Chapter XIV: The Order Primates (2)

The sacrum is longest in the _Simiidæ_ and Man, its greatest absolute length occurring in the Gorilla, and the relative greatest length being found in _Hylobates_. The _Simiidæ_ never have less than five, and may have six sacral vertebræ; while in the lower forms there are generally only two or three, although occasionally four in some of the American forms. The Orang and some of the Baboons make the nearest approximation to Man in the marked angle formed at the junction of the sacrum with the lumbar vertebræ. Except in the _Simiidæ_ and _Macacus inuus_, the number of caudal vertebræ in the Apes always exceeds four, but they may be reduced to five in the Mandrill (_Cynocephalus maimon_). In _Macacus_ and _Uacaria_ the shortness of the tail is attained by the small size of the vertebræ themselves, the number of which may be from fifteen to seventeen. Other forms usually have from twenty to thirty-three caudals, the latter number occurring in _Ateles_ (Fig. 335), where the tail is relatively the longest. The tail is, however, absolutely longest in _Semnopithecus_, _Colobus_, and their allies, the length being partly due to the size of the component vertebræ. Chevron bones are present in all forms having a distinct tail; and, together with other processes for muscular attachment, attain their greatest development in _Ateles_.

The vertebral processes known as metapophyses and anapophyses, which are generally inconspicuous in Man, and are but small in the _Simiidæ_, attain a large development in the lower forms. The metapophyses generally commence in the eighth or ninth dorsal, and continue to the anterior caudals, where they gradually merge in the prezygapophyses. The anapophyses, which are most developed in the _Cebidæ_, project outwards and backwards from one vertebra to embrace the prezygapophyses of the succeeding one. They occur generally in the same region as the metapophyses, but usually cease at the penultimate lumbar, although in some cases they can be traced on to the posterior cervicals and anterior caudals, in the latter region passing into the transverse processes.

In most Apes the sternum is narrow, and consists of a more or less enlarged manubrium, followed by a chain of subequal and antero-posteriorly elongated bones, from three to six in number. In the _Simiidæ_ alone is there a broad sternum, or one consisting of a manubrium, followed by a single bone only, as in _Hylobates_. The Orang presents a peculiarity, in that the sternum long remains made up of ossifications arranged in pairs, side by side, successively. The true ribs are seven in number on each side in the highest forms, but in _Hylobates_ there are sometimes eight. In _Ateles_ there are sometimes nine pairs. In _Hapale_ the number varies from six to eight, and it is seven or eight in the other genera. The angles of the ribs are never so marked as in Man; although most marked in _Hylobates_. _Pithecia_ is distinguished by the greater relative breadth of the ribs. In no Ape is the thorax half as broad again as it is deep from back to breast; but in the _Simiidæ_ its transverse diameter exceeds its depth by from about one-fourth to a little under one-third of the latter. In _Ateles_, and sometimes in _Mycetes_, the thorax is wider than deep, but in all the rest it is deeper than wide.

In regard to the appendicular skeleton it may be observed that the Gorilla and Orang make the nearest approach to Man in the form of the scapula; and that the supraspinous fossa of this bone is largest in _Gorilla_ and _Mycetes_, being remarkably small in _Simia_. The _Cebidæ_ have a distinct suprascapular notch which is often converted by a bar of bone into a foramen; this bar in _Mycetes_ giving rise to a peculiar flat process. The acromion and coracoid processes are most developed in the _Simiidæ_ and _Ateles_.

The relative length of the fore and hind limbs has been already briefly touched upon. The humerus closely resembles that of Man throughout the suborder; the nearest approximation occurring in the _Simiidæ_. As in the Lemuroidea, this bone never has an entepicondylar foramen, but in many of the American forms it has a supracondylar perforation. The radius and ulna, like the tibia and fibula, are always perfectly distinct throughout their length; and the hand can be pronated and supinated upon the forearm. Man, the Gorilla, and the Chimpanzee differ from other forms in having no os centrale in the carpus.

