74: 
VERTEBRATA. 
Genus GIBBON : Hylohates, or Wood-walkers. — These approximate the monkeys by the 
naked callosities on their rumps, but the absence of tails and cheek-pouches places them 
among the apes. They are rarely more than four feet in height, and are distinguished by 
their long arms, which reach the ground when they are in an erect posture. There are several 
species, which are found all over India and the 
adjacent islands, to which they are confined. 
The forests are their haunts, and they are rai'ely 
seen at a distance from them. Gregarious, but 
shy and timid, they keep up a noisy concert, 
resembling in this respect the Howling Monkeys 
of America, and some of them having guttural 
sacs like that tribe. In the forest the activity of 
certain species is great, and they make way on 
the trees with their long arms and lengthened 
feet, most rapidly ; but when surprised in open, 
plain ground they are almost helpless. Some 
species appear to be more sluggish ; but even 
these make good use of their acute eyes and ears, 
and are generally off before an enemy approaches 
near enough to capture them. 
The "Wou-Wou, or Active Gibbon, H. agilis, 
may be taken as an example of the genus. It 
has the forehead very low ; orbital arches very 
projecting ; face blackish-blue in the male, and 
brown in the female ; in the former a white band 
over the eyes, which unites with the whitish 
whiskers ; hair of the body fine, except about 
the neck, where it is longer, and inclined to be 
woolly and curled; upper part chocolate-brown; 
back and fore part of the thighs yellowish- mourning gibbon. 
brown, but the color varies a good deal, according to the sex and age — the young being paler than 
the adults and aged, and the very young uniformly of a yellowish-white; height about two feet 
seven or eight inches. This species are very agile in their habits. As soon as they reach the 
forest they set pursuit at defiance, swinging, leaping, and throwing themselves from tree to tree 
with a rapidity which seems hke flying. Notwithstanding the want of the guttural sac, they 
howl in a manner very nearly resembling the siamang, which has one. In captivity they are not 
very lively — as might indeed be expected, from the impossibility of their exerting that freedom of 
motion on which their vivacity in a state of nature depends; but though timid they are soon 
reassured, take pleasure in being caressed, and become familiar and even playful. They have 
great curiosity, and a greedy appetite. This species is found in the forests of Sumatra, where it is 
named TJnga'puti. 
The HooLOCK, H. lioolock^ is little known. "We are chiefly indebted to Dr. Borroughs for what 
knowledge we have on the subject. He has furnished a most interesting account of three individ- 
uals of the species which he had an opportunity of observing in a state of confinement. One of 
them, a male, showed a most amiable and docile disposition ; and a young female, which died 
early, was equally gentle and pacific. 
The Siamang, H. syndactylus. The animals of this species are black, and have two naked 
folds of skin on the neck, which are occasionally inflated. The hair is long and soft. They 
are very common in Sumatra, and are generally found gathered in large troops, conducted, it is 
said, by a chief, whom the Malays believe invulnerable. Thus assembled at sunrise, and again at 
sunset, they vie with each other in making the most dreadful cries, perfectly stunning to those 
accustomed to them, and frightful in the highest degree to strangers. At other times they ap- 
pear to be perfectly quiet — so long, at least, as they are undisturbed. Among them, maternal 
