Chapter XXIX: The Moupin Langur. Semnopithecus Roxellanæ

_Semnopithecus roxellanæ_, A. Milne-Edwards, C. R., lxx., p. 341 (1870);
Schl., Mus. Pays-Bas, vii., p. 65 (1876).

_Rhinopithecus roxellanæ_, id., Rech., Mammif., p. 233, pls. xxxvi.,
xxxvii. (1868-1874); Blyth, Mamm. Burm., p. 11 (1875).

_Semnopithecus_ (_Nasalis_) _roxellanæ_, Anders., Zool. Res. Exped.
Yun-nan, p. 43 (1878).

CHARACTERS.--Face naked, nose depressed in the middle, the tip elevated and terminating in a singular leaf-like point; sides of the face and brows clothed with a thick ruff, which extends in a line across the face towards the nose; face green; the frontal region, sides of the face, auricular region, sides of the neck and shoulder, chin, chest, inner side of the fore-limbs, and upper aspect of the feet, yellow; top of head greyish-black washed with rufous; from the nape (with the outer aspect of the fore-limb) to the lower back silvery-grey, darker towards the neck, brightening towards the tail and front of the thighs, where it is washed with bright yellowish-grey; callosities and outer aspect of the thighs, bright yellow; under surface of the body grey washed with yellow; tail grey at the base, tufted at the tip and yellow; thumb very short. Length of body, 26 inches; of tail, 21 inches.

FEMALE.--Similar to the male, but duller.

YOUNG.--Also paler, with more yellowish-grey round the ears, but the top of the head not black. (_Anderson._)

{140}DISTRIBUTION.--The present species inhabits the forests of the high mountains which clothe the western region of the Principality of Moupin, in North-western China, to Kokonoor and Kansu Kinsu.

HABITS.--This very remarkable animal, whose discovery we owe to the researches of that renowned traveller, the Abbé David, lives in large troops on the highest trees of the forest, in regions where the snow lies throughout the greater part of the year. It feeds on fruits, leaves, and the young shoots of the forest-trees, and of the wild bamboo. It has been placed by some systematists in a separate genus, _Rhinopithecus_, along with _Nasalis larvatus_, from Borneo, on account of the extraordinary form of its nose and of the length of the arm being greater than the fore-arm; but in its structural characters it is very closely related to _Semnopithecus_.

THE NOSED MONKEYS. GENUS NASALIS.

_Nasalis_, Geoffr., Ann. Mus., xix., p. 90 (1812).

This genus contains only one species,

THE PROBOSCIS MONKEY. NASALIS LARVATUS.

(_Plate XXXVII._)

_Cercopithecus larvatus_, Wurmb., Verhand. Bat. Genootsch., iii., p. 145
(1781); Kuhl, Beitr. Zool., p. 12 (1820).

_Simia nasica_, F. Cuv., Dict. Sc. Nat., xx., p. 32 (1821).

_Nasalis larvatus_, Geoffr., Ann. Mus., xix., p. 90 (1812); Lesson, Spec.
des Mamm., p. 66 (1840); Jacq. et Puch., Voy. au Pole Sud, Zool. iii., p.
17, pls. 2, 2A, 2B (1853); Lenz, Zool. Gart., xxxii., p. 216; Gray, Cat.
Monkeys Brit. Mus., p. 13 (1870); Hose, Mamm. Borneo, p. 8 (1893).

PLATE XXXVII.

{141} _Cercopithecus nasicus_, Desmar. et Virey, Nouv. Dict. d'Hist.
Nat., xv., p. 574 (1817); Wagner in Schreb. Säugeth. Suppl. i., p. 102,
pl. x.B (1840).

_Semnopithecus nasicus_, Desmoul., Dict. Class. d'Hist. Nat., vii., p.
570 (1825); Schinz, Syn. Mamm., i., p. 43 (1844); Wagner in Schreb.
Säugeth. Suppl. v., p. 35 (1855).

