GIBBON, a tailless anthropoid ape of the East Indies, the several species of which con stitute the genus Hylobates of the family Simi ida.. They are nearly allied to the orangs and chimpanzees, but are smaller, of more slender form, and their arms are so long as almost to reach the ground when the animal assumes an erect posture; there are also naked callosities on the buttocks. In general the gibbons are the lowest among the anthropoid apes, and connect them with the Old World monkeys by way of the semnopithecine group. (See LANGUR). The gibbons are inhabitants of forests, their long arms enabling them to swing themselves from bough to bough, which they do to wonderful distances and with extreme agility. They can not, however, move with ease or rapidity on the ground. The conformation of the hinder ex tremities adds to their difficulty in this, while it increases their adaptation to a life among the branches of trees, the soles of the feet being much turned inward. None of the gibbons are
of large size, averaging about three feet tall. Eight or ten species are named in the books, but probably increased knowledge will reduce this number. One, the siamang (H. syndactylus), has the second and third digits of the hind limb partly united, and the hair of the upper arm pointing downward, while that on the forearm grows upward. It is a native of Sumatra, and has been set apart as the type of a separate genus (Siamanga) by some naturalists. The other species have the digits mostly free; they are natives of Cambodia, the Malay Peninsula, Sumatra and Java, and are known as Lars, hoolocks, agile gibbons, white-handed etc., but are much alike. One species is called in imitation of the howling cry that is characteristic of all. Consult any work on natural history and Hartmann's poid Apes) (1886).