Ape

APEAPE (flap, Dutch; Affe, German; Affo, Old German; apa, Swedish and Irish; epa, Welsh), a word of uncertain, and not improbably African origin, and by some supposed to have originated in an imitation of the animal’s “chatter.”

The zoological group denoted by the term “ape,” when used in its widest sense, includes animals known by the familiar terms of “monkeys” and “baboons,” as well as others bearing the less known names of “sapajous,” “sakis,” and “marmosets.” In a more restricted sense the term “ape” is sometimes emphatically applied to those of the whole group which are most man-like in structure, namely, to the orang, the chimpanzee, the gorilla, and the gibbons.

Certain other animals, of very different structure, are generally associated in the same ordinal group with the apes. These other animals are the lemurs, or lemuroids; called also “half-apes,” after their German designation of Halbaffen.

By Linnaeus these creatures, together with bats and man, were placed in his highest and first order, to which he gave the name “Primates,” dividing its contents into the four genera, Homo, Simia, Lemur, and Vespertilio. The bats are now by universal consent removed from the order; and some eminent naturalists, notably Professor Alphonse Milne-Edwards, are disposed to remove from it the lemurs also; but in every case there can be no question but that the latter animals must at least rank as a sub-order, for which the term “Lemuroidea” has been proposed.

The question whether man should or should not be placed in the same zoological order with the apes, must be decided according to the principles of classification adopted. If that classification be purely morphological, i.e., be determined by form and structure only, he cannot well be separated from them, at least by any naturalist who would also include the lemurs in such order. The Linnean name “Primates ” has been retained for the ape order, not only by naturalists who (like Professor Huxley) retain man within its limits; but also by others (e.g., the Professors Isidore Geoffroy St Hilaire and Gervais), who consider that he should be excluded from it. Cuvier, on the other hand, proposed for the ordinal group of apes and lemurs only the term Quadrumanes (or four-handed), giving to that order, within which he placed man alone, the antithetical term Bimanes. In this he has been followed by very many naturalists, and in England, amongst others, by Professor Owen; and, perhaps, the majority of writers since Cuvier have bestowed on two distinct orders the names Quadrumana and Bimana respectively.

Priority of use determines our preference for the Linnean naxas“ Primates,” but this preference is reinforced by considerations derived from anatomy and physiology.

The whole of the apes, as indeed the whole of the halfapes also, differ from man in having the great toe, or (as it is called in anatomy) the hallux, so constructed as to be able to oppose the other toes (much as our thumb can oppose the fingers), instead of being parallel with the other toes, and exclusively adapted for supporting the body on the ground. The prehensile character of the hallux is fully maintained even in those forms which, like the baboons, are terrestrial rather than arboreal in their habits, and are quite quadrupedal in their mode of progression. It was this circumstance that led Cuvier to bestow the name Quadrumanes upon the apes and lemurs. Now, if we accept, with Professor Owen, as the definition of the word “foot,” “an extremity in which the hallux forms the fulcrum in standing or walking,” then man alone has a pair of feet. But, anatomically, the foot of apes (as well as that of half-apes) agrees far more with the foot of man than with his hand, and similarly the ape’s hand resembles man’s hand and differs from his foot. Even estimated physiologically, or according to use and employment, the hand throughout the whole order remains the special prehensile organ; while the predominant function of the foot, however prehensile it be, is constantly locomotive. Therefore the term Quadrumana is apt to be misleading, since, anatomically as well as physiologically, both apes and men have two hands and a pair of feet.

Apart then from man, the apes constitute the first sub-order of that which is the most man-like order of the class Mammalia (beasts), and which bears the name “Primates.” Such being the position of apes as a whole, they are zootomically divisible into a number of more and more subordinate groups, termed respectively families, subfamilies, and genera.

The following table exhibits what is believed to be, on the whole, the most natural and convenient arrangement of these groups of apes :— [table]

The limits of the present article exclude altogether from consideration the half-apes or Lemurs.

The whole of the apes may be characterised by the following zoological definition, the meaning of the terms of which will be explained later :—

Unguiculate, claviculate mammals, with a deciduate, dis-coidalplacenta and small allantois; with orbits encircled by and separated off from the temporal fossae by plates of bone; lachrymal foramen not opening on the cheek; posterior cornua of os hyoides longer than the anterior cornua; dental formula as in man, save that a true molar may be wanting, or that there may be a premolar in excess, or both; brain with zv ell-developed posterior cornua and with the cerebellum quite covered by the cerebrum, or only very slightly uncovered; hallux opposable, with a flat nail or none; a well-developed caecum; penis pendulous; testes scrotal; only two mammae, which two are pectoral; uterus not two homed; thumb sometimes rudimentary or absent.

The great group of apes thus characterised is divisible, as the foregoing table indicates, into two great families, which are sharply distinguished by geographical distribution as well as by structural differences. The first of these families, Simiadae, is strictly confined to the warmer latitudes of the Old World. The second family, Cebidae, is as strictly confined to those of the New World.

Of the three sub-families into which the Simiadae are divided, the first, Simiinae, contains only the orang, the chimpanzee, the gorilla, and the gibbons. These are the creatures which, anatomically, are the most like man of all the apes, on which account they are often called the t, ' anthropoid” apes. They are also termed, on account of the relative breadth of their breast-bone or sternum, the “latisternal” or “broad breast-boned” apes.