_Nasalis recurvus_, Vigors et Horsf., Zool. Journ., iv., p. 109 (1828-9;
head of young figured); Martin, P. Z. S., 1837, p. 71.

_Semnopithecus larvatus_, Fischer, Syn. Mamm., p. 16 (1829); Martin,
Mammif. An., p. 453, figs. 279, 280-2 (1841).

_Rhynchopithecus larvatus_, Dahlb., Stud. Zool., p. 93, pl. iv. (1856).

_Semnopithecus_ (_Nasalis_) _larvatus_, Anderson, Zool. Res. Exped.
Yun-nan, p. 42 (1878; with full synonymy).

CHARACTERS.--Face cinnamon-brown; ears blackish, as also the palms and soles; upper surface of the head, neck, back and sides yellowish-brown, conspicuously marked with reddish-brown and white; rump, tail and limbs yellowish-grey; tails of old specimens quite white; sides of face yellow, and a stripe of the same colour on the shoulders. Under surface yellowish-white.

Hair on the head, which is parted down the centre, on the sides of the face, neck and shoulders, long; the chin full-bearded and the tail tufted; ears small; the nose the most conspicuous feature of the face, produced into a proboscis capable of dilatation, with large nostrils opening downwards, separated from each other by a septum of thin cartilage extending to the extremity. In old males the point of the nose reaches quite below the lowest part of the chin; it is pear-shaped, and furrowed down the middle, giving it the {142}appearance of being double tipped; it is widest in the middle of the free portion. The proboscis is fully developed only at an advanced age in both sexes, being much shorter in the young, and turned upwards. Vigors and Horsfield described their _N. recurvus_ from a specimen which appeared to them to be perfectly adult. The forehead is low; the eyes are wide apart, and the neck is short and much dilated from the presence of a very large laryngeal sac. Length of the body, 29½ inches; of the tail, 26 inches.

FEMALE.--Similar to the male, but it is smaller, and wants the greyish rump markings; while the proboscis is somewhat less developed.

YOUNG.--Have the face blackish and the cheeks wrinkled; the back of the head, down to the shoulders and upper part of the fore-limb is dark reddish-brown. "Through a series of changes during which the red-brown of the upper parts first increases in strength, and the grey-brown of the hips and upper side of the tail change to yellowish-white, the adult pelage is reached." (_Anderson._)

This extraordinary animal presents all the structural characters of the genus _Semnopithecus_; but the lower border of the nasal bones, forming the entrance to the nasal chamber, extends considerably below the lower border of the eye-sockets. The facial portion of the skull does not much exceed the brain-case.

The Proboscis Monkey has the sacculated stomach already described in the Langurs.

DISTRIBUTION.--The Proboscis Monkey is confined to the island of Borneo. Mr. Hornaday found it along the west bank of the Sarawak river, both near the sea and two miles below the {143}town. It occurs also in some abundance on the Batang Lupar river. Mr. Hose says that it is chiefly found near the mouths of the rivers in Southern Sarawak.

HABITS.--The Proboscis Monkey, variously called Blanda (or White Man) and "Rasong" by the natives, is an arboreal creature living in small troops. "As usual," writes Mr. Hornaday, "they were over water, and, being swift climbers and quite shy, were hard to kill. I saw altogether, during my ramblings in the forests of Borneo, perhaps a hundred and fifty Proboscis Monkeys, and, without a single exception, all were over water, either river, lake, or submerged forest. As long as they are in sight they are very conspicuous objects, choosing the most commanding positions in open tree-tops. Once I saw thirteen in one tree, sitting lazily on the branches, as is their habit, sunning themselves and enjoying the scenery. It was the finest sight I ever saw in which Monkeys played a part. The cry of the 'Blanda,' is peculiar and unmistakable. Written phonetically it would be 'Honk,' and occasionally 'Kec-honk,' long drawn and deeply resonant, quite like the tone of a bass viol.... The Proboscis Monkey is a large animal of striking appearance both in form and colour. Taken altogether, _Nasalis larvatus_ is, to the hunter-naturalist, a very striking object of pursuit, and were he not partially eclipsed by the Orang he would be the most famous Quadrumane in the East Indies."