The brain of Apes is always much smaller in absolute dimensions than in Man. Thus, according to Professor Mivart,[663] “the cranial capacity is never less than 55 cubic inches in any normal human subject, while in the Orang and Chimpanzee it is but 26 and 27½ cubic inches respectively. The relative size of the brain varies inversely with the size of the whole body, but this is the case in warm-blooded vertebrates generally. The extreme length of the cerebrum never exceeds, as it does in Man, two and a quarter times the length of the basicranial axis. The proportion borne by the brain to its nerves is less in the Apes than in Man, as also is that borne by the cerebrum to the cerebellum. In general structure and form the brain of Apes greatly resembles that of Man. Each half of the cerebrum contains a triradiate lateral ventricle, and though in some _Cercopithecidæ_ the posterior cornu is relatively shorter than in man, it again becomes elongated in the _Cebidæ_, and in many of the latter it is actually longer relatively than it is in man. The posterior lobes of the cerebrum are almost always so much developed as to cover over the cerebellum, the only exceptions being the strangely different forms _Mycetes_ and _Hylobates syndactylus_. In the latter the cerebellum is slightly uncovered, but it is so considerably in the former. In _Chrysothrix_ the posterior lobes are much more largely developed relatively than they are in man. The cerebrum has almost always a convoluted external surface. In this group, however, as in mammals generally, a much-convoluted cerebrum is correlated with a considerable absolute bulk of body. Thus in _Hapale_ (and there only) we find the cerebrum quite smooth, the only groove being that which represents the Sylvian fissure. In _Simia_ and _Gorilla_ and _Anthropopithecus_, on the contrary, it is very richly convoluted. A hippocampus minor is present in all Apes, and in some of the _Cebidæ_ it is much larger relatively than it is in Man, and is absolutely larger than the hippocampus major. Of all Apes, the Orang has a brain which is most like that of Man; indeed, it may be said to be like Man’s in all respects, save that it is much inferior in size and weight, and that the cerebrum is more symmetrically convoluted and less complicated with secondary and tertiary convolutions. If the brain of _Simia_ be compared with that of _Gorilla_ and _Anthropopithecus_, we find the height of the cerebrum in front greater in proportion in the former than in the latter; also the bridging convolutions, though small, are still distinguishable, while they are absent in the Chimpanzee. Nevertheless this character cannot be of much importance, since it reappears in _Ateles_, while two kinds of the genus _Cebus_ (so closely allied as to have been sometimes treated as one species) differ strangely from each other in this respect. The corpus callosum, in Apes generally, does not extend so far back as in Man, and it is very short in _Pithecia_. In the Orang and Chimpanzee there are, as in Man, two corpora albicantia, while in the lower Monkeys there is but one. The vermis of the cerebellum is larger in the _Cebidæ_ than in the _Simiidæ_ and _Cercopithecidæ_. In all Apes below the _Simiidæ_ each lateral lobe of the cerebellum gives off a small lobule, which is received into a special fossa of the petrous bone. Certain prominences of the medulla oblongata, termed corpora trapezoidea, which are found in lower mammals, begin to make their appearance in the _Cebidæ_.”

The organs connected with the functions of alimentation, circulation, and excretion, as well as the muscles, conform generally to the type obtaining in Man, of which full description will be found in works on human anatomy. The tongue is longer in Apes than in Man; and a uvula is generally present, although rudimentary in the _Cebidæ_. The peculiar sacculation of the stomach in the subfamily _Semnopithecinæ_ has been already mentioned; this sacculation is most developed at the cardiac extremity, where it somewhat resembles a colon spirally coiled. In _Hylobates_ the stomach is very like that of Man, differing only in the more elongated and distinct pylorus. _Pithecia_ has a more globular stomach, while in _Hapale_ the cardiac and pyloric apertures are approximated. The intestine of Apes is devoid of valvulæ conniventes, and it is only in Man and the _Simiidæ_ that the colon is furnished with a vermiform appendage. The colon varies from a fully sacculated form in _Hylobates_ to a smooth one in _Cebus_.