The orang (N. satyrus) constitutes the genus Simia, which gives its name to the whole family (Simiadae), as well as to the sub-family (Simiinae) to which it belongs. Of this genus there is but one certain species, which is, however, subject to considerable variation. The orang is exclusively confined to the islands of Borneo and Sumatra, where it frequents the swampy forests near the coast. It attains a height of about 4 feet 4 inches; but its bulk is considerable, its legs, however, being exceedingly short. Its arms, on the contrary, are exceedingly long, reaching down to the ankle when the animal is placed in an erect posture. In harmony with this structure the animal rarely assumes, naturally, a truly erect posture, but walks resting on the knuckles of its hands and the outer sides of its feet, the soles of the latter being turned mainly inwards. Its motions are ordinarily very slow and deliberate, and its demeanour in captivity is languid and melancholy. It is, in a "wild state, exclusively a vegetable feeder, and arboreal in its habits, forming in the trees a sort of nest or shelter of interwoven branches. The animal is covered with long, reddish-brown hair, and there are no naked spaces on the hinder part of the trunk. The forehead is rounded and rather high. Adult males are furnished with a longish beard on the chin, and they may also develop a large warty prominence, consisting of fibro-cellular tissue, on each side of the face. There is no vestige of a tail. The hands are very long; but the thumb is short, not reaching to the end of the metacarpal bone of the adjacent (index) digit. The feet have exceedingly long toes, except the great toe (hallux), which only reaches to the middle of the proximal phalanx of the index digit of the foot. The hallux is often destitute not only of a nail, but of the second or distal phalanx also; it· nevertheless possesses an opponens muscle. The orang has twelve pairs of ribs, and has, compared with man, an extra wrist bone, or an os intermedium in its carpus. The brain of the orang has the cerebrum greatly convoluted, and is altogether more like the brain of man than is that of any other ape. A prolongation is developed from each ventricle of the larynx, and these processes in the adult become enormous, uniting together in front over the windpipe, and forming one great sac which extends down between the muscles to the axilla. There are, however, no cheek pouches. The canine teeth, especially of the adult males, are very large.

The chimpanzee and gorilla together form the genus Troglodytes. Both of these species agree with the orang in being destitute of any rudiment of a tail, in having no cheek pouches, and no naked spaces at the hinder part of the trunk, as also in possessing tusk-like canines, and in the habit of resting on the knuckles of the hand in walking on the ground and of mainly dwelling in trees. The chimpanzee (T. niger) is found in Western Africa, from the Gambia to the Benguela, and extending inland to 2⅛ 4 E.

long. It is the most man-like of the latistcrnal apes in the proportions of its arms, as these only reach a little below the knees when the body is placed upright. It is of moderate stature, never appearing to exceed 5 feet in height In disposition it is lively and intelligent, and its playfulness in captivity contrasts greatly with the lethargy of the orang. The forehead is not rounded, but a bony, supra-orbital ridge extends transversely above the eyes. Its ears are very large, and it has distinct eyebrows, eyelashes, and whiskers. The pollex reaches nearly or quite to the base of the first phalanx of the index of the hand, and the hallux to the proximal end of the second phalanx of the index of the foot. There is no os intermedium, in the carpus. The laryngeal sacculus may, as in the orang, extend downwards to the axilla. There are thirteen pairs of ribs.

The gorilla (7 ’. gorilla) is also West African, but has a less extended range than the chimpanzee, namely, between the Cameroon and Congo rivers only. It is the largest ape known, attaining a bulk of body considerably exceeding that of man, though, on account of the shortness of its legs, it never seems to exceed the height of 5 feet 6 inches. It was first made known to modems by Dr Thomas Savage, but it appears to have been seen by Hanno of Carthage, in his voyage south of the pillars of Hercules. The gorilla has not such dark hair as has the chimpanzee, being blackish-dun in colour, and becoming grey when old. Its skin, however, is black. Its arms are longer than those of its congener, reaching half-way down the shin. Its pollex reaches but very little beyond the proximal end of the first phalanx of the index of the hand (slightly further than in the chimpanzee), and its hallux to about the distal end of the proximal phalanx of the index of its foot. The fingers and toes, however, are curiously syndactyle, being bound together by the integument to the ends of the proximal phalanges. The forehead is not rounded, the supra-orbital crest beinsj more prominent than even in the chimpanzee; the ears too are smaller relatively. The larynx is provided with enormous air-sacs, communicating with the ventricles and meeting over the trachea, and extending to the axilla with age. There is no os intermedium in the carpus, and there are thirteen pairs of ribs.

The gibbons, or long-armed apes, form the genus Hylo-bates, confined in the present day to the south-eastern continent of Asia and the Indian Archipelago. There are several species, but individual variation and sexual difference in colour are so great that their limits are not yet well defined. One well-marked species, the largest of the genus, is the siamang (77. syndactylus) of Sumatra, which is remarkable as being the ape with the best developed chin and widest breast-bone. It has also the second and third toes united by skin down to the last joint of each. Another well-marked form is the hoolock of Assam (77. hoolock). In the gibbons we first find that part upon which the body rests in sitting provided with naked callous spaces, termed (from that part of the haunch bone to which they are applied, the ischium) “ischial callosities; υ they are, however, still small. Though vegetable feeders, the gibbons are probably less exclusively so than are the yet higher apes before noticed. In captivity their manners are gentle, although their activity is surprising; especially remarkable are the enormous distances they can swing themselves by their long arms. In spite of this length of arm, which seems to render their bodily proportions so unlike those of man, the length of leg, when compared with the length of the trunk of the body, is more human than in either of the two preceding genera. Another point in which they approach nearest to man, is the quality of voice which at least some of the species (e.g. II. hoolock) possess.

