Part 12

The group of Tree-walkers, as the term _Hylobates_ signifies, {149}embraces the smallest-sized, the slenderest-bodied, the longest-limbed, and the most perfectly arboreal of all the Man-like Apes. All are covered with thick woolly hair, which, on the arms and fore-arms, converges (except in _H. agilis_) towards the elbow.

Their head is small and round, and the face compressed. Except the Orangs, the Gibbons have the longest arms of all the Apes, so long that when they stand erect the points of their fingers can touch the ground. Compared with the spinal column, their arms are as 19 to 11, while the legs are one-third longer than it. The fore-arm is much longer than the arm itself; the hand is longer than the foot, and the thumb is very long in proportion to the hand. The knee is free from the side of the body, and the great-toe is well developed and nearly one-half the length of the foot. The nails of both the thumb and the great-toe are flat. Callosities, which are wanting in all the other genera, are present in _Hylobates_, but are very small.

In the skull the occiput is convex; the orbits are very large and deep, and the supra-orbital ridges prominent. The canine teeth are much larger than the others, and equally large in both sexes. They are generally the last of the permanent teeth to come in, but in the Gibbons they generally precede, or are developed along with, the last molar.

The vertebral column is nearly straight, presenting but little of the spinal curvature seen in Man; it has also in the dorso-lumbar region one vertebra more than in the human skeleton. The articulating head of the arm-bone (_humerus_) loses the direction it had among the Monkeys, and looks upward and forward as in Man. The wrist (_carpus_) has nine bones, as in the lower _Anthropoidea_. The skeleton of the hand is more {150}than half the length of the spine, and the foot is slightly under half its length. The Gibbons have two pairs of ribs more than Man. The ends of the ischial bones are much everted to support the callosities.

With regard to the brain, this genus is remarkable for the great reduction of the occipital lobes of the cerebrum.

The tongue is very similar to that in Man, but it is furnished with a sub-lingual process like that already described among some of the Lemuroids. The Gibbons (except the Siamang) have no laryngeal sacs. The stomach closely resembles the human organ.

The Gibbons are very delicate, and rarely live long in confinement, even in their own country. They are in general highly intelligent, very gentle, and become most affectionate and engaging animals if kindly treated. They are, however, occasionally irascible and ill-tempered, especially when adult.

Their feats of climbing and leaping are almost proverbial. It would be impossible to excel them as acrobats. When walking on the ground they assume the erect posture, putting the soles of their feet to the ground, separating the thumb and the great-toe widely from the neighbouring digits.

"They walk erect, with a waddling or unsteady gait, but at a quick pace; the equilibrium of the body requiring to be kept up, either by touching the ground with the knuckles, first on one side then on the other, or by uplifting the arm so as to poise it. As with the Chimpanzee, the whole of the narrow, long sole of the foot is placed upon the ground at once and raised at once, without any elasticity of step." (_Martin._)

Their voice is very powerful and can be heard at a great distance, especially when they are howling in chorus. The {151}Wau-Wau and the Siamang, the one without, and the other with, a laryngeal sac, are equally vigorous in this respect.

The female produces but a single young one at a birth, of which she takes the greatest care. She carries it about, clinging to the under side of her body, for many months. It is said that she even takes it to the waterside from time to time, and with much solicitude, and in spite of its cries and resistance, washes its face.

The Gibbons frequent the great upland forests; but the Siamang (_H. syndactylus_) may be met with at quite low levels and close to the coast. Their food consists of fruit, leaves, and insects, eggs of birds, and apparently birds and lizards, and especially spiders. They drink either by putting the mouth down to the water, or by dipping in their hands and thus carrying it to their mouths.

The Gibbons are confined to two Sub regions of the Indian Region. With the exception of the Siamang, all the so-called species of _Hylobates_ are so closely allied to each other, and differ by characters of such slight importance, that they seem to be hardly worthy of specific distinction. (_Thomas._)

I. THE AGILE GIBBON. HYLOBATES AGILIS.

_Pithecus lar_ (nec L.), Geoffr., Ann. Mus., xix., p. 88 (1812).