THE MAN-LIKE APES. FAMILY SIMIIDÆ.

In this family are included the Gibbons, the Orangs, the Gorillas, and the Chimpanzees, the most highly organised and the nearest to Man in structure of all the _Anthropoidea_. To {144}these groups the term "Ape," has been by many writers chiefly restricted, the remaining families of the Old World, and all of the Western Hemisphere, being designated "Monkeys" as a convenient method of nomenclature. The outward resemblance of the _Simiidæ_ to Man has made the various members of the family objects of the greatest interest, not alone to the naturalist, but to every intelligent person; and has naturally suggested a constant inter-comparison between the characters of both.

They are all essentially arboreal climbing animals, yet when they come to the ground they progress in a semi-erect position of their own accord. Their front-limbs are always so much longer than their hind-limbs, that when walking on a level surface their fingers reach the ground, without stooping lower than their semi-erect attitude. Their front-limbs vary in length in the different genera; so does the thumb; but their great-toe is always smaller in proportion to the foot than it is in Man, and, unlike his, is opposable to the other toes. As they belong to the Catarrhine group, their nose has a narrow partition between the nostrils, which are directed downwards. In all, an external tail, cheek-pouches, and (except among the Gibbons) ischial callosities are wanting. All are covered with hair, some more thickly than others, but no Ape has on its head the long abundant locks which Man possesses.

The form of the skull varies very greatly in the _Simiidæ_. It is, however, always longer than broad. In its frontal region it is never so rounded and elevated as in Man. The roof of the eye-sockets projects into the fore part of the brain-cavity, and considerably reduces its capacity. The pre-maxillary bones (carrying the incisor teeth) are relatively more distinct and much larger than in Man, "the sutures {145}separating them from the maxillary bones remaining visible after the adult dentition has been obtained." (_Mivart._)[1] The _Simiidæ_ have a bony meatus or canal to the ear. The back part of the head, which among the Guenons is flat, is convex among the _Simiidæ_. The palate is long and narrow, and the margins of the jaws nearly parallel. The lower jaw is always in one piece, the two halves being firmly ossified in the middle. The dental formula of the Man-like Apes is I2/2, C1/1, P2/2, M3/3 (_i.e._, 32 teeth in all); their inner upper incisors are larger, and the lower are smaller than the outer pair; the canines are large, and between them and the neighbouring incisor above there is a vacuity (or diastema), and, below, between them and the nearest pre-molar. The upper pre-molars have three roots, and the lower, two; the upper molars have four tubercles, their crowns being relatively wide; the lower molars have five tubercles, but the posterior has no hind talon.

The opening for the passage of the spinal cord is situated towards the posterior portion of the base of the cranium, and is thus further from the centre than in Man.

Except among the Gibbons, the vertebral column shows in the sacral region indications of that curve--or concavity in the back between the two convexities of the neck and loins--which is one of the distinctive characters of the human skeleton. The processes for the interlocking of the vertebræ, which are large in the lower Anthropoids, are much reduced in the Man-like Apes, and become inconspicuous in Man.

The breast-bone is flat, and resembles that of Man, and, in all, except the Orang, is composed of two bones. The {146}arm-bone is often shorter than the fore-arm. The _radius_ and _ulna_ can be completely rotated. The articulating surface of the _trapezium_, the wrist-bone (_carpus_), to which the thumb is attached, has a rounded face like that of the _ento-cuneiform_ bone in the ankle (_tarsus_), a form which, as already pointed out (Vol. I., p. 11), was in the Lemuroids correlated with an opposable great-toe, so here it is correlated with a true opposable thumb. In the Monkeys and Lemuroids this bone is not generally rounded, and they have not the thumb opposable in the strict sense that it is among the higher Apes.