None of the gibbons have any rudiment of a tail, and they have no cheek pouches, but the canines are elongated and tusk-like. When the body is erect, the arms are so long that they reach the ground. The hallux is well developed, reaching to the middle or end of the proximal phalanx of the index of the foot, while the pollex only attains to, or reaches a little beyond, the proximal end of the proximal phalanx of the index of the hand. There is an os intermedium in the carpus. The laryngeal sacs are no longer prolongations of the laryngeal ventricles, but open into the larynx above the false vocal chords. The number of species is, as has been said, doubtful, but the following kinds are often reckoned as distinct,— Syndactylus, Lar, Leuciscus, Agilis, Mulleri, Raffl,esii, Hoolock, Entelloides, Pileatus, and Funereus.

On leaving the gibbons, which close the series of Anthropoid apes, we come at once upon animals of very different aspect, and from creatures devoid of any vestige of a tail, we pass at once to monkeys, which have that organ at its maximum of development. These are the two genera Semnopithecus and Coldbus, which so closely resemble each other as to be hardly separable, but for their different geographical distributions. Together they form the subfamily Semnopilhecinoe, and agree in having, as well as the long tail, arms shorter than the legs, and a slender body. They have small ischiatic callosities, but no cheek pouches. Their nails are compressed and pointed. Their stomach is very elongated and exceedingly sacculated, and their hinder-most lower grinding tooth has five tubercles. The laryngeal sac opens medianly into the front of the larynx, and is an extension of the thyro-hyoid membrane. The thumb is small or absent.

The genus Semnopithecus, in which there is a small thumb, is confined to South-Eastern Asia from the Himalaya southwards, the Indian Archipelago being its headquarters. One species, Ä entellus (the hounaman), is an object of religious veneration to the Hindoos. Another very remarkable kind is found in Borneo. It is S. nasalis (the kahau, or proboscis monkey), and, as its name implies, it has an exceedingly long nose. In the young state, the nose is much smaller relatively, and is bent upwards. No similar structure was known to exist in any other ape whatever till quite recently. Now, however, the Rev. Father David (a Lazarist missionary, who has made many other important discoveries in zoology), has found high up in the cold forests at Moupin in Thibet, a large well-clothed species, with a small but distinct nose excessively turned up, on which account the name & roxellanoe has been bestowed upon it. It is remarkable that a form, reminding us of the young condition of S. nasalis, should have been discovered in a region so remote from the island of Borneo as is Thibet. It is also very remarkable that a monkey of a genus the home of which is the warm Archipelago of India, should be found in forests where frost and snow last several months in the year, when their only food is tree buds, and tender shoots and twigs. The species of the genus to be mentioned, besides Entellus, Nasalis, and Roxellanoe, are,— Nemoeus, Leucoprymnus, Latibar-batus, Obscurus, Nestor, Cucullatus, Johnii, Priamus, Cristatus, Maurus, Femoralis, Auratus, Frontatus, Siamensis, Mitratus, Flavimanus, Rubicundus, Albipes, Nigripes, and Schistaceus.

The genus Colobus is exclusively African, but the species composing it only differ from the Semnopitheci, in that the thumb is generally absent or reduced to a small tubercle, which may or may not support a nail. The species are — Guereza, Verus, Temminckii, Vellerosus, Fuliginosus, Satanas, Angolensis, Ursinus, Ferrugineus, Kirkii, and Palliatus.

We now come to the concluding genera of the apes of the Old World, together forming the third sub-family Cyno- pithecinoe. This is a very natural group, but one exceedingly difficult to subdivide in a satisfactory manner, because the different characters gradually alter as we pass from round-headed, long-tailed, and comparatively slender monkeys to dog-faced, short-tailed, and massive baboons. All the Cynopitliecinoe agree in having pretty well-developed thumbs and a single stomach, as also in having the sides of the face distensible, serving as pockets wherein food may be temporarily stored, and technically called “cheek pouches.” The hair is often annulated. The ischiatic callosities are larger than in the forms hitherto noticed, and in some kinds these parts become greatly swollen at the period of sexual excitement, the enlargement extending sometimes (as in Macacus cyclopis) even to the tail. The male external generative organs tend to assume a bright and varied coloration, which is often accompanied with vivid hues on and about the face. By common consent, the Cynopithednoe are divided into at least three genera, and by some naturalists (e.g. Μ. Isidore Geoffroy St Hilaire) they have been divided into as many as seven.

The first genus, Cercopithecus, includes those species of the sub-family, which by their length of tail and comparative slenderness, most nearly approach the members of the preceding sub-family. Many of the species (e.g. the Diana and white-nosed monkeys) are very attractive animais. Commonly the Cercopitheci have four tubercles to the last lower molar. The talapoin monkey (C. talapoin) has been made the type of a separate genus (Miopithecus), because it has but three such tubercles, while the mangabeys and white-eyelid monkeys (C. oethiops, collaris, and /uliginosus) have been separated off into a genus Cercocebus, because in them the last lower molar has five tubercles. All the Cercopitheci (including Miopithecus and Cercocebus) are African forms. Besides those already mentioned, the following species have been described by authors :— Nictitans, Petaurista, Cephus, Mona, Monoides, Diana, Labiatus, Leucampyx, Pygerythrus, Lalandii, Sa- boeus, Cynosurus, Ruber, Pyrrhonotus, Callitrichus, Rufo-υiridis, Albig ena, Erythrogaster, Werne d, Melanogenys, Ludio, Er y thrar chus, Ochraceus, Flavidus, Lunulatus, and Erxlebenii.

The next genus, Macacus, is Asiatic, with the exception of the Barbary ape, or magot (Jf. imius), which is found in Northern Africa and on the Rock of Gibraltar. Already, in some of the Cercopitheci, notably in the mangabeys, the muzzle has acquired a greater prolongation. This becomes still more marked in the Macaci. It is this greater production of muzzle, the greater size in the ischiatic callosities, the frequent shortness of the tail, and the different geographical distribution, which can alone be given as differentiating these animals from the Cercopitheci. In some kinds the tail is long. Occasionally (as in the wanderoo, Jf. silenus) it is tufted at the end and short. Sometimes, as in Μ. nemestrinus, it is very short, and occasionally, as in Μ. inuus, it is absent. On account of this absence of tail, this species has sometimes been made the type of a distinct genus, Inuus.

