_Simia lar_, Phil. Trans., lix., p. 607 (1769.)
_Simia hoolock_, Harlan, Tr. Am. Phil. Soc., iv. (n. s.), p. 52, pl. 2
(1834.)
_Hylobates coromandus_, Ogilby, P. Z. S., 1837, p. 689; Martin, Mammif.
Anim., p. 415 (1841); Is. Geoffr., Arch. Mus., ii. P. 535 (1843); Blyth,
J. As. Soc. Beng., xiii., p. 464 (1844.)
_Hylobates hoolock_, Waterh., Cat. Mamm. Mus. Zool. Soc., p. 3 (1838);
Martin, Mammif. Anim., p. 416 (1841); Is. Geoffr., Arch. Mus., ii., p.
535 (1843); id., Cat. Méth. Primates, p. 9 (1851); Sclater, P. Z. S.,
1860, p. 86, pl. v.; Gray, Cat. Monkeys Brit. Mus., p. 11 (1870); Schl.,
Mus. Pays-Bas, vii., p. 14 (1876); Anderson, Zool. Res. Exped. Yun-nan,
p. 1 (1878; with full synonymy); Blanford, Faun. Brit. Ind., Mamm., p. 5
(1891).
{162}_Hylobates hulok_, Wagner, in Schreb., Säugeth. Suppl., v., p. 20
(1855.)
_Hylobates niger_, Harlan; Ogilby, P. Z. S., 1840, p. 21.
CHARACTERS.--Black all over, except a frontal band, continuous or
interrupted, above the eyes. There is a good deal of variation in this
species, more in the female than in the male, the black being in many
individuals of a brownish tinge.
YOUNG MALES.--Often of a brownish-black, like many of the females.
FEMALE.--With the black generally of a brownish tinge, but often pale or
greyish-yellow; sometimes the upper parts are pale yellow and the under
parts and side of the head brown, and the area round the nude parts of the
face white. (_Anderson._)
DISTRIBUTION.--Lower ranges of Bhutan--its furthest western
range--(_Pemberton_); hill ranges of Upper Assam (_Blyth_), Sylhet,
Chittagong, Aracan.
HABITS.--"I first met with this species in Upper Burma," Dr. Anderson
relates, "in passing through the magnificent defile of the Irawaddy, below
Bhamo, where the river is enclosed by high hills, covered with dense
forest, for about fifteen miles of its course. It was early morning, and
the air was resonant with the loud cries of this Gibbon; large troops were
answering each other from the opposite banks, and the hills echoed and
re-echoed the sound. The Hoolock is also common on the Kakhyen hills, on
the eastern frontier of Yun-nan; and there, too, my attention was called to
them at daybreak, when they passed up from their sheltered sleeping-ground
in the deep and warm valleys to heights of about 4,000 feet. We, in the
middle distance, first caught a faint murmur of voices, but {163}every
minute it became more and more distinct, till at last the whole troop
rushed past in a storm of sound, vociferating _Whoko! whoko!_ and in a few
more minutes their cry was heard far up the mountain-side. Considering that
their progress is almost exclusively arboreal, the rapidity with which they
make their ascent is wonderful.
"Associated with this arboreal habit of progression, we find that _H.
hoolock_ derives its nourishment from leaves, insects, eggs, and birds, the
essential features of sylvan life." It also eats the leaves of _Ficus
religiosa_, the aquatic Convolvulus (_Ipomoea reptans_), and the brilliant
red flowers of the _Canna indica_. It "has a marked partiality," continues
the same naturalist, "for Spiders and their webs, which become tangled in
its long slim fingers, and Orthopterous insects are regarded by it with
special favour, and over which it utters its peculiar cry of satisfaction.
Eggs also are to it a _bonne bouche_. It was first in the Calcutta gardens
that I become aware of the circumstance that small living birds were
devoured by it with a method and eagerness which has left no doubt in my
mind that this species, in its natural state, must be a scourge to the
feathery tribe."
The Hoolock lives in large flocks as a rule, keeping chiefly to the hill
forests. Sometimes, however, an old male may be discovered living by
himself.
They move chiefly by means of their long arms, by which they swing
themselves for prodigious distances from branch to branch, and from tree to
tree. They descend hill-sides at a surprising pace, their descent being
accomplished by grasping bamboos or branches that bend beneath their
weight, and allow them to drop until they can seize the ends of other
bamboos or branches lower on the slope and take another mighty {164}swing
downwards. They also ascend with great rapidity, swinging themselves from
tree to tree. (_Blanford._)
When walking on the ground the Hoolock rests on its hind feet alone, with
the sole flat on the ground and the great-toe widely separated from the
other digits. "They walk erect," writes Dr. Borrough, "and when placed on
the floor, or in an open field, balance themselves very prettily by raising
their hands over their head and slightly bending the arm at the wrist and
elbows, and then run tolerably fast, rocking from side to side; and if
urged to greater speed they let fall their hands to the ground and assist
themselves forward, rather jumping than running, still keeping the body,
however, nearly erect."