The Woolly Monkeys differ from the preceding genera by the presence of a well developed pollex. They resemble Eriodes in their fur and compressed nails, but differ in the more widely separated nares. The tail resembles that of the preceding genera. Speaking of these Monkeys Mr. Bates observes that “the Barrigudos are very bulky animals, whilst the Spider Monkeys are remarkable for the slenderness of their bodies and limbs. I obtained specimens of what have been considered two species, one (L. olivaceus?) having the head clothed with gray, the other (L. humboldti, Fig. 342) with black fur. They both live together in the same places, and are probably only differently coloured individuals of one and the same species. I sent home a very large male of one of these kinds, which measured 27 inches in length of trunk, the tail being 26 inches long; it was the largest monkey I saw in America, with the exception of a black Howler, whose body was 28 inches in height. The skin of the face in the Barrigudo is black and wrinkled, the forehead is low, with the eyebrows projecting.... In the forests the Barrigudo is not a very active animal; it lives exclusively on fruits, and is much persecuted by the Indians on account of the excellence of its flesh as food.” Five species are usually recognised, viz. L. canus, L. humboldti, L. castelnaui, L. tschudii, and L. geoffroyi.

Cebus.[675]—Form rather robust; limbs moderate; fur not woolly; pollex well developed; tail not naked beneath distally.

This, the typical, genus includes the Sapajous or Capuchins (Fig. 343), which are so commonly seen in this country in captivity, being the favourite Monkeys of itinerant musicians. They are smaller and stouter in build than the Spider Monkeys, from which they are readily distinguished by the well-developed pollex, and the absence of a naked under surface to the extremity of the tail. At least twenty species have been described (C. fatuellus, C. lunatus, C. capucinus, C. albifrons, C. hypoleucus, etc.), but it is probable that some of these are not entitled to stand, since there is a large amount of individual variation. Fossil remains of species of Cebus have been described from the Pleistocene cavern-deposits of Brazil.

Family Cercopithecidæ.

Dentition: i ²⁄₂, c ¹⁄₁, p ²⁄₂, m ³⁄₃; total 32. Crowns of molars elongated antero-posteriorly, with the tubercles forming a pair of imperfect transverse ridges, and the last lower molar usually with a hind talon. A bony external auditory meatus. A narrow internarial septum. Tail non-prehensile. Ischiatic callosities present. Cheek-pouches present or absent. Pollex, when present, opposable. Pelvic limbs never much longer than pectoral. Sternum narrow. Cæcum without vermiform appendage.

This family includes all the Old World Apes, with the exception of the Simiidæ, and may be divided into the subfamilies Cercopithecinæ and Semnopithecinæ.

Subfamily Cercopithecinæ.—Pelvic and pectoral limbs approximately equal; tail variable; cheek-pouches present; stomach simple.

This subfamily comprises, the African Baboons, the common Indian Monkeys constituting the genus Macacus, together with the African Cercopithecus and Cercocebus and a few allied types.

Cynocephalus.[676]—Muzzle much elongated (Fig. 344), with the nostrils terminal; ischial callosities very large; tail more or less short; muzzle swollen by enlargement of the maxillæ. Now confined to Africa and Arabia.

This genus comprises the typical Baboons, and we may select the well-known Mandrill (C. maimon), of tropical West Africa, as a good illustrative example. It may be mentioned in passing that the name Mandrill appears to have been first introduced into English literature by William Smith in his New Voyage to Guinea, published in 1744, wherein he mentions among the animals of Sierra Leone one “called by the white men in this country Mandrill,” but adds, “why it is so called I know not.”[677] Smith gives sufficiently accurate details to show that his animal is not that now called Mandrill, but the Chimpanzee. Buffon, however, while quoting Smith’s description, transferred the name to the very different species now under consideration, and to that it has been attached ever since.