Another species, Μ. niger (from Celebes and Batchian), has, on account of the much greater production of its muzzle, been made the type of another genus, termed Cynopithecus.

The Macaci present us with the most northern forms of apes, namely, that of Gibraltar, and Μ. speciosus of Japan. Father David has lately brought from Moupin, in Thibet, a new species (Jf. thibetanus') which inhabits snowy mountains, and is clothed suitably for such a habitat, in thick and dense fur. In addition to the Macaci already mentioned, we may name the species Sinicus, Pileatus, Aureus, Cynomolgus, Silenus, Rhesus, Nemestrinus, Thibetanus, Ochreatus, Palpebrosus, Brunneus, Rufescens, Rheso-similis, Erythraeus, Cristatus, Tcheliensis, Cyclopis, Inornatus, Sancti-johannis, Lasiotus, Assamensis, Maurus, Philippin-ensis, and Nigrescens.

The remaining apes of the Old World are the baboons, which are entirely confined to Africa, and to that part of Asia which is zoologically African, namely, Arabia. These animals, which constitute the genus Cynocephalus, have the characters of the Macaci still further developed in having still larger callosities, and a muzzle so extremely produced as to give the head the appearance of that of a dog, whence their generic name. The general form has also here become very massive, and the limbs being sub-equal in length, the appearance, like the locomotion, is quadrupedal. But the baboons have not only the muzzle so greatly produced, they have also the nostrils terminal in position like those of a hound and unlike what we have yet met with. The species C. gelada of Abyssinia and C. obscurus form exceptions to this condition, as they have the nostrils placed as in the Macaci, on which account they have been made the type of a distinct genus, Theropithecus.

In the other Cynocephali, the tail may be moderately long, as in C. hamadryads, or very short, as in the mandrill, C. mormon. In the last-named species we again meet with much bulk of body, as it exceeds the chimpanzee in this respect. It is also remarkable for its bright coloration, the cheeks being brilliant blue, the nose vermilion, and the beard golden-yellow. Other species described are Sphinx, Olivaceus, Babuin, Anubis, Obscurus, Doguera, Porcarius, and Leucophaeus.

The baboons are the least arboreal and the least frugivorous of the Old World apes, some species, e.g., the chacma of Southern Africa (C. porcarius'), living habitually amidst rocks, and feeding on eggs, large insects, and scorpions, as well as on vegetable food.

In the whole series of Old World apes we find the same number of different kinds of teeth as in man, the dental formula being—

τ «Z« 1-1 2 — 2 λ 3—3 = 16 ∣

1 ∙ 2—2 u 1-1 i, · 2-2 3-3 16’

or thirty-two teeth in all. Again, in the whole series the two nostrils are divided the one from the other by a narrow septum; and if the skull be examined, a long bony tube (the meatus auditorius externus) is seen to lead inwards on each side to the internal ear. Moreover, the thumbs, when present, are always more or less opposable to the other fingers.

In passing to the second family of apes—the Cebidae, or apes of the New World—we find them to form a very distinct and easily-defined group, and a little experience readily enables an observer to pronounce at a glance that a given ape belongs either to the Old or the New World, as the case may be.

The Cebidae are more thoroughly arboreal in their habits than are the Simiadoe. Ranging over tropical America, they have their headquarters in the forests of Brazil, a region where most animal forms put on a more decidedly arboreal character. Accordingly, it is amongst the Cebidae that we meet with, for the first time, a special arboreal organ—namely, a prehensile taiL Such a tail has its free end curled, and capable of grasping with greater or less tenacity the objects about which it coils. Again, in the Cebidae, the septum between the nostrils is broad, instead of narrow, imparting to the physiognomy a markedly different character. In passing to these American apes we entirely lose cheek pouches and ischial callosities; while the thumb, even where best developed, is capable of but a very partial opposition to the other fingers, bending almost in the same plane with the latter, so as to be more like a fifth finger than a thumb. We also constantly find an additional premolar tooth on each side of each jaw, and that bony tube, the meatus auditorius externus, is wanting.

None of the Cebidae attain the bulk of the larger baboons, nor have any such prominent muzzles as have the latter

The Cebidae are subdivisible into five sub-families :—1. Cebinae; 2. Mycetinoe; 3. Pitheciinoe; 4. Nyctipithecinae ; and, 5. Hapalinae.

The first sub-family consists of the four genera, Ateles, Enodes, Lagothrix, and Cebus.

The genus Ateles is composed of the spider monkeys, which, as their name implies, have long and slender limbs. They have also a very long tail, which is in the highest degree prehensile, being naked beneath towards the tip, for more secure prehension. So powerful is the grasp of this organ that the whole body can be sustained by it alone. It even serves as a fifth hand, as detached objects, otherwise out of reach, can be grasped by it, and brought towards the hand or mouth. Their prehension is in other respects exceptionally defective, as the spider monkeys alone amongst the Cebidae (like the Colobi amongst the Simiadoe) have the thumb reduced to a mere tubercle. Their laryngeal sac opens medianly, but from the back part of the trachea, just below the cricoid cartilage.