_Hylobates agilis_, F. Cuv., Hist. Nat. des Mammif., Sept. 1821, pls. v., vi.; Müller, Tijdschr. Nat. Gesch., ii., p. 326 (1835); Martin, Mammif. Anim., p. 416 (1841); Fry, P. Z. S., 1846, p. 11; Gray, Cat. Monkeys Brit. Mus., p. 12 (1870); Schl., Mus. Pays-Bas, vii., p. 17 (1876); Anderson, Zool. Res. Exped. Yun-nan, p. 9 (1878; with full synonymy).

_Pithecus agilis_, Desmar., Mamm., p. 532 (1820).

{152}_Simia lar_ (nec L.), Raffl., Tr. Linn. Soc., xiii., p. 242 (1822).

_Hylobates lar_ (nec L.), F. Cuv., Hist. Nat., Mamm., pls. 7, 8 (1824); Blyth, J. A. S. Beng., xliv., ex. no., p. 2 (1875).

_Hylobates variegatus_, Temm., Monogr. Mamm., i., p. xiii. (1827); Wagner in Schreb. Säugeth. Suppl. v., p 16 (1855); H. O. Forbes, Nat. Wand. East. Arch., p. 156 (1885).

_Hylobates rafflesii_, Is. Geoffr., Cat. Méth. Primates, p. 8 (1851); Gray, Cat. Monkeys Brit. Mus., p. 11 (1870).

_Hylobates pileatus_, Gray, P. Z. S., 1861, p. 136, pl. xxi.; id., Cat. Monkeys Brit. Mus., p. 10 (1871); Anderson, Zool. Res. Exped. Yun-nan, p. 6 (1878).

CHARACTERS.--Face black; colour entirely black, but becoming brown on the back and sides, and with a white superciliary band, and sometimes ashy-grey cheeks.

This is the typical form of the species in Mid-Sumatra, where the present writer had the opportunity of examining it alive. It was with difficulty distinguished from _H. syndactylus_, except from its size and the presence of the white superciliary band.

Other specimens (but none of them met with to the south of the Moesi river by the present writer) have been described, with the occiput, the back from immediately behind the shoulders, the flanks, the hips, and the outer surfaces of the fore- and hind-limbs, pale yellow. The shoulders, chest, and belly, and the inside of the limbs and feet dark brown; eyebrows and whiskers pale grey. (_Anderson._)

The variety described as _H. pileatus_ is distinguished by a black cap-like patch on the top of the head; the chest, throat, and belly black; the back of the head, the upper surface of the body, the limbs and area round the black cap grey. This variety may also be entirely white, except for the coronal cap {153}and chest being black, and the back brown; or the pervading colour may be brown, the sides of the face and the under surface black, and the whiskers white. The index and middle fingers are occasionally webbed together.

All the hairs on the arm and fore-arm converge towards the wrist.

DISTRIBUTION.--This species is confined to Sumatra and to Siam. In the former country it is known by the name of "Ongka" by the Malays, who, with the keen powers of observation they possess in regard to all natural objects, recognise two varieties, the white or yellow variety--"Ongka putih," and the black one--"Ongka itam" (_H. rafflesi_). The capped variety (_H. pileatus_) with its variously coloured forms inhabits Siam.

HABITS.--The habits of the "Ongka" are very similar to those of the Wau-wau, or the Siamang (_H. syndactylus_). The natives, however, aver that it is much more silent, rarely howling as either of these other two species do. They are also seen generally in quite small troops, and often in pairs only.

"It is almost impossible," writes Mr. Martin of a specimen that lived formerly in the Zoological Gardens, "to convey in words an idea of the quickness and graceful address of her movements: they may, indeed, be termed aërial, as she seems merely to touch, in her progress, the branches among which she exhibits her evolutions. In these feats her hands and arms are the sole organs of locomotion; her body hanging as if suspended by a rope, sustained by one hand (the right, for example), she launches herself by an energetic movement to a distant branch, which she catches with the left hand. But her hold is less than momentary; the impulse for the next {154}launch is acquired; the branch then aimed at is attained by the right hand again, and quitted instantaneously, and so on, in alternate succession. In this manner spaces of twelve and eighteen feet are cleared with the greatest ease, and uninterruptedly for hours together, without the slightest appearance of fatigue being manifested; and it is evident that if more space could be allowed, distances very greatly exceeding eighteen feet would be as easily cleared.... Sometimes on seizing a branch in her progress, she will throw herself, by one arm only, completely round it, making a revolution with such rapidity as almost to deceive the eye, and continue her progress with undiminished velocity. It is singular to observe how suddenly this Gibbon can stop, when the impetus given by the rapidity and distance of her swinging leaps would seem to require a gradual abatement of her movements. In the very midst of her flight a branch is seized, the body raised, and she is seen, as if by magic, quietly seated on it, grasping it with her feet.... A live bird was let loose in her apartment; she marked its flight, made a long swing to a distant branch, caught the bird with one hand in her passage, and attained the branch with her other hand; her aim, both at the bird and the branch, being as successful as if one object only had engaged her attention. It may be added, that she instantly bit off the head of the bird, picked its feathers, and then threw it down, without attempting to eat it."