The Baboons generally are distinguished from most other Monkeys by the comparative equality of the length of their limbs, which with the structure of the vertebral column adapts them rather for quadrupedal progression on the ground than for climbing among the branches of trees; and some of them, like the South African Chacma (C. porcarius), of which the skeleton is shown in Fig. 344, live habitually among rocks, and are much less completely frugivorous than other Apes. They are also remarkable for the great size of their face and jaws as compared with the part of the skull which encloses the brain. The Mandrill, in addition to these characters, is distinguished by the heaviness of its body, stoutness and strength of its limbs, and exceeding shortness of its tail, which is a mere stump, not 2 inches long, and usually carried erect. It is, moreover, remarkable for the prominence of its brow ridges, beneath which the small and closely approximated eyes are deeply sunk; the immense size of the canine teeth; the great development of a pair of oval bony prominences on the maxillary bones in front of the orbits, rising on each side of the median line of the face, and covered by a longitudinally ribbed naked skin; and more especially for the extraordinarily vivid colouring of some parts of the skin. The body generally is covered with a full soft coating of hair of a light olive-brown above and silvery-gray beneath, and the chin is furnished underneath with a small pointed yellow beard. The hair of the forehead and temples is directed upwards so as to meet in a point on the crown, which gives the head a triangular appearance. The ears are naked and of a bluish-black colour. The hands and feet are naked and black. A large space around the greatly developed ischial callosities, as well as the upper part of the insides of the thighs, are naked and of a crimson colour, shading off on the sides to lilac or blue, which, depending not upon pigment but upon injection of the superficial blood-vessels, varies in intensity according to the condition of the animal—increasing under excitement, fading during sickness, and disappearing after death. But it is in the face that the most remarkable disposition of vivid hues occur, more resembling those of a brilliantly coloured flower than what might be expected in the cutaneous covering of a mammal. The cheek-prominences are of an intense blue, the effect of which is heightened by deeply sunk longitudinal furrows of a darker tint, while the central line and termination of the nose are a bright scarlet. Notwithstanding the beauty of these colours in themselves, the whole combination, with the form and expression of features, quite justifies Cuvier’s assertion that “il serait difficile de se figurer un être plus hideux que le Mandrill.”

It is only to fully adult males that this description applies. The female is of much smaller size, and of more slender make; and, though the general tone of the hairy parts of the body is the same, the prominences, furrows, and colouring of the face are very much less marked. The young males have black faces. At the age of three the blue of the cheeks begins to appear, but it is not until they are about five, when they cut their great canine teeth, that they acquire the characteristic red of the end of the nose.

The Mandrills, especially the old males, are remarkable for the ferocity of their disposition, as well as for other disagreeable qualities, which are fully described in Cuvier’s account of the animal in La Ménagerie du Muséum d’Histoire Naturelle (1801), but when young they can easily be tamed. Like the rest of the Baboons, they appear to be rather indiscriminate eaters, feeding upon fruit, roots, reptiles, insects, scorpions, etc., and inhabit open rocky ground rather than forests. Not much is known of the Mandrill’s habits in the wild state, nor of the exact limits of its geographical distribution. The specimens brought to Europe all come from the west coast of tropical Africa, from Guinea to the Gaboon.

An allied species, the Drill (C. leucophæus), which resembles the Mandrill in size, general proportions, and shortness of tail, but wants the bright colouring of the face which makes that animal so remarkable, inhabits the same district. Other well-known species are the Yellow Baboon (C. babuin), of West Africa (Fig. 345); the Arabian Baboon (C. hamadryas), of Arabia and Abyssinia; and the Anubis Baboon (C. anubis), of West Africa.

It is very noteworthy from a distributional point of view, as showing the former intimate connection between the faunas of the Oriental and Ethiopian regions, that fossil remains of Baboons have been found in the Pleistocene cavern-deposits of Madras, and also in the older Pliocene beds of the Siwalik Hills in Northern India; the two species from the latter deposits having been described as C. subhimalayanus and C. falconeri.

Theropithecus.[678]—Distinguished from Cynocephalus by the nostrils not being terminal, but situated as in Macacus. This genus is represented by the Abyssinian Gelada (T. gelada) and the allied T. obscurus.

Cynopithecus.[679]—The Black Ape of Celebes (C. niger) forms a connecting link between the Baboons and the genus Macacus; the skull differing from that of the latter in the development of longitudinal ridges on the sides of the upper surface of the maxillæ, as in some of the species of Cynocephalus. The muzzle is also more produced than in Macacus.

Macacus.[680]—Muzzle considerably produced; nostrils not terminal; cheek-pouches and ischial callosities well developed; tail long, short, or absent; a distinct talon to the third lower molar.