The spider monkeys are very gentle in disposition, and, by this and by their long limbs and special fitness for treelife, seem to represent in an analogous manner in the New World the gibbons of the Old. Nevertheless, in spite of their admirable adaptation for arboreal life, their comparatively slow progression offers a marked contrast to the vigorous agility of the gibbons. Their hair is long, but not woolly. Species described are— Ater, Pentadactylus, Paniscus, Marginatus, Belzebuth, Melanochir, Hybridus, Vellerosus, Albifrons, Rufiventris, Variegatus, Griescens, Cucullatus, and Fuscipes.

Three species of ape having much general resemblance to spider monkeys have been erected into the genus Eriodes (E. arachnoïdes, hemidactylus, and hypoxanthus'). These animals, which are from South-Eastern Brazil, have the fur woolly, the thumb more or less rudimentary, the nails very laterally compressed, and the nostrils more approximated than in the other Cebidae.

The woolly monkeys, Lagothrix, differ from the two preceding genera in having the thumbs well developed. Their nails are compressed laterally, as in Eriodes, but their nostrils are not approximated. As their name implies, their fur is woolly. Like Eriodes and Ateles, they have the tail strongly prehensile, and naked beneath towards the tip. The species which have been described as distinct are— Canus, Humboldtii, Castelnaui, Tschudi, and Geoffroyi.

The genus Cebus, the typical genus of American apes, is composed of the sapajous, so commonly seen in captivity, and so much used for the exhibition of tricks of various kinds. Smaller in size, they are more robust in form than are the spider monkeys. They have well-developed thumbs, and their tail is curled at the end, but, not being naked beneath, is less strongly prehensile than in the three preceding genera. The sapajous have a pleasing voice, a flute-like whistling tone. The different species are very ill-defined, the individual differences being so numerous and so considerable. The species described are the following :— Capucinus, Hypoleucus, Elegans, Robustum, Apella, Cirrifer, Flaυus, Castaneus, Barbatus, Frontatus, Chrysopus, Variegatus, Versicolor, Leucocephalus, Flavescens, An-nellatus, Subcristatus, Capillatus, Fatuellus, and Vellerosus.

The next sub-family of American apes is very distinct, consisting, as it does, of a single genus, Mycetes, composed of the howling monkeys. These creatures are the most bulky of the American apes, and are those the muzzles of which are the most projecting. If the spider monkeys may be considered the analogical representatives of the gibbons, the howlers may similarly be esteemed those of the baboons. They are sluggish, and apparently stupid animals, but have a wonderful power of voice, facilitated by an enormous distension of the body of the hyoid bone into a large, deep, bony cup, sheltered between the jaws, which are specially deep for that purpose. Into this cup is received one of the three or five sacs with which the larynx is provided. The thyroid cartilage is very large. The howlers have long, very prehensile tails, naked beneath towards the tips. Their thumbs are well developed. Some of the species show much brilliance of colour, with bright red or golden hair on the flanks. There is, however, so much individual variation, or so many local varieties, that the species are as yet very little determined. The sexual difference in colour is great in one species—the male being deep black, and the female pale straw colour. Amongst the species described may be named— Seniculus, Ursinus, Caraya, Rufimanus, Niger, Villosus, and Palliatus.

The third sub-family of American apes is composed of very peculiar forms, termed Sakis, which are subdivided into two genera, Pithecia and Brachyurus, according as the tail is long or short. They are together distinguished from all the Cebidae yet noticed, by not having the tail prehensile, even when long; also by having the lower incisor teeth inclined forwards, instead of standing up vertically. Great differences as to the hair exist in this group, some having long hair over the whole body, others on the head, and others on the chin and cheeks, while a species of Brachyurus (A. Caimis') has the head naturally bald. Of the genus Pithecia, the following species have been described :— Leucocephala, Rufiventer, Monachus, Satanas, Chiropotes, Albinasa, and Chrysocephala. Of Brachyurus, besides Caimis, only Rubicundus has as yet been described.

The Brachyuri are the only American apes with short tails, and they are the least arboreal, frequenting bushes rather than trees. They are very timid creatures, and gentle, and rather slow in their movements. It is but very rarely that any of the Pitheciinae have been brought to Europe alive.

The next sub-family, Nyctipithecinae, contains three genera, which have a long but not prehensile tail, fairly-developed thumbs, and vertical lower incisor teeth. These animals are, in part at least, insectivorous.

The typical genus, Nyctipithecus, contains only the night-apes, or douroucoulis (2V. felinus, leτnurinus, oseryi, rufipes, and Spixii), which have, in harmony with their noctural habits, enormous eyes. The orbits, though closely approximated, are nevertheless separated by a complete bony system. The head is rounded, but greatly drawn out posteriorly. The nostrils are rather approximated.

The beautiful little squirrel monkey, or Saimiri, and three allied species (Ch. ustus, entomophagus, and Oerstedii), form the genus Chrysothrix. They are distinguished from all other apes by the great backward prolongation of the bony cranium, the orbits of which, though smaller than those of Nyctipithecus, are, nevertheless, separated, but by an imperfect bony septum.

A few other kinds of American apes, together forming the genus Callithrix, somewhat resemble the night apes, but that the eyes are much smaller, and the nostrils wider apart. They differ from Chrysothrix in having small canine teeth, and the tail furnished with long hairs. The species of this genus are— Moloch, Personatus, Amictus, Gigo, Melanochir, Biscolor, Bonacophilus, Omatus, and Cαsiαnecwenim.