The thigh-bone (_femur_) is shorter than the arm-bone (_humerus_); and the foot is very long; yet the absolute length of the _tarsus_ is never so great as in Man; it is the rest of the foot which is so much longer relatively in Apes. The _ento-cuneiform_, or articulating bone of the ankle for the great-toe, has a sub-cylindrical surface, which gives a great range of motion to that digit, towards and from the plane of the foot.

The brain of the Apes closely resembles in general form and structure that of Man; but the cerebral hemispheres differ in being much elongated and depressed, and the cranial capacity of the skull, which is never less than 55 cubic inches in any normal human subject, is in the Chimpanzee 27½ cubic inches; in the Gorilla 35 inches; in the Orang 26 inches; and in the Gibbons very much less. The cerebrum has its surface richly convoluted; and its posterior lobes always entirely over-arching the cerebellum, except in the Siamang (_Hylobates syndactylus_).

"As to the convolutions, the brains of the Apes exhibit every stage of progress, from the almost smooth brain of the Marmoset, to the Orang and the Chimpanzee, which fall but little below Man. And it is most remarkable that as soon as {147}all the principal sulci [or grooves] appear, the pattern according to which they are arranged is identical with that of the corresponding sulci of Man. The surface of the brain of a Monkey exhibits a sort of skeleton map of Man's, and in the Man-like Apes the details become more and more filled in, until it is only in minor characters, such as the greater excavation of the anterior lobes, the constant presence of fissures usually absent in Man, and the different disposition and proportions of some convolutions, that the Chimpanzee's or the Orang's brain can be structurally distinguished from Man's.... And the difference between the brains of the Chimpanzee and of Man is almost insignificant when compared with that between the Chimpanzee's brain and that of a Lemur." (_Huxley._)

The Anthropoid Apes have no cheek-pouches. The larynx has large dilatations of the shallow depressions--called ventricles--of the mucous membrane on each side of its inner surface--which may extend down as far as the arm-pits, and be connected with powerful voice possessed in most of the species. The stomach is simple, like that of Man, and not sacculated, as in the last family (the _Cercopithecidæ_).

The uterus and other structures connected with the reproductive system resemble those in the human subject. The length of gestation varies probably in the different genera, and is unknown in many of the species. The period for which the young are suckled by the mother lasts about six months. "The proportions of the limbs to one another and to the body do not sensibly change after birth; but the body, limbs, and jaws enlarge to a much greater extent than the brain-case." (_Huxley._) Observations are still required, in regard to most of the species, as to the age at which they arrive at maturity, and are able to reproduce.

{148}The _Simiidæ_--the most intelligent of the animal kingdom--are all diurnal animals, and essentially arboreal. Many of the members of the family have, when walking, a tendency to tread on the outer edge of the foot, turning, therefore, the toe inward on account of the free motion which is possible between the various bones of its ankle, whereas, in the human foot, these bones are more solidly bound together. When climbing, the power of turning in the sole is, as is evident, of the greatest advantage to the Ape. Their food is chiefly vegetable; a few species exhibit slight carnivorous tendencies.

"Of the various genera of the _Simiidæ_, the Gibbons are most remote from Man. The Orangs come nearest in the number of the ribs, the form of the cerebral hemispheres, and certain other characters of the brain and skull; but they differ from him much more widely in other characters, especially in the limbs, than the Gorilla and the Chimpanzee do. Of the Chimpanzees the Gorilla is more Man-like in the proportions of the leg to the body, and of the foot to the hand; and likewise in the size of the heel, the curvature of the spine, and the absolute capacity of the cranium. The true Chimpanzees approach Man most closely in the skull, dentition, and proportionate length of the arms." (_Huxley._)

The _Simiidæ_ are confined to the Ethiopian and Indian Regions. The Gorillas and Chimpanzees live exclusively in the Tropical Regions of Western and Central Africa; the Gibbons range into all the four provinces of the Indian Region; while the Orangs are confined to two islands of the Indo-Malayan Sub-region.

THE GIBBONS. GENUS HYLOBATES.

_Hylobates_, Illiger, Prodr. Syst. Mamm., p. 67 (1811).

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._)