With the exception of the Barbary Ape (M. inuus) of Northern Africa and Gibraltar, the Macaques are now exclusively Asiatic, one species (Fig. 346) occurring in Tibet, and another (M. speciosus) being found in Japan. All these Monkeys are of stout build, and it is chiefly by the greater production of the muzzle, the larger ischiatic callosities, and the frequent shortness of the tail that they are distinguished from the under-mentioned African genera. The transition from the longer-tailed to the short-tailed forms is so complete that the proposed generic separation of the latter as Innus is impracticable. In M. innus the tail is wanting; in M. tibetanus (Fig. 346) and M. nemestrinus of Tenasserim it is short; in the common Bengal Monkey (M. rhesus) it is about one-half the length of the head and body, while in M. cynomolgus and its allies it is still longer. In the Indian Lion-tailed Monkey (M. silenus) it is tufted at the end.

The following summary of the habits of the Macaques is taken from Mr. W. T. Blanford’s Mammals of British India: “The species of the present genus resemble each other in their habits; they are found in flocks, often of considerable size, and generally composed of individuals of both sexes and of all ages. They are active animals, though less rapid in their movements, whether on trees or on the ground than the Semnopitheci. Their food is varied, most of the species, if not all, eating insects as well as seeds, fruits, etc., and one kind feeding partly on crustacea. They have occasionally been known to devour lizards, and, it is said, frogs also. All have the habit of cramming food into their cheek-pouches for mastication at leisure—a practice that must be familiar to any one who has fed monkeys in confinement. The voice and gestures of all the species are similar, and differ entirely from those of both the Gibbons and Semnopitheci.... The majority of the species are very docile when young. They thrive well, and several of them have bred in confinement. The period of gestation is almost seven months, only a single young one, as a rule, being produced at a birth. They become adult at the age of four or five years, but breed earlier.”

The Common Indian M. rhesus is found in the Himalaya at an elevation of over 8000 feet.

Fossil remains of Macacus are found in India in the Pleistocene of Madras and the Pliocene of the Punjab; and they also occur in the Pliocene of France and Italy, those from the latter deposits having been incorrectly separated as Aulaxinuus. Part of the jaw of a Monkey from the Pleistocene of Essex has been described as Macacus pliocenus, and is very interesting as showing the presence of Apes in Europe at that late period.

Cercocebus.[681]—An African genus agreeing with Macacus in the presence of a hind talon to the third lower molar, but with the other characters of Cercopithecus. The species of this genus are known as Mangabeys, or White-eyelid Monkeys, and include C. collaris, C. fuliginosus, C. æthiops, and C. albigena; all being from West Africa.

Cercopithecus.[682]—Muzzle more or less short; ischial callosities moderate; tail long; no talon to third lower molar. Build more slender than in Macacus. Confined to Africa.

The members of this and the last genus include those Monkeys which in their comparative slender build and length of tail make the nearest approach to the next subfamily. There are numerous species, among which the Green Monkey (C. cullitrichus), the Grivet (C. griseo-viridis), the Vervet (C. lalandi), the Pluto Monkey (C. pluto, Fig. 347). The Patas (C. ruber), the Diana Monkey (C. diana), and the Mona Monkey (C. mona) are well-known types.

Subfamily Semnopithecinæ.[683]—Pelvic limbs longer than the pectoral, tail very long; no cheek-pouches; stomach sacculated. Build slender.

This subfamily is represented by three genera, of which one is African and two are Asiatic. Mr. W. T. Blanford, in his Mammals of British India, observes that “the members of this subfamily are readily distinguished by their slender form, and by the absence of cheek-pouches. They are more purely herbivorous than the Macaque Monkeys, and a considerable portion of their food consists of leaves and young shoots. In consequence probably of the nature of their food, these Monkeys are more delicate than the species of Macacus, and are thus less easily kept in captivity. They are consequently far less well represented in European museums, and have been less studied by European naturalists. Very little is known of their general life-history or of their feeding habits.”