The liver of Apes is subject to a considerable amount of variation. In the _Simiidæ_ it comes more or less close to the human type; that of the Orangs being usually divided only into two principal lobes by the umbilical vein, and showing no trace of lateral fissures. In the Gorilla these fissures are present, so as to produce right and left lateral and central lobes. _Hylobates_ has a liver (Fig. 352) which perhaps is nearer to the human than that of any of the other _Simiidæ_. In the _Cercopithecidæ_ the liver differs from that of the _Simiidæ_ by the deeply cleft lateral fissures, and has a comparatively small and pointed caudate lobe. The enormous size of the stomach in _Colobus_ causes the liver to be very narrow, and pushed to the left side. The liver of the _Cebidæ_ (Fig. 336) and _Hapalidæ_, in addition to the deeply cleft lateral fissures, is characterised by the great size and quadrangular form of the caudate lobe (_c_), which attains its maximum development in _Ateles_. The gall-bladder is always present.

The larynx is in many Apes furnished with sac-like appendages, which are variable in different species as regards number, size, and situation. They may be dilatations of the laryngeal ventricle, as in _Simia_, _Gorilla_, and _Anthropopithecus_, or they may open above the false vocal chords so as to be extensions of the thyro-hyoid membrane, as in _Hylobates_. There may be but a single median opening in the front part of that membrane at the base of the epiglottis, as in the _Cercopithecidæ_. There may be a single median opening at the back of the trachea, just below the cricoid cartage, as in _Ateles_; there may be but a single sac, or there may be five, as sometimes in _Mycetes_. These may be enormous, meeting in the middle line in front and extending down to the axillæ, as in the Gorilla and Orang. A sac may occupy the cavity of the expanded body of the hyoid, as in _Mycetes_.

The hyoid has its basilar part generally somewhat more convex and enlarged than in Man; but in _Mycetes_ it becomes greatly enlarged and deeply excavated, so as to form a great bony bladder-like structure. The posterior cornua of the hyoid (thyrohyals) are never entirely absent, but the anterior or lesser cornua may be so, as in _Mycetes_. The anterior cornua never exceed the posterior cornua in length; but they may be (_e.g._ in _Cercopithecus_) more largely developed relatively than in Man, and may even be jointed, as in _Lagothrix_.

The lungs have generally the form of those of man; but the right lung may have four lobes, as in _Hylobates_. The great arterial trunks in _Simia_, _Gorilla_, and _Anthropopithecus_ are arranged as in Man. In _Hylobates_ and the lower Apes, however, the left carotid artery may take its origin from the innominate artery.

In regard to their distribution in time the earliest record that we as yet have of the occurrence of Apes is in the Middle Miocene of Europe, where forms are met with apparently so closely allied to some of the higher existing types that it is evident we must look much farther back before we can get any clue to the origin of the suborder. Since all the known fossil Old World Apes are referable to the _Simiidæ_ or _Cercopithecidæ_, and no representatives of these families have been obtained from the Tertiaries of America, it would appear that the distinction of the Apes of the Old World from those of the New is of very old standing.

At the present day Apes are mainly confined to tropical and subtropical regions. In the Old World _Macacus inuus_ is found as far north as Gibraltar, _M. tibetanus_ and _Semnopithecus roxellanæ_ inhabit western Tibet, while in Japan we have _M. speciosus_. In the New World one species of _Ateles_ is known to occur as far north as latitude 19° in Southern Mexico, and may range a few degrees higher. To the southward species are found near the Cape, in Timor, and the Malay Archipelago; while in America they range in Brazil and Paraguay to about latitude 30°. The Tibetan species are found at a very high elevation; and in the outer Himalaya the Langurs (_Semnopithecus_) may be seen in winter and spring leaping from bough to bough of snow-covered pines.

Apes are very abundant in the Ethiopian and Oriental regions, as well as in that part of America which extends from Panama to Southern Brazil. Ceylon, Borneo, Sumatra, and Java may be mentioned as islands where Ape-life attains great development; but they are unknown in Madagascar and the West Indian Islands, and of course in the Australasian region.