There remains now to notice but one more group of apes, those which have been classed as the last sub-family —the Hapalinoe, marmosets, or oustitis. These animals are so different from all that have gone before that there is probably almost as much to be said for ranking them as a family by themselves as for considering them, as is here done, but a sub-family. Much, however, as they differ from all the other apes, they manifest their affinity to the rest of the Cebidae by the absence of the meatus auditorius externus, and by the presence of the extra premolar tooth on each side of each jaw. They have, however, the same total number of teeth as have man and the Simiadae. This is occasioned by their not possessing any third true molar, either above or below; so that their dentition thus differs from that of the Old World apes in two points, instead of only one. In all the apes we have yet noticed, except the orang, the hallux is well developed, while in the marmosets it is exceedingly small. The hand, however, is yet more exceptional, as the thumb is not at all opposable, while, in common with all the other fingers, it is furnished with a long, curved, and pointed claw. The tail is not prehensile, but long, and furnished with more or less elongated hairs. In several, and especially the more commonly seen species, a tuft of long hairs projects outwards and backwards on each side of the head. These animals are very small, the largest being about the size of squirrels. They are, like squirrels, active in their motions, and arboreal in their habits, living in small troops, and eating insects as well as fruit. They are very difficult to keep in captivity in northern climates; but, nevertheless, they have occasionally bred in England, bringing forth as many as three at a birth, while all the other apes habitually bring forth but one. There arc many different species of marmosets, and they have been divided into two genera, according as tho lower canine (eye) teeth arc or are not decidedly larger than the incisors (cutting-teeth) between them; those kinds in which the inferiorand incisor canines are almost of equal length being retained in the genus ∏apale, while those in which the lower incisors are much shorter than the adjacent canines are taken to form the genus Midas. It seems doubtful, however, whether this generic distinction can ultimately be maintained, an intermediate condition existing in some forms. The species of the genus Hapale are— Jacchus, Albιcottιs, Aunta, riumera~ lifer, Penicillata, Leucocephala, Melanura, and Pygmoea.

The species of the genus Midas are— Rosalia, Ghryso-melas, Oedijnis, Geoffroyi, Bicolor, Ursul·us, Rufimanus, Labiatus, Mystax, Rufoniger, Devilli, Nigrτfrons, Flavi∙ frons, ∏ligeri, Weddellii, Leucogenys, Melanurus, Argentatus, Chrysoleucus, Lagonotus, Graellsi, Pileatus, Elegantulus, and Rufiventer.

The characters of the subdivisions of the ape group may be synoptically expressed as follows :—

Family I. Simiadae.

2 3

P.M. ∩ Μ. 5; a bony meatus auditorius externus; pollex oppos- 2 ο

able, if present; tail never prehensile; intemasal septum narrow; often cheek pouches; often callosities; pectoral limbs sometimes greatly exceeding the pelvic limbs in length; pelvic limbs never much longer than the pectoral limbs; Old World habitat.

Sub-Family I. Simiince.

Pectoral limbs much longer than pelvic limbs; no tail; no cheek pouches; caecum with a vermiform appendix; sternum broad; sometimes no os intermedium in tho carpus; stomach simple.

1. Simia. — Head vertically produced; arms reaching to ankle; ribs, twelve pairs; an os intermedium; hallux very small; no ischiatic callosities; hair red; habitat Asiatic.

2. Troglodytes.— Head not vertically produced; arms not reaching more than half down the shin; ribs, thirteen pairs; no os intermedium; hallux well developed; no ischiatic callosities; hair black, dun, or grey; habitat African.

3. Hylobates.— Head not vertically produced; arms reaching to the ground; an os intermedium; hallux well developed; small ischiatic callosities; habitat Asiatic.

Sub-Family II. Scmnopithcdnae.

Pelvic limbs longer than pectoral limbs; tail very long; no cheek pouches; no vermiform appendix; sternum narrow; an os intermedium; ischiatic callosities; stomach complicated by saccula-tions; third lower molar always with five tubercles.

4. Semnopithecus.— Thumb small; habitat Asiatic.

5. Colobzιs.— Thumb generally absent; habitat African.

Sub-Family III. Cynopithcdnoe.

Pelvic and pectoral limbs sub-equal in length; tail long, or short, or absent; cheek pouches; no vermiform appendix; sternum narrow; an os intermedium; ischiatic callosities present, often very large; stomach simple; third lower molar sometimes with four tubercles.

6. Ccrcopitheczιs.— Muzzle more or less short; callosities moderate; last lower molar generally with four tubercles; tail long; habitat African.

7. Macacus.— Muzzle more or less elongated; callosities rather large; last lower molar with five tubercles; tail long, short, or absent; nostrils not terminal; habitat Asiatic, North African, or European.

8. Cynocephalus. — Muzzle very long; callosities very large; last lower molar with five tubercles; tail more or less short; muzzle swollen by enlargement of maxillary bone; nostrils almost always terminal; habitat African.

Family II. Cebidae. g

P.M. θ; no bony meatzιs auditorizιs externus; pollex never o opposable; tail often prehensile; internasal septum broad; no cheek pouches; no ischiatic callosities; no vermiform appendix; always an os intermedium; pectoral limbs never more than slightly exceeding in length the pelvic limbs; pelvic limbs sometimes much longer than the pectoral limbs; New World habitat.

Sub-Family I. Cebince.

3

Μ. 5 ; incisors vertical; tail long and prehensile; hyoid bone o moderate; thumb present or absent.

9. Atelcs.— Form slender; limbs very long; fur not woolly; intemasal septum as broad as usual in Cebidae; thumb absent; tail distally naked beneath; nails not much laterally compressed and pointed.

10. Eriodes.- Form slender; limbs very long; fur woolly; internasal septum narrower than usual in Cebidae; thumb rudimentary; tail distally naked beneath; nails exceedingly compressed laterally, and pointed.

11. Lagothrix.— Form rather robust; limbs moderate; fur woolly; internasal septum as broad as usual; thumb well developed; tail distally naked beneath.

12. Cebus. — Form rather robust; limbs moderate; fur not woolly; internasal septum as broad as usual; thumb well developed; tail not naked beneath distally.