Their digestive organs are much modified, the stomach attaining an extraordinary complexity, which may be described as follows. An ordinary stomach must be supposed to lie immensely elongated, and gradually tapering from the cardiac end to a very prolonged, narrow, pyloric extremity. Then two longitudinal muscular bands, corresponding in situation to the greater and lesser curvatures of an ordinary stomach—the former commencing just below the fundus, and the latter at the cardiac orifice, and both proceeding towards the pylorus—are developed, so as to pucker up the cavity into a number of pouches, exactly in the same principle as the human colon is puckered up by its three longitudinal bands. These pouches are largest and most strongly marked at the œsophageal end, and becoming less and less distinct, quite cease several inches before the pylorus is reached, the last part of the organ being a simple smooth-walled tube. The fundus, or cardiac end of the stomach, is formed by a single large sac, slightly constricted on its under surface by the prolongation of the interior longitudinal band, or that corresponding to the great curvature. The œsophagus enters into the upper part of the left, or pyloric end of this sac, or rather at the point of junction between it and the second (also a very large) sacculus. Furthermore, the whole of this elongated sacculated organ is, by the brevity, as it were, of the lesser curvature, coiled upon itself in an irregularly spiral manner, so that when in situ the pylorus comes to be placed very near the œsophageal entrance.

Nasalis.[684]—Skull resembling that of the Cercopithecinæ in that the lower border of the nasal bones extends considerably below the lower border of the orbits, whereas in the other Semnopithecinæ the aperture of the nares extends upwards between the orbits. Nose produced into a large proboscis. Other characters as in Semnopithecus.

This genus includes only the Proboscis Monkey (N. larratus) of Borneo, remarkable for the great prolongation of the nose in the adult. In young animals the nose is relatively much shorter, and bent upwards after the manner of that of Semnopithecus roxellanæ (Fig. 349).

Semnopithecus.[685]—Pollex small; narial aperture extending upwards between the orbits. Now confined to Asia.

This genus is characteristic of South-Eastern Asia from the Himalaya southwards, the Oriental region being its headquarters. The development of the muzzle is less than in the Macaques, and the facial angle is higher, but it does not appear that this indicates greater intellectual capacity. The outlying S. roxellanæ[686] (Fig. 349), of the highlands of Eastern Tibet and Kansu, is remarkable for the peculiar upturned nose, in which respect, as already mentioned, it recalls the young of Nasalis larvatus. The genus is represented in India and Burma by no less than fourteen species, of which the common Indian Langur, or Hanuman Monkey (S. entellus) and the larger Himalayan Langur (S. schistaceus) are two of the best known. In the former the length of the head and body is about 24, and that of the tail 38 inches in adult males. This monkey, owing to the veneration in which it is held by the Hindus, is a great pest in many parts of India, frequently pilfering grain from the shops in the native bazaars. According to Mr. Blanford, it “is usually found in smaller or larger communities, composed of individuals of both sexes and of all ages, the youngest clinging to their mothers and being carried by them, especially when alarmed. An old male is occasionally found solitary, as with so many other mammals.... Apart from villages, the high trees on the banks of streams or of tanks, and, in parts of Central India, rocky hills are the favourite haunts of these monkeys. Whether on trees, on rocks, or on the ground, they are exceedingly active.” The closely allied S. schistaceus attains a larger average size, full grown males attaining a length of 30 inches, the tail measuring 36 inches. In the spring and winter this species may be observed in the Kashmir Himalaya leaping among the snow-laden trees of the forest. In a fossil state Semnopithecus occurs in the Pleistocene and Pliocene of India, and it has also been recorded from the Pliocene of France and Italy.

Colobus.[687]—This African genus differs from Semnopithecus in that the pollex is absent or reduced to a small tubercle, which may or may not carry a nail. About eleven species have been described, some of which are remarkable for the beautiful mantle of long silky hair which hangs down from each side of the body, and for their tufted tails. In C. guereza from Abyssinia these are white, and the rest of the body and limbs black. Others (as C. satanas) are entirely black. The skins of the long-haired species are largely imported into Europe for the manufacture of ladies’ muffs, etc.

Extinct Genera.—Certain types of Apes from the European Tertiaries indicate genera referable to the Cercopithecidæ, but distinct from any of those now living. Of these Mesopithecus,[688] from the Lower Pliocene Pikermi beds of Attica, is known by almost complete skeletons, and resembles Macacus in the shortness and stoutness of the limbs, but agrees with Semnopithecus in the characters of the skull and teeth. An allied Monkey from the Lower Pliocene of Perpignan, in France, differs from Mesopithecus pentelici by its superior size, proportionately more produced muzzle, and larger hind talon to the last lower molar; it has been described under the name of Dolichopithecus.[689]

The genus Oreopithecus[690] was founded upon the remains of an Ape from the Middle Miocene of Monte Bamboli, in Tuscany, of somewhat larger size than a Gibbon, and apparently presenting characters connecting the Cercopithecidæ and Simiidæ. According to Dr. Ristori,[691] it resembles the former, especially Cynocephalus and Semnopithecus, in the long dental series and the elongation of the last molars; but in the shortness of the face, rounding of the chin, and the diagonal arrangement of the molar tubercles, it approximates to the Simiidæ, of which it may have been an ancestral type.

