| HYLOBATES LAR. HYLOBATES HOOLUCK. |
DESCRIPTION.—"This species is generally recognisable by its pale yellowish, almost white hands and feet, by the grey, almost white, supercilium, whiskers and beard, and by the deep black of the rest of the pelage."—Anderson.
SIZE.—About same as H. hooluck.
It is, however, found in every variety of colour, from black to brownish, and variegated with light-coloured patches, and occasionally of a fulvous white. For a long time I supposed it to be synonymous with H. agilis of Cuvier, or H. variegatus of Temminck, but both Mr. Blyth and Dr. Anderson separate it. Blyth mentions a significant fact in distinguishing the two Indian Gibbons, whatever be their variations of colour, viz.: "H. hooluck has constantly a broad white frontal band either continuous or divided in the middle, while H. lar has invariably white hands and feet, less brightly so in some, and a white ring encircling the visage, which is seldom incomplete."[3]
3 There is an excellent coloured drawing by Wolf of these two Gibbons in the 'Proceedings of the Zoological Society,' 1870, page 86, from which I have partly adapted the accompanying sketch.
H. lar has sometimes the index and middle fingers connected by a web, as in the case of H. syndactylus (a Sumatran species very distinct in other respects). The very closely allied H. agilis has also this peculiarity in occasional specimens. This Gibbon was called "agilis" by Cuvier from its extreme rapidity in springing from branch to branch. Duvaucel says: "The velocity of its movements is wonderful; it escapes like a bird on the wing. Ascending rapidly to the top of a tree, it then seizes a flexible branch, swings itself two or three times to gain the necessary impetus, and then launches itself forward, repeatedly clearing in succession, without effort and without fatigue, spaces of forty feet."
Sir Stamford Raffles writes that it is believed in Sumatra that it is so jealous that if in captivity preference be given to one over another, the neglected one will die of grief; and he found that one he had sickened under similar circumstances and did not recover till his rival (a Siamang, H. syndactylus) was removed.
[NO. 3. HYLOBATES SYNDACTYLUS.]
The Siamang.
HABITAT.—Tenasserim Province, Sumatra, Malayan Peninsula.
DESCRIPTION.—A more robust and thick-set animal than the two last; deep, woolly, black fur; no white supercilium nor white round the face. The skull is distinguished from the skull of the other Gibbons, according to Dr. Anderson, by the greater forward projection of the supraorbital ridges, and by its much deeper face, and the occipital region more abruptly truncated than in the other species. The index and middle toes of the foot are united to the last phalange.