II. THE WAU-WAU GIBBON. HYLOBATES LEUCISCUS.

A. _Javan Race_ (_H. leuciscus_).

_Simia leucisca_, Schreber, Säugeth. i., pl. iii. b. (1775).

_Pithecus leuciscus_, Geoffr., Ann. Mus., xix., p. 89 (1812).

{155}_Hylobates leuciscus_, Kuhl, Beitr. Zool., p. 6 (1820); Desmar. Mamm., p. 51 (1820); Martin, Mammif. An., p. 416 (1841); Is. Geoffr., Cat. Méth. Primates, p. 7 (1851); Wagner, Schreb., Säugeth. Suppl. v., p. 16 (1855); Gray, Cat. Monkeys Brit. Mus., p. 15 (1870); H. O. Forbes, Nat. Wand. East. Arch., p. 70 (1875); Schl., Mus. Pays-Bas, vii., p. 19 (1876); Anderson, Zool. Res. Exped. Yun-nan, p. 7 (1878; with full synonymy).

B. _Bornean Race_ (_H. concolor_).

_Simia concolor_, Harlan, Journ. Acad. Nat. Sc. Phil., v., p. 229 pl. ii. (1827).

_Hylobates harlani_, Less., Bull. des Sc. Nat., xiii., p. 111 (1827).

_Hylobates concolor_, Schl., Essai Phys. Serp., p. 237 (1837); S. Müller, Verhand. Gesch., p. 48 (1841); Blyth, J. A. S. Beng., x., p. 838 (1841); Martin, Mammif. An., p. 417 (1841); Fry, P. Z. S., 1846, p. 15; Wagner in Schreb. Säugeth. Suppl. v., p. 17 (1855; in part); Schleg., Mus. Pays-Bas, vii., p. 20 (1876); Anderson, Zool. Res. Exped. Yun-nan, p. 11 (1878).

_Hylobates mülleri_, Martin, Mammif. Anim., p. 444 (1841); Is. Geoffr., Cat. Méth. Primates, p. 7 (1851); Schlegel, Mus. Pays-Bas, vii., p. 21 (1876); Anderson, Zool. Res. Exped. Yun-nan, p. 8 (1878; with full synonymy); Hose, Mammals of Borneo, p. 6 (1893).

_Hylobates funereus_, Is. Geoffr., C. R., xxxi., p. 874 (Dec., 1850); Wagner in Schreb. Säugeth. Suppl. v., p. 18 (1855).

_? Hylobates fuscus_, Winslow Lewis, Bost. Journ. N. Hist., i., pt. i., p. 32, pls. i., ii. (1834).

CHARACTERS.--Fur thick, long and woolly. General colour ashy-grey, paler on the lower back and rump; hair round {156}the face grey; superciliary streak white; top of the head black; fingers and toes black.

This species has been found to possess occasionally a supernumerary finger on each hand.

DISTRIBUTION.--The Indo-Malayan Sub-region. Java, Borneo, and the Sulu Archipelago between Borneo and the Philippines.