Family Simiidæ.

Crowns of molars relatively wide, with the angles more or less rounded off, the tubercles not forming transverse ridges, and the last lower molar without a hind talon. No tail. No cheek-pouches. Ischiatic callosities, if present, small. Pectoral limbs much longer than pelvic. Sternum broad. Cæcum with vermiform appendage. Centrale of carpus sometimes absent. Other characters as in Cercopithecidæ.

This family contains the true Anthropoid Old World Apes, namely the Gibbons, Orangs, Chimpanzees, and Gorillas, which are the most highly organised of all the Apes, and thus make the nearest approach to Man.

Hylobates.[692]—Skull not produced at the vertex; body and limbs slender, the pectoral limbs being so elongated that the hands reach the ground when walking upright; hallux well developed; a centrale in the carpus; and small ischiatic callosities. Size smaller than in the following genera, the height of the largest species (H. syndactylus) not much exceeding 3 feet. Now confined to Asia.

The Gibbons, or Long-armed Apes (Figs. 350, 351), are readily distinguished from the remaining members of the family by the characters given above, as well as by the circumstance that they are the only Apes which habitually walk in an upright position. It is in these animals that we meet with the last traces of the ischial callosities so largely developed in the Cercopithecidæ. The species are now restricted to South-Eastern Asia, being especially abundant in the Malay Archipelago and adjacent regions.

The largest species is the Sumatran Siamang (H. syndactylus), which attains a height of 3 feet, and has been generically separated by some writers as Siamanga. It is remarkable as having a better developed chin and wider sternum than any other Ape, and differs from the other members of the genus by the circumstance that the second and third digits of the pes are united by skin as far as their last joints. Exclusive of this species, the Gibbons differ but little from one another in size and general conformation, and since the colour of individuals undoubtedly referable to a single species is remarkably variable, there is much uncertainty about the number of species, and much confusion in the nomenclature. Among well-marked species we may mention the Hoolock (H. hoolock), ranging from the South of Assam through Sylhet and Cachar to the Irawadi Valley near Bhamo, the White-handed Gibbon (H. lar, Fig. 350), which is found in Tenasserim and throughout Malayana, the Dun-coloured Gibbon (H. entelloides, Fig. 351) of Malayana, and the Tufted Gibbon (H. pileatus) of Siam and Cambogia.

The following account of the habits of the Gibbons is taken from Mr. W. T. Blanford’s Mammals of British India. “Gibbons are thoroughly arboreal, and Hoolocks are almost, if not entirely, confined to hill-forest. 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 hillsides 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 swing downwards. They also ascend with great rapidity, swinging themselves from tree to tree. 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. The arms are usually held upwards, sometimes horizontally, their great length giving the animal a very peculiar aspect. Gibbons walk rather quickly, with a waddling gait, and can easily be overtaken by men when on the ground. The food of these Apes consists of fruit, leaves, young shoots, spiders (of which they are very fond), insects, birds’ eggs, and almost certainly of young birds, if not of any birds they can capture. Anderson found that small birds were killed and devoured by Hoolocks in confinement with a method and eagerness that showed this prey to be the natural food of the Apes. The Hoolock drinks with its lips, putting its head down to the water as Monkeys do. All species of Hylobates have a powerful voice, and the common name of the Hoolock is taken from its peculiar double call, which is repeated several times. At a distance the sound much resembles a human voice; it is a peculiar wailing note, audible from afar, and in the countries inhabited by these animals is one of the most familiar forest sounds. The calls commence at daybreak, and are continued till 9 or 10 A.M., several of the flock joining in the cry, like hounds giving tongue. After 9 or 10 o’clock in the morning the animals feed or rest, and remain silent throughout the middle of the day, but recommence calling towards evening, though to a less extent than in the earlier part of the day.”

