THE AGILE GIBBON, 35 
This mode of employing the two sets of limbs is well shown in the Gibbons, and 
in order to fit them in the best manner for their arboreal existence, the thumb of 
the fore-hands is found to be almost destitute of the muscular prominence which is 
popularly known as the “ball” of the thumb, is therefore incapable of grasping, and 
can only follow the direction of the fingers; while the corresponding member on the 
hinder hands is very large and powerful in proportion. 
All the Gibbons are gifted with voices as powerful as their limbs, and the creatures 
seem to lose few opportunities of exercising lungs or limbs. The cry which these animals 
utter is a singular one, loud, and piercing, and has been represented by the syllables 
“wou-wou,” which duplex combination of intonations is often used as a general name 
common to the whole family. Some writers express the sound by the words “oa-oa,” 
and others as “woo-woo,” among which the reader is left to choose. 
The several species of Gibbon do not seem to inhabit the same localities, although 
they all, without an exception, live among trees. Some reside among the mountainous 
ranges and their forests of fir-trees, while others prefer the lower regions of the 
wooded plains and valleys. All, however, agree in their exceeding activity and 
noisy voices, thus proving themselves in every way to be worthy types of their 
mythological lineage. 
All animals which are destined to move with great rapidity, bear a sure sign 
of their destiny in the configuration of their bodies. Active exertions cause the 
heart to beat so fiercely, and the blood to circulate with such rapidity, that a provision 
must be made to give the blood a sufficiency of air to refresh it after its hard labour. 
This can only be done by the gift of very large lungs with plenty of room for their 
free action. Accordingly, the frames of all swift animals are found to be made on 
a similar model, although necessarily modified according to the description of animal. 
Thus, among the well-known living creatures with which all are familiar, we 
may cite the greyhound and the racehorse. Or if we turn to the birds, the falcons 
and swallows are good examples of this formation of body. The chest and fore-part 
of the body are wide and capacious, in order to accommodate the large lungs which 
are necessary for the creature. The limbs which aid the progress “of the animal, 
whether it be bird or beast, are very largely developed, while the subordinate parts 
of the body and limbs are reduced to the smallest size compatible with the well- 
being of their possessor. A greyhound in proper 
health, and ready for the course, has not an ounce 
of superabundant weight about it; neither has the 
racehorse when at the post. So with the falcons 
and swallows, until we come to the hummine-birds, 
which exhibit this modification of limb and body in 
singular perfection. 
The Gibbons are formed on a model of a similar 
nature, their enormously long arms and_ broad 
shoulders contrasted with the smaller hinder limbs 
and thin flank showing that they are capable of 
rapid movement, while the deep and capacious chest 
gives indication that they can endure a lone con- 
tinuance of labcur without being exhausted by it. 
Of the habits of the Gibbons in a wild state, 
very little is known, as they are shy in their nature, 
and by means of their wonderful agility escape 
among the trees ina manner that baftles pursuit or 
observation. As to the species which is represented AGILE GIBBON.—Hylébates Agilis. 
in the accompanying engraving, it seems to be the 
most active of this agile family, and well deserves the name that has been given to 
it. Rather more has been noticed of this wonderful creature, and a further insight 
into its habits has been gained by means of a female specimen, which was captured 
and brought safely to London, where it lived for some time. 
p2 