HABITS.--The Wau-Wau--the Malay name for this Gibbon--is one of the first of the Quadrumana that makes its presence known to the traveller in Java, when he reaches its upland forest regions. In the evening, just about sundown, and more especially in the early morning commencing before sunrise and finally ceasing when the sun is above the tops of the trees, he will be surprised by a sudden outbreak of what appears to be now the loud plaintive wailings of a crowd of women, now the united howling of a band of castigated children. The present writer's first acquaintance with this charming genus of Monkeys was made among the Kosala hills in Western Java, and it will ever remain with him as one of many most pleasant recollections of a long tropical sojourn. Their "woo-oo-ut--woo-ut--woo-oo-ut--wut-wut- wut--w[)u]t-w[)u]t-w[)u]t," always more dolorous on a dull heavy morning previous to rain, is just such a cry as one might expect from the sorrowful countenance so characteristic of the species of _Hylobates_. The Wau-Wau has a wonderfully human look in its eyes; and it was with great distress that the writer witnessed the death of the only one he ever shot. Falling on its back with a thud on the ground, it raised itself on its elbows, passed its long taper fingers over the wound, gave a woeful look at them and at his slayer, then fell back at full length--dead--"saperti orang" (just like a man), as his Malay companion remarked. He kept in captivity for a short time a specimen which was brought to him by a native, and it {157}became one of the most gentle and engaging creatures possible; but when the calling of its free mates reached its prison house, it used most pathetically to place its ear close to the bars of its cage and listen with such intense and eager wistfulness that it was impossible to retain it in durance any longer. It was accordingly set free on the margin of its old forest home. Strange to say, its former companions, perceiving perhaps the odour of captivity about it, seemed to distrust its respectability, and refused to allow it to mingle with them. Amid the free woods we may hope that this taint was soon lost and that it recovered all its pristine happiness.

In general habits it in no way differs from the other species of _Hylobates_ already described.

In regard to the Bornean specimens of this species, Dr. Anderson makes the following observations: "This species varies from grey to dark yellowish-brown, but the grey tint in certain lights appears pure ashy, and in others of a brownish tint. In some the chest and abdomen are frequently yellow, and this seems to be the character of individuals met with on the west coast of Borneo, while those inhabiting the meridional parts of the island have the hands and fore part of the body of a black-brown or reddish-brown. In both of these varieties there is a yellowish-white superciliary streak. The last of them leads into the varieties of _Hylobates_ from the neighbouring islands of Sulu, to the north-east of Borneo, in which the upper parts of the body are either grey or brownish, the lower part of the back and the loins being a little more clear than the rest." The outer surface of the limbs, the back part of the head, the supercilium, and the sides of the face are more or less pure ashy-grey. "Specimens of this Gibbon obtained by me," writes Mr. Charles Hose, who is well known for his Bornean researches, {158}"at Claudetown, and now in the British Museum, show that the colouring in different parts of the body must be considered of little importance, as I obtained eleven specimens, five of which were in the same troop and the other six from the same locality, varying in colour as much as it is possible for them to do; some had yellowish backs and black chests, others black backs with yellowish chests, and some were nearly black all over; whilst others were almost a complete silver-grey. I, therefore, come to the conclusion that _H. muelleri_ and _H. leuciscus_ cannot be separated. The peculiar bubbling noise they make is similar. I think it very unlikely that two distinct species should be so constantly found together as they are in Sarawak.

"The natives call the silver-grey variety 'Emplian' or 'Wa-Wa,' and the dark one, 'Emplian arang' (coal), because of its colour."

III. THE WHITE-CHEEKED GIBBON. HYLOBATES LEUCOGENYS.

_Hylobates leucogenys_, Ogilby, P. Z. S., 1840, p. 20; Blyth, J. A. S. Beng., x., p. 838 (1841); Martin, Mammif. Anim., p. 445, _cum fig._ (1841); Is. Geoffr., C. R., xv., p. 717 (1842); id., Arch. Mus., ii., p. 535 (1843); Gray, Cat. Monkeys Brit. Mus., p. 11 (1870); Schl., Mus. Pays-Bas, vii., p. 13 (1876); Scl., P. Z. S., 1877, p. 679, pl. lxx.; Anderson, Zool. Res. Exped. Yun-nan, p. 6 (1878; with synonymy).

CHARACTERS.--Fur glossy, thick, and woolly; the hair of the upper and back part of the head standing vertically erect; the face, chin, and ears black; round the face from the level of the eyes and meeting below the chin runs a white border, forming {159}whiskers and beard; elsewhere the colour is entirely black. Length of the body, 26 inches.

DISTRIBUTION.--Siam.

HABITS.--This rare species is very active and gentle in confinement. It will hang suspended, as Martin observed in the first specimen brought to Europe, from a branch for the whole day, except when asleep or reposing.

