[Illustration: THE SIAMANG GIBBON.]
{167}The frontal lobes of the brain are broad and much flattened, and not
full and rounded as in the Orang. The olfactory bulbs project forward,
slightly beyond the frontal lobes of the cerebrum; the occipital lobes are
much reduced, while the large cerebellum projects distinctly backwards from
below the cerebrum--characters in which this very highly organised member
of the genus shows a retrogressive development, thus differing from all the
other Man-like Apes, in all of which the cerebrum entirely covers both the
olfactory lobes in front, and the cerebellum behind.
The large laryngeal sac, communicating by two openings with the larynx, and
formed by the extension of the thyro-hyoid membrane, distinguishes this
from all the other Gibbons.
DISTRIBUTION.--The Siamang is confined to the island of Sumatra. It has
been recorded from Malacca and Tenasserim; but some doubt exists as to the
accurate determination of the individuals referred to, no really authentic
specimen having yet been obtained out of Sumatra.
HABITS.--The Siamang is gregarious, frequenting the great forest-trees from
200 to 300 feet above the sea up to 3,000 or 4,000 feet.
I made the acquaintance of this species in Southern Sumatra, and during my
stay in that island had various opportunities of observing many of them in
their homes. It was not uncommon to come suddenly on a colony of them both
in the forest and among the tall isolated outliers, when they happened to
be covered with fruit. The satiated members of the company {168}might then
be often seen hanging by one arm from a bare branch, with perhaps eighty
unobstructed feet between them and the ground, making the woods resound
with their loud barking howls, uttered apparently for pure love of making a
noise. On one occasion a young one, found clinging to its mother, which had
been shot, was brought in alive. It had been only stunned by a pellet on
the head, and had no bones broken. In a very short time it became a most
delightful companion. The following observations in reference to it are
taken from the writer's Journal: "Its expression of countenance is most
intelligent and often very human; but in captivity it generally wears a sad
and dejected aspect, which quite disappears in its excited moods. With what
elegance and gentleness it takes with its delicate taper fingers whatever
is offered to it! Except for their hairiness, its hands, and, in its youth
at all events, its head, seem to me more human than those of any other
Ape's. It rarely, however, brings its thumb into opposition with the other
fingers, but usually clasps the whole hand, without that digit, on an
object. It will never put its lips to a vessel to drink, but invariably
lifts the water to its mouth, by dipping in its half-closed hand and then
awkwardly licking the drops from its knuckles. It generally sits with its
arms crossed over its chest, and its fingers overlaid behind its head. The
gentle and caressing way in which it clasps me round the neck with its long
arms, laying its head on my chest, and watching my face with its dark brown
eyes, uttering a satisfied crooning sound, is most engaging. Although it
often inflates its laryngeal sac, it rarely gives utterance to more than a
yawn-like noise or suppressed bark; but this dilatation has no reference
apparently to its good or bad temper, although, when very eager and
{169}impatient for anything, a low pumping bark is uttered. Every evening
it makes with me a tour round the village square, with one of its hands on
my arm. It is a very curious and ludicrous sight to see it in the erect
attitude on its somewhat bandy legs, hurrying along in the most frantic
haste, as if to keep its head from outrunning its feet, with its long free
arm see-sawing in a most odd way over its head to balance itself, and now
and again touching the ground with its finger-tips or its knuckles. That
they can leap the great distances from tree to tree ascribed to them is no
doubt an accurate observation; but they appear to be sometimes
terror-stricken and unable to perform these feats to save their lives.
During the felling of the forest near this village, a small colony of
Siamangs got isolated on a tree separated from the next clump by some
thirty feet or so. They scampered up and down in the crown of the tree
howling in the most abject terror at every stroke of the axe; yet they
would not venture to leap the intervening space, and even, when the tree
was falling, they did not attempt to save themselves by springing to the
ground, but perished in its downfall.
"When teething my companion suffered severely--as the human infant so often
does--both locally and constitutionally, as indicated by boils and inflamed
finger-tips. On lancing and poulticing the latter, and extracting some of
its obstructing teeth, the poor creature seemed greatly relieved, and I was
delighted to watch it recover, without contracting for me any antipathy for
the pain I had inflicted on it, but rather the reverse." At a later date
the following extract occurs:--
"During my march to the coast my Siamang accompanied me, occupying, with
the most grave demeanour, a seat on one of the packages carried in the
rear, near to myself. Here it {170}sheltered its head, to the amusement of
all whom we met, under a Chinese umbrella, which I had bought for it to
protect it from the midday sun, and for which, after every halt, it held
out its hands in the most knowing way, screaming lustily if the porters
dared to move on before it had comfortably arranged itself. To my intense
regret, a misadventure put an end to a most charming existence, before I
could send it to London."