, almost at the first glance, from the other forms of anthropoids already described. The colour of the lar’s face is reddish brown or tawny; the hair which surrounds it