Sub-Family II. Mycetince. g

Μ. g; incisors vertical; tail long and prehensile, naked beneath distally; hyoid bone enormous; form of body massive; thumb well developed; internasal septum as broad as usual.

13. Mycetes.

Sub-Family III. Pithcciince. g

Μ. g; incisors inclined outwards distally; tail long or short, never prehensile; hyoid bone^ moderate; thumb well developed; intemasal septum as broad as usual.

14. Pithecia. — Tail long.

15. Brachyurus.— Tail short.

Sub-Family IV. Nyctipithecince. g

Μ. gj incisors vertical; tail long, not prehensile; hyoid bone moderate; thumb well developed.

16. Nyctipithecus.— Head rounded; eyes enormous; nostrils rather approximated.

17. Chrysothrix. — Head exceedingly elongated; eyes large, closely approximated; canines well developed; hair of tail rather short.

18. Callithrix. — Head small, depressed, and not elongated; nostrils widely separate; canines small; hair of tail elongated.

Sub-Family V. Hapalinoe.

2

Μ. -; incisors vertical; tail long, not prehensile; hyoid bone A moderate; thumb elongated, not at all opposable; hallux very small; a long curved and pointed claw to all the digits, except the hallux.

19. Hapale.— Lower incisors and canines of equal length.

20. Midas.— Lower canines much longer than the lower incisors.

THE ANATOMY OF APES.

To describe generally the anatomy of apes would be, in fact, to describe in an elementary manner the general anatomy of man. It is necessary, therefore, here to assume that the reader has already an elementary knowledge of human anatomy, and to refer such readers as have not such knowledge to the article Anatomy. The External Form and Clothing.

The difference in bulk between the different members of the group (e.g. Troglodytes and Hapale) is extreme, being greater than that between a man and a common squirrel.

The proportions of the body as regards the relative lengths of the two pairs of limbs one with the other, and both with that of the trunk, vary considerably. Both pairs may be much elongated, as in Ateles and Hylobaies, and either sub-equally, as in the first of these genera, or with the arms very greatly in excess, as in the second. The legs may be excessively short, and the arms, at the same time, excessively long, as in the orang. Both pairs may be short and sub-equal, as often in the Cynopithecinoe. Only in the Nyctipithecinoe and Hapxalinoe does the excess in length of the lower limbs over the upper exceed or equal that which is found in man. The length of the tail presents some noteworthy points. At its first appearance it is found at once at its greatest absolute length, and also greatly developed relatively, being about twice the length of the trunk. Its greatest relative length is, however, attained in Ateles, where it reaches three times the length of the trunk. The constancy of the degree of its development varies much in different groups. In the greater number of genera it is long in all the species, and in some (Simia, Troglodytes, and Hylobates) it is absent in alL In others it may be long or short, or completely absent, e.g., in Alacacus. The form of the head presents great differences—it may be rounded, as, e.g., in Ateles; produced vertically, as in Simia; drawn out posteriorly to an extreme degree, as in Chrysothrix; or anteriorly, as in Cynocephalus. A production of the muzzle, necessitated by the presence of large teeth, exists already in Troglodytes; but in the baboons, not only is this prolongation carried much further, but the terminal position of the nostrils gives an emphatically dog-like aspect to the face.

The eyes may be small compared with the size of the head, as in the baboons; they may, on the contrary, attain a relatively enormous size, as in Nyctipithecus. They are always forwardly directed, and never much more separated one from another than in man. They may, however, be much more closely approximated, as notably in Chrysothrix.

The external ears are always well developed, and have very generally their postero-superior angle pointed. They may be large and small in the same genus, as in Troglodytes. Only in the gorilla do we find present, even in a rudimentary condition, that soft depending portion of the human ear which is termed the “lobule.”

The nose has scarcely ever more than a very slight prominence, and yet an enormous development is to be met with in Semnopithecus nasalis ; while in & roxellanoe we find a sharply prominent, though smaller and extremely upturned, nose. The hoolock gibbon also possesses a prominent but slightly aquiline nose. The terminal position of the nostrils in Cynocephalus has been just mentioned. These apertures may be closely approximated, as in all the Simiadae, or they may be separated one from the other by a broad septum, as in the Cebidae, its breadth, however, varying somewhat in different genera, as, e.g., in Ateleβ and Eriodes, and in Callithrix and Nyctipithecus.

The lips are generally thin, but may be very extensive, as in Simia.

The hands are generally provided with thumbs, though these organs (as in Colobus and Ateles) may be represented only by small nailless tubercles. The thumb (pollex) is more human in its proportions in the chimpanzee than in any other of the highest apes. As compared with the length of the hand, it is most man-like in the lowest Cebidae, e.g., Chrysothrix and Hapale. In spite of greater relative length, however, it may but little merit the name of thumb, as it is but slightly opposable to the other digits in any of the Cebidae, and is not at all so in the Hapalinoe.

The hallux (great toe) is never rudimentary like the pollex. It is never, as it often is in man, the longest digit of the foot, but is constantly the shortest one. As compared with the entire length of the foot, it is most human in the chimpanzee and some gibbons, and smallest of all in the orang, and next smallest in Hapale. More detailed proportions will be more appropriately given in speaking of the skeleton.

Every digit is provided with a nail, except the hallux of the orang and those rudimentary tubercles already spoken of as representing thumbs in Ateles and Colobus. The nail of the hallux is flat in every species, but the other nails are never so flat as are the nails of man. The lateral compression of the nails becomes more strongly marked in some Cebidae, e.g., in Eriodes, but attains its extreme in the Hapalinoe, where every nail, except that of the hallux, assumes the form of a long, curved, and sharply-pointed claw.