We have already alluded to the circumstance that while the _Simiidæ_ and _Cercopithecidæ_ are exclusively confined to the Old World, the _Cebidæ_ and _Hapalidæ_ are equally restricted to the New, and we may accordingly proceed to notice a few points in relation to generic distribution. Of the larger _Simiidæ_ the Gorilla and Chimpanzee are confined to Equatorial Africa, and the Orang to Malayana; but there is evidence of the former existence of a species of Chimpanzee (_Anthropopithecus_) and not improbably of an Orang (_Simia_) in Northern India. The Gibbons (_Hylobates_) are now exclusively Oriental. Europe has only _Macacus inuus_ of Gibraltar, also found in Africa north of the Sahara, and therefore strictly Palæarctic in distribution. The Ethiopian region includes in the _Cercopithecidæ_ the genus _Colobus_ (the African analogue of _Semnopithecus_), _Cercopithecus_, and the Baboons (_Cynocephalus_, etc.) The Baboons range, however, into Arabia and Syria, and also existed during the Pliocene epoch in Northern India. _Semnopithecus_ and _Macacus_ are very characteristic of the Oriental region; but, as already mentioned, outlying species extend into various parts of the Palæarctic region. _Macacus_ has indeed a very wide distribution, extending from Gibraltar and North Africa to Japan. The allied _Cynopithecus_, represented only by _C. niger_ of Celebes, approximates to the Baboons; while the one species of _Nasalis_ is peculiar to Borneo. Remains of _Semnopithecus_ and _Macacus_ occur in the Tertiaries of India and Europe, which also yield allied extinct types noticed in the sequel.

In America, north of Panama, the genera known to be represented are _Chrysothrix_, _Nyctipithecus_, _Cebus_, _Ateles_, _Mycetes_ and _Hapale_ in Veragua; _Nyctipithecus_, _Cebus_, _Ateles_, and _Mycetes_ in Costa Rica and Nicaragua; _Ateles_ and _Mycetes_ in Guatemala; and _Ateles_ in Southern Mexico. Brazil is the headquarters of the American Apes; but different portions of that vast region have a somewhat distinct Ape fauna. Thus the genus _Eriodes_ appears in South-Eastern Brazil to represent the species of _Ateles_ inhabiting the more northern and western parts of the empire. Southwards, the genera _Cebus_, _Mycetes_, _Chrysothrix_, and _Callithrix_ extend farthest; but they do not probably all extend to the farthest limit yet known, namely 30° S. The species found farthest south are _Mycetes caraya_, _Cebus fatuellus_, and _Callithrix personatus_.

_Family_ HAPALIDÆ.

Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₂; total 32. No bony external auditory meatus, a broad internarial septum, and no cheek-pouches. Tail non-prehensile; no ischiatic callosities. Pollex not opposable; a long, curved, and pointed claw to all the digits except the hallux.

This family, which includes the smallest representatives of the suborder, commonly known as Marmosets, is confined to the New World. In addition to the diagnostic characters given above, it may be mentioned that the pollex is elongated and the hallux very small, while the pectoral limbs are not longer than the pelvic pair; and the tail is long and more or less thickly covered with elongated hairs.

The dentition of the Marmosets sufficiently distinguishes them from all other members of the suborder, although they are evidently nearly allied to the _Cebidæ_. The small size of the hallux, and the total incapacity of the pollex to oppose itself in the least degree to the other digits, as well as the presence of claws on all the digits of the manus, are, however, equally characteristic features. These animals (Fig. 337) are not larger than Squirrels, and are of active arboreal habits, living in small companies, and adding insects to the ordinary fruit diet. Frequently, as in the figured species, the head is furnished on either side with a long tuft of hair projecting outwards and backwards. They give birth to as many as three young ones at a time, and thereby differ from all other members of the suborder, in which one is the normal number. They are divided into two genera, according to the proportionate size of the lower canine to the incisors; but some species present an intermediate condition, so as to render this distinction of somewhat doubtful value.

_Hapale._[664]—Lower canine not longer than the incisors. A number of species have been described, among which may be mentioned _H. jacchus_, _H. albicollis_, _H. aurita_, and _H. humeralifer_. Remains of species of this genus have been found in the cavern-deposits of Brazil.

