The white-handed gibbon (Hylobates albimanus, Vigors and Horsfield) is often confounded with H. Lar. But H. albimanus has a black face, and the general colour of the skin is black, including the inside of the hands and feet. Thick white hair encircles the face, and the backs of the hands and feet are covered with short white or light grey hairs, while the rest of the coat is quite black. The hair of the forearm grows downwards, towards the wrist. The ears of these apes are almost of the shape of an equilateral triangle. The helix of the ear runs like a flap round its free outer edge. The anti-helix passes through the centre of the slightly depressed external surface of the ear, of which the whole arrangement does not essentially differ from that of the ear of other anthropoids. The cartilaginous substance of the organ is a good deal inflected, broad behind and in the upper part, dividing into two limbs in front and below. There are indications of the tragus and anti-tragus. The detached lobule of the ear is absent (Fig. 11). This structure of the external ear is common to other species of gibbons, although in many cases the upper part of the helix is wrinkled, and the anti-helix is sometimes more fully developed, and more like that of the human ear.

The face in this species is small. The supra-orbital arches are strongly developed, and almost join in the centre. The eyes are large, dark, and have a mild and placid expression. The cheeks are prominent in the region of the zygomatic arch, and depressed below it. The bridge of the nose is imbedded between the cheeks, which, especially when seen in profile, take a slightly conical form. The nose is covered with cross-folds. Its cartilage is of the shape described in the former species, and so are the upper lip and chin (Fig. 10). Long, bristly hairs stand out on the supra-orbital arches and upper lip, and short, thin hairs cover the end of the nose. The white hairs which encircle the face grow like a beard on the chin. The whole face has a melancholy, almost tearful expression. The neck is short, the trunk drawn out. On the long, narrow hand there is a short thumb, laterally compressed, which does not quite reach to the metacarpo-phalangeal joint. The ball of the last phalanx forms a thick, rounded pad, which is repeated in a lesser degree on the under side of the first phalanx of the thumb, and on its ball. The thumb-nail is bent back, as unlike a claw as the flattened, long, and narrow nails of the other fingers. The middle finger is only a little longer than the first, and the fourth not much shorter than the third finger (Fig. 12).

The foot is neatly made, short and narrow, without a projecting heel. The great toe is very long, reaching almost to the last phalanx of the second toe. The sole of the foot, and the under side of the great toe, especially its last joint, are provided with thick, rounded pads. The middle toe is not much longer than the second, the fourth is shorter again, and the fifth is only half as long as the fourth. There is only a very short web between the roots of the fingers, but it extends much further on the toes (Fig. 13). This species of ape is found in Further India.

The wauwau (Hylobates agilis, F. Cuvier, Fig. 14), an ape of a rare species, may, according to Duvaucel, be recognized by his prominent supra-orbital arches, sunken eyes, a moderately flat nose, and large nostrils with lateral openings. The face of the male is hairless, and of a bluish black; that of the female is brown. The face is encircled by thick, whitish hair, through which the ears are only partly visible. There are a few black hairs on the chin. In the male the head, belly, inner surface of the arms and of the thighs are dark brown. The neck and shoulders are of a lighter shade, and the hair on the heels is dun or whitish. The backs of the hands and feet are dark brown. The sides of the posteriors and the backs of the thighs are brown, chestnut, or white. In the female the white hair which encircles the face is shorter, and verges on dun colour. The young animals are light yellow or brown. This animal inhabits the island of Sumatra.

The grey gibbon (Hylobates leuciscus, Kuhl) is covered with a thick, long, and woolly coat, with scattered hairs which are curly, and have two or three rings of dark colour on a light ground. The upper part of the head is black; light, or sometimes white, hair encircles the blackish face. The general colour is dun. The front of the throat, the breast, and belly are of a lighter shade; while the back of the neck, the shoulders, upper arms, and thighs are darker. A brown or black stripe runs down the breast and belly from the armpits. The insides of the hands and feet are black. The colour of young specimens is more uniformly grey or dun. This animal is found in Java and Sumatra.

The hulock, otherwise called yulock or yoluck (Hylobates Hoolock, Harlan), has, in its adult condition, a prognathous face with prominent supra-orbital arches, a long, low bridge to its nose, with high, narrow nostrils, and a very small upper lip. In aged animals there are two oblique folds over the eyes, of a light grey colour. The rest of the hairy coat, the face, hands, and feet are black, or, in the younger animals, brownish black, with grey extremities. A line of grey extends from the breast downwards over the belly. This animal inhabits the mountainous district of Assam.

The unko (Hylobates Rafflesii, Is. Geoff. Saint-Hilaire) is of a black colour, shading into reddish brown on the back and sides. Hair, of a grey colour in the male and white in the female, encircles the face. This ape is a native of Sumatra.

The dun-coloured gibbon (Hylobates entelloides, Is. Geoff. Saint-Hilaire) is so called from its coat, which is thick and woolly, and furnished with long hairs of a greyish yellow or dun colour. This coat is somewhat darker on the inner surface of the arms and on the neck, where it shades into reddish yellow. The growth of hair surrounding the face is lighter, verging upon white. The female is generally more yellow in colour than the male, and the hair on her face is of a reddish yellow rather than white, but not without a trace of white hairs. The face and the bare places on the hands and feet are black. Between the second and third toes there is a connective web reaching as far as the first joints. This animal inhabits the Malacca peninsula. The name of the species is derived from its assumed likeness to the Indian hanuman (Semnopithecus Entellus, F. Cuvier), of which an illustration is given in the background to the right of Fig. 14.

The white-bearded gibbon (Hylobates leucogenys, Ogilby9) is remarkable for the long, erect hairs which grow on the upper and back part of the scalp, and for the long white beard on the cheeks and chin, which joins the thick growth above the eyes. The rest of the body is dark black. Its native place is doubtful.

The general colour of the tufted gibbon (Hylobates pileatus, J. E. Gray) is black, shading into grey on the shoulders, back, and thighs. A white ring surrounds the hands, feet, face, and scalp; and there is also a patch of white on the sexual organs, and often a patch of black on the breast. The whiskers are black. In other respects the animal varies according to its sex and age. It is found in Siam and Kambodja.10

The dark grey gibbon (Hylobates funereus, Is. Geoff. Saint-Hilaire) is of an ashen grey colour on the upper and outer side of its limbs, verging into brown; and on the under side it is dark brown. There is a narrow strip of light grey round the face, with a darker band round the back of the head. It is found in the island of Sulu.11

In addition to these species of gibbons of which we have given a brief account, there are several others—as, for example, Hylobates concolor (Harlan), from Borneo; H. Muelleri (L. Martin), from the same place; H. choromandus (Ogilby), from India, and many others. But since our space is limited, the description given above must suffice for a diagnosis of the species.