The skull of the Gibbons, although agreeing with that of other Apes in its prognathism, presents a somewhat human appearance, and the molar teeth are also very like diminutive human molars. In the anterior inward inclination of the two series of cheek-teeth and the inward position of the upper premolars the Gibbons make an approach to the human type unknown in other Apes.

The figure of the liver of one species of this genus is introduced to show the general absence of lateral fissures and the small size of the caudate lobe (c) characteristic of the liver of all the Simiidæ, except Gorilla (see p. 706), as well as that of Man. Another specimen of the liver of the same species showed scarcely any trace of a caudate lobe.

A fossil Ape from the Middle Miocene of France, originally described as Pliopithecus, indicates an extinct Gibbon which does not appear to be generically separable from Hylobates.

Simia.[693]—Skull (Fig. 353) produced at the vertex; body and limbs massive; the pectoral limbs reaching to the ankle; a centrale in the carpus; hallux very small; sixteen dorso-lumbar vertebræ, and twelve pairs of ribs; no ischiatic callosities. Oriental.

This genus includes the large red-haired Apes from Sumatra and Borneo commonly known as Orangs, or Orang-Utans,[694] of which there is probably only a single species (S. satyrus). These animals inhabit the swampy forests near the coasts; and the males attain a height of about 4 feet 4 inches. The body is very bulky and the legs exceedingly short, but the arms are very long, reaching in the erect posture down to the ankles. The Orang walks resting on the knuckles of the hands and the outer sides of the feet, with the soles of the latter turned mainly inwards, as in Fig. 354. Its movements appear to be slow and deliberate, and in those specimens which have been kept in captivity in this country the demeanour is languid and melancholy, although this is far from being the case with those shown in the more congenial climate of the Zoological Gardens at Calcutta. The habits of these animals are arboreal, and they build a kind of shelter or nest of boughs and leaves; their food appears to consist mainly of fruits, and is exclusively of a vegetable nature. The whole of the body is clothed with long hair of a reddish-brown colour, and full-grown males have a well developed beard; the males not unfrequently also develop a large warty protuberance, formed of fibro-cellular tissue, on either side of the face. The hands are long, and are characterised by the small size of the pollex, which does not reach to the end of the metacarpal of the index finger. The feet have a similar structure, the hallux only reaching to the middle of the proximal phalange of the adjacent toe, and being often destitute not only of a nail, but likewise of the terminal phalange. The presence of a centrale in the carpus is a feature in which Simia agrees with Hylobates and the lower Apes, and differs from the two following genera and Man. With very rare exceptions the number of dorso-lumbar vertebræ is sixteen, of which twelve carry ribs, and therefore belong to the dorsal series, while the remaining four are lumbar. The distinction between the last lumbar and the first sacral vertebræ is clearly marked in young skeletons by the additional pleurapophysial ossifications (sacral ribs) in the transverse processes of the latter. Thus though Simia presents a closer resemblance to Man than does Anthropopithecus in the number of ribs, it differs in the more important characters of that of the whole series of trunk-vertebræ.[695] The hemispheres of the brain are much convoluted; the whole brain being more human-like than in any other Ape. The larynx is remarkable for having a prolongation from each ventricle, which in the adult become of enormous dimensions, and unite in front of the trachea to form one large sac extending downwards between the muscles to the axilla.

The skull of the Orang (Fig. 353) is characterised by its highly vaulted cranial portion, which is comparatively short (brachycephalic). The sagittal crest is well developed on the vertex, and has a highly convex contour; the superciliary ridges are but moderately developed, and do not stand out in the prominent manner so characteristic of the Gorilla. The aperture of the nares in the skull is more pear-shaped than in the two following genera.

The canines of the male Orang attain a great development; and the molars are characterised by the complex structure of their cusps and the numerous rugosities on the crown surface. The outer border of the upper premolars is placed in the same line as that of the molars.

The broken canine tooth of a large Anthropoid Ape from the Lower Pliocene of the Siwalik Hills probably indicates the existence at that period of a species of Simia in Northern India.

Gorilla.[696]—Skull not produced at the vertex; body and limbs massive, the pectoral limb not reaching below the middle of the lower leg (Fig. 355); no centrale in the carpus: hallux well developed; seventeen dorso-lumbar vertebræ, of which thirteen carry ribs; no ischiatic callosities. Male much larger than female, and with very strongly marked cranial ridges, which are wanting in the latter. Mandibular symphysis long. Ethiopian.