_Midas._[665]—Lower canine considerably longer than the incisors. No less than twenty-four species of this genus have been named, among which the Silky Marmoset (_M. rosalia_) of Columbia, the Pinche Monkey (_M. œdipus_) of South-Eastern Brazil, and the Golden Marmoset (_M. chrysoleucas_, Fig. 337) are well-known types.

_Family_ CEBIDÆ.

Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 36. Tail frequently prehensile; digits with nails; other characters as in the _Hapalidæ_.

The members of this American family are at once distinguished by the dental formula, which is numerically higher than in any other Apes. The various species range over the whole of tropical America, but are most abundant in the dense forest regions of Brazil, where they live a completely arboreal life, to which the prehensile tails of many of them are so specially adapted. They are in most respects closely allied to the _Hapalidæ_, but the pollex diverges somewhat from the plane of the other digits; while the retention of the third molar is a very distinctive feature. None of the species attain the dimensions of the larger _Cercopithecidæ_ of the Old World. The genera are usually arranged in five subfamilies.

Subfamily =Mycetinæ=.—Lower incisors vertical; hyoid bones enormously inflated; tail long and prehensile, naked beneath at the end; pollex well developed.

_Mycetes._[666]—The sole representatives of this subfamily are the well-known Howling Monkeys, all of which are included in the genus _Mycetes_. They are of more bulky build, and have more produced muzzles than the other members of the family. The truncated occipital region, and the extraordinary development of the rami of the mandible, especially of their angular and ascending portions, are the chief peculiarities by which the skulls (Fig. 338) of the members of this genus are characterised. The last named character, which is more marked in the male than in the female sex, is related to the enormous size of the vocal organs, which the rami of the mandible enclose and protect. The inflated hyoid bone, which forms a deep cup, is shown in the figure. The Howlers are subject to great individual and sexual variation of colours, so that the discrimination of species from local races is difficult. In one species the male is black and the female straw-coloured; and several of the species have bright red or golden hair on the flanks. In disposition these creatures are sluggish and stupid, but their chief characteristic is their prodigious power of voice. Mr. Bates, in his _Naturalist on the Amazons_, observes that “when Howlers are seen in the forest there are generally three or four of them mounted on the topmost branches of a tree. It does not appear that their harrowing roar is emitted from sudden alarm; at least it was not so in captive individuals. It is probable, however, that the noise serves to intimidate their enemies.”

Several species have been described, the Red Howler (_M. seniculus_) and the Ursine Howler (_M. ursinus_) being well-known forms. Remains of this genus probably referable to existing types are found fossilised in the cavern-deposits of Brazil. An allied fossil form from the South American Pleistocene has been described as _Protopithecus_.

Subfamily =Pitheciinæ=.—Lower incisors inclined forward at their summits; hyoid bone normal; tail long or short, non-prehensile; pollex well developed. Two genera are included in this subfamily, readily distinguished by the length of the tail.

_Pithecia._[667]—The Sakis, as the representatives of this genus are commonly termed, are readily characterised by the length of the tail; the angle of the mandible is expanded, although less so than in _Mycetes_. A number of species have been described, the Black Saki (_P. satanas_) of the Lower Amazons, being one of the best known. While some species, like _P. hirsuta_, have long hair covering the whole of the head, body, and tail, in others only the head, or the cheeks and chin, are so clothed.

_Uacaria._[668]—The Uakari Monkeys differ from all the other _Cebidæ_ by their short Baboon-like tail. The Bald Uakari (_U. calva_) of the Rio Negro, and the closely allied _U. rubicunda_ of the Upper Amazons, are remarkable for their scarlet face, which forms a striking contrast to the long, silky, whitish hair covering the body. According to Mr. Bates, the Uakaris live in forests which are inundated during a great part of the year, and never descend to the ground; they appear to be rare and of local distribution. The third species, _U. melanocephala_, differs considerably from both the others. The cæcum of _U. calva_, according to Mr. F. E. Beddard, measures upwards of “10 inches along the greater curvature; it is separated from the colon by a very marked constriction; it is not sacculated, and when fully distended with air is curved on itself into a little less than a circle; it is furnished with a well-developed median frenum carrying blood-vessels.” A similar type of cæcum is also found in _Callithrix_ and _Pithecia_.