The type specimen was described in 1840,--its skin being preserved in the British Museum; but it was not till 1877--after a lapse of thirty-seven years--that a second specimen was brought to this country. It was sent to the Zoological Gardens by Mr. W. H. Newman, H.B.M. Consul at Bankok.

IV. THE WHITE-HANDED GIBBON. HYLOBATES LAR.

_Homo lar_, Linn., Mantiss. Plant., App., p. 521 (1771).

_Simia longimana_, Wagner in Schreb. Säugeth. i., p. 66, pl. iii., figs. 1, 2 (1775); Erxl., Syst. Reg. An., p. 9 (1777).

_Simia lar_, Bodd., Elench. An., p. 55 (1785); Fischer, Syn. Mamm., p. 12 (1829; in part).

_Pithecus lar_, Latr., Hist. Nat. Buff., xxxvi., p. 276 (1809).

_Pithecus varius_, Latr., _op. et loc. cit._

_Pithecus variegatus_, Geoffr., Ann. Mus., xix., p. 88 (1812).

_Hylobates lar_, Illig., Abhandl. Akad. Berl., p. 88 (1815); Martin, Mammif. Anim., pp. 416, 433 (1841); Blyth, J. A. S. Beng., x., p. 838 (1841); Gray, Cat. Monkeys Brit. Mus., p. 10 (1870); Scl., P. Z. S., 1870, p. 86, pl. v.; Schlegel, Mus. Pays-Bas, vii., p. 15 (1876); Anders., Zool. Res. Exped. Yun-nan, p. 5 (1878; with full synonymy); Blanford, Faun. Brit. Ind., Mamm., p. 7 (1891).

{160}_Hylobates variegatus_, Kuhl, Beitr. Zool., p. 5 (1820; young); Desmar., Mamm., p. 51 (1820); Is. Geoffr., Zool. Bélang. Voy., p. 27 (1834).

_Simia albimana_, Vig. et Horsf., Zool. Journ., iv., p. 107 (1828).

_Simia variegatus_, Fischer, Syn. Mamm., p. 11 (1829).

_Hylobates albimanus_, Is. Geoffr., Zool. Bélang. Voy., p. 29 (1834).

_Hylobates entelloides_, Is. Geoffr., C. R., xv., p. 717 (1842).

_Hylobates leuciscus_, Cantor, Ann. and Mag. N. H., xvii., p. 338 (1846).

CHARACTERS.--MALE.--Everywhere deep black, except the face, which is reddish-brown, with the thick hair round it light grey or white, and the hands and feet, which are pale yellow or white; superciliary ridges, whiskers and beard, white. The hair on the fore-arm is nearly erect, with only a very slight forward inclination. The species is subject to great variation, and may be of all shades, from deep black to entirely whitish-yellow (_H. entelloides_).

Head round; the eyes large; the cheeks flat and depressed; the nose slightly projecting, its tip furrowed, and its nostrils small and converging; the upper lip is divided in the centre by a vertical furrow. In very young individuals the top of the ear is markedly pointed.

Skull with the orbital ridges larger, the muzzle shorter, and the teeth smaller than in _H. hoolock_; the second and third toes sometimes united by a membrane.

FEMALE.--Generally similar to the male, but more frequently entirely pale yellow, with the hands and feet paler.

DISTRIBUTION.--Aracan, Lower Pegu, Tenasserim, and the Malay Peninsula.

HABITS.--The White-handed Gibbon inhabits the upland {161}forests as high as 3,500 feet above the sea; living in troops numbering from ten to twenty-five. Its habits are very similar to those of other Gibbons, although Tickell observed that they were less light and active than the Hoolock, and had a different voice. It is said to drink, as the Siamang does, by dipping its hands into the water, and not to put its mouth down to it like the Hoolock. "So entirely does it depend on its hands for locomotion amongst trees," remarks Dr. Blanford, "that it carries everything in its feet. Tickell, from whom I take these details, says that he has seen a party of _H. lar_ escape thus with their plunder from a Karen garden in the forest." "The young are born in the early part of the cold season," continues Dr. Blanford, "and each sticks to the body of its mother for about seven months, after which it begins gradually to shift for itself."

V. THE HOOLOCK. HYLOBATES HOOLOCK.

_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.