The well-known Gorilla (Fig. 356), of which there seems to be only one species (G. savagei), is found in Western Equatorial Africa, chiefly or entirely in the district enclosed by the Cameroon and Congo rivers. It is the largest of all the Apes, its bulk considerably exceeding that of man, although from the shortness of the legs it appears never to attain a greater height than 5½ feet. The first introduction of this animal to the notice of zoologists was made in 1847 by Dr. Thomas Savage, but it was not fully known till many years later.

The skin of the Gorilla is entirely black, the hair being blackish, but turning more or less gray in old individuals. The arms reach down as far as the middle of the lower leg; while the pollex extends only a short distance beyond the base of the first phalange of the index finger, and the hallux reaches nearly as far as the distal extremity of the corresponding digit of the foot. The digits of both the hand and foot are united together by integument as far as the distal extremities of the first phalanges. The larynx has very capacious air-sacs, which meet in front of the trachea and communicate with the ventricles; and in advanced age these sacs may extend to the axilla. The ears are relatively small. The skull is of an elongated or dolichocephalic type; that of the adult male being characterised by the enormous development of the supraorbital ridges, which form a kind of penthouse over the eyes, and contribute to the peculiarly ferocious appearance of the animal. The sagittal crest is also very large. The canine teeth of the male are very large, and are inclined outwards in both jaws. In the cheek-teeth the upper premolars are of considerable antero-posterior extent, with their outer border placed in the same line as that of the molars; and the third upper molar is larger than either of the others.

The posterior cervical vertebræ are characterised by the great height of their neural spines, which thus form a strong basis for the powerful cervical muscles supporting the massive skull. In some instances the fourth lumbar vertebra becomes ankylosed to the sacrum, as is occasionally found to be the case in some of the lower human races.

In the absence of a centrale to the carpus, and also in the number of the dorso-lumbar vertebræ, the present and following genus resemble man; although they both differ in having thirteen in place of twelve pairs of ribs.

The brain of the Gorilla, according to Dr. Hartmann, resembles that of the Orang in the complexity of its convolutions, and is thereby distinguished from that of the Chimpanzee. In form it is of the long oval characteristic of Man; the brain of the Chimpanzee and Orang being more rounded.

Gorillas live in family parties in the depths of the dense forests of Western Equatorial Africa, seeking their food during the day, while at night it is said that the female and young ascend a tree at the foot of which the male sleeps. They walk with the backs of their closed hands and the flat soles of the feet placed on the ground. Although there has been much exaggeration on this point, it appears certain that the male Gorilla is an extremely ferocious and dangerous animal when brought to bay, but the statements as to its making unprovoked assaults on men do not appear authentic. They utter deep guttural sounds, which on some occasions may be described as grunts and at others as a roar.

Anthropopithecus.[697]—One of the most important differences of this genus from the preceding is the absence of any marked disparity between the two sexes, either in the size or the conformation of the skull, although the male can always be distinguished by the larger size of the canine teeth. The mandibular symphysis is also much shorter. Differences in the characters of the teeth are described below. The genus is confined at the present day to the Ethiopian region.

The Chimpanzees (Fig. 357) inhabit Western and Central Equatorial Africa; and there has been much discussion whether they should all be included under one specific name (A. troglodytes), or whether there are really two or more species. A female specimen now living in the London Zoological Gardens, characterised among other distinctive features by the nearly bald head, clearly indicates, however, a second species, which probably corresponds to the imperfectly defined A. calvus of Du Chaillu.

The region inhabited by the Chimpanzees extends from the Gambia to the Benguela, reaching as far inland as 28° E. long. The Common Chimpanzee is a smaller animal than the Gorilla, its height not exceeding 5 feet. In colour it is darker than the latter, and the ears are relatively larger. In the upright position the arms reach only a short distance below the knee, in which respect the Chimpanzee is more human-like than any of the other Apes. The face is furnished with distinct whiskers, eyebrows, and eyelashes. The pollex reaches nearly or quite to the base of the first phalange of the index finger, and the hallux to the base of the second phalange of the corresponding digit of the foot. The laryngeal sacs are as largely developed as in the Gorilla.