Subfamily =Nyctipithecinæ=.—Lower incisors vertical; hyoid normal; tail long, non-prehensile; pollex well developed.

Three genera are included in this subfamily, the species being partly insectivorous.

_Callithrix._[669]—Head small, depressed, and not elongated; nares widely separated; canines small; angle of mandible expanded as in _Pithecia_; tail with long hair.

This genus comprises several small species, mostly from Brazil and the Amazons, and commonly known as Teetees, one of the best-known species (_C. moloch_, Fig. 339) being represented in the accompanying woodcut. The smaller eyes and the more widely separated nostrils distinguish them from _Nyctipithecus_; while the small canines and the bushy tail readily mark their distinction from _Chrysothrix_. Remains of _Callithrix_ have been found in the Brazilian caves.

_Chrysothrix._[670]—Head greatly elongated; orbits large and closely approximated; canines well developed; tail with comparatively short hair.

The small Squirrel Monkeys, of which four species have been described, are characterised by the great backward projection of the occipital region of the skull, and by orbits approximating in size to those of the next genus.

_Nyctipithecus._[671]—Head rounded; orbits very large, separated by a narrow septum; nares somewhat approximated.

The Douroucoulis (Fig. 340), as the members of this genus are called, are of nocturnal habits, in association with which the eyes are of enormous dimensions, as in the Lemuroid genus _Loris_. The following account, of two species of this genus is taken from Mr. Bates’s _Naturalist on the Amazons_: “They sleep all day long in hollow trees, and come forth to prey on insects and eat fruit only in the night. They are of small size, the body being about a foot long, and the tail 14 inches, and are thickly clothed with soft gray and brown fur, similar in substance to that of the Rabbit. Their physiognomy reminds one of the Owl or Tiger-Cat; the face is rounded and encircled by a ruff of whitish fur; the muzzle is not at all prominent; the mouth and chin are small; the ears are very short, scarcely appearing above the hair of the head; and the eyes are large and yellowish in colour, imparting the staring expression of nocturnal birds of prey. The forehead is whitish, and decorated with black stripes, which in one of the species (_N. trivirgatus_) continue to the crown, and in the other (_N. felinus_) meet on the top of the forehead. _N. trivirgatus_ was first described by Humboldt, who discovered it on the banks of the Cassiquiare, near the headquarters of the Rio Negro.”

Subfamily =Cebinæ=.—Lower incisors vertical; hyoid bone normal; tail long and prehensile; pollex present or absent.

This subfamily includes the typical members of the family, which are arranged in four genera.

_Ateles._[672]—Form slender; limbs very long; fur not woolly; pollex absent; tail naked beneath distally; nails not much laterally compressed and pointed.

This genus includes the well-known Spider Monkeys (Fig. 341), which by their long limbs and tail are admirably adapted to a purely arboreal life, although they lack the active and agile habits of the Old World Gibbons. The tail with the under surface of its extremity naked affords the most completely prehensile type of this organ, and can sustain the weight of the whole body. Objects are not unfrequently grasped by it and brought within reach of the hand or mouth. Owing to the absence of the pollex the power of grasping is very imperfect in the hand. At least fourteen species of this genus have been described, among the best-known being _A. melanochir_ (Fig. 341), _A. paniscus_ of Guiana, _A. geoffroyi_ of Central America, _A. ater_ of Eastern Peru, and _A. hybridus_ of Colombia.

_Eriodes._[673]—Form slender; limbs very long; fur woolly; internasal septum narrower than usual in the family; pollex rudimentary; tail naked beneath distally; nails exceedingly compressed laterally, and pointed.

This genus is represented by three species from South-East Brazil, which, while closely allied to the true Spider Monkeys, differ by their woolly hair, the narrow internasal septum, the presence of a rudimentary pollex, and the great compression of the nails. The species are _E. arachnoides_, _E. hemidactylus_, and _E. hypoxanthus_.

_Lagothrix._[674]—Form rather robust; limbs moderate; fur woolly; pollex well developed; tail distally naked beneath.

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.