All the apes, without exception, differ from man in having the body almost entirely clothed with copious hair, and especially in never having the back naked. In the gibbons, the Semnopithecinoe, and the Cynopithecinae, naked spaces (ischiatic callosities) are present on that part of the body which is the main support in the sitting posture. These naked spaces increase in size as we descend through the series of Cynopithecinae, and are subject to a tumefaction (sometimes excessive and extending to parts adjacent) at the season of sexual excitement. Such naked spaces are never found in any of the Cebidae. No ape has so exclusive and preponderating a development of hair on the head and face as exists in most men. As to the head, long hair is found thereon in Hapale oedipus and in some of the Semnopitheci, whilst certain of the Macaci (as, e.g., the Chinese bonnet monkey, Μ. sinicus) have the hair of the head long, and radiating in all directions from a central point on the sinciput. A beard is developed in the male orang, and Cercopithecos Diana has long hair on the cheeks and chin. The wanderoo (Macacus sιlenus) has the face encircled by a kind of mane of very long hairs, and many of the marmosets have a long tuft of hairs on each side of the head. The American apes exhibit some extremes respecting hair development. Thus in some of the howlers (as in some of the Colobi of the Old World) the hair of the flanks is greatly elongated. Some also have an elongated beard, but the latter structure attains its maximum of development in the couxio (Pithecia satanas). Some of Pitheciinae have the hair of the whole body and tail very long, others have the head of the female furnished with elongated hair, while another species (Brachyurus calvus) has the head bald. Long hair may be developed from the shoulders, as in Cynocephalus hamadryas and Hapale humeralifer; or may form a tuft at the end of the tail, as in Macacos silenus, Cynocephalus hamadryas, and Cynocephalus gelada.

The direction of the hair may sometimes vary in nearly allied forms. Thus the hairs on the arm and forearm respectively may be so directed that the apices converge towards the elbow. Such is the case in most of the lati-stemal apes, yet in Hylobates agilis all the hair of both these limb segments is directed towards the wrist.

The hair presents generally no remarkable character as to its structure. It may, however, assume a very silky nature, as in Hapale rosalia, or assume the character of wool, as in Eriodes, and as in that remarkable form recently discovered by Father David, Macacus thibetanus. The last named species inhabits the snowy ranges of the Thibet mountains, and is provided for this habitat by a modification in its hairy clothing similar to that which suited the extinct mammoth for the severity of its Siberian home. This fact as to Μ. thibetanus has an interesting bearing on fossil forms, which we shall have to consider later.

Great brilliance of colour is sometimes found in the naked parts of the body, particularly in the Simiadoe, and especially in the regions of the face and sexual organs. In some of Cercopitheci and Cynocephali, rose colour, turquoise blue, green, golden yellow, and vermilion appear, in various combinations, in one or other or both of these regions, and become especially brilliant at the epochs of sexual excitement.

The Skeleton.

The skeleton of apes generally, if we except the tail, consists of but few more bones than that of man. The proportions of its parts, except as regards the relative length of the limb bones, are also much as in man; nor are their shapes, except those of the jaws and haunch bones, greatly different. The same general resemblance may be predicated of their minute structure, though the osseous tissue is generally rather dense, and the medullary cavity in the long bones small The Axial Skeleton.—The Skull.

The axial skeleton consists of the skull and the vertebral column, and the general shape of its more anterior portion, the skull, has already been indicated when speaking of the head as part of the external form. It is scarcely ever so evenly balanced on the occipital condyles as in man.

The artificial division of the skull into a cranial and a facial portion may be here conveniently adopted from human anatomy. The proportion of the latter portion to the former varies greatly from age and sex, owing mainly to the differences produced through the development of large and powerful canine teeth in the adult males of most species. This proportion also varies in an irregular manner as we descend (through the series of apes) from those which are most like man. Thus the facial part is already very large in the orang and chimpanzee, much more so than in Scmnopithecus, where most of the ape cranial characters are moderately developed, or even than in many Cercopitheci; but it attains its maximum of relative size in the Cynocephali, above all in C. porcarius. In the Cebidae the facial part is relatively smaller than in the Simiadae, with the exception of Mycetes, while in Chrysothrix the facial portion of the skull is relatively smaller than even in man himseif. The relation of the face to the cranium (or brain case) is best shown by the craniofacial angle, which is estimated by means of two lines, one drawn parallel to the base of the skull (from the front margin of the occipital foramen to the anterior end of the cerebral surface of the presphenoid), the other drawn from the front end of that base to the middle of the lower margin of the upper jaw.

No ape, especially no ape of the Old World, presents so elevated and rounded a contour in the frontal region as does man. It is in American forms, especially in the genus Pithecia, that we find the greatest resemblance to man in this respect; but the skull is lofty in the orang.

The convexity of the occiput is well marked in Simia, Troglodytes niger, and Hylobates, while in the inferior Simiadae it is flat. Its maximum of production, however, is met with in the genus Chrysothrix.

Ridges for muscular attachment, or other bony prominences, more or less disguising the rotundity of the cranium, are very generally developed, except in the smallest species. Such ridges are met with at once at their very maximum of extent in Troglodytes gorilla. In that animal an enormous sagittal ridge traverses the middle of the sinciput antero-posteriorly, joining at its hinder end a prodigious lambdoidal crest for the insertion of the muscles of the neck. A very largely developed supra-orbital ridge runs transversely above the orbits, which it obliquely overhangs. The orang has no supra-orbital ridge, but in the other large Simiadoe all these ridges are more or less developed, and moderate sagittal and lambdoidal ridges are found in Mycetes, Cebus, Pithecia, and some other of the Cebidae.

The mastoid process never attains in apes the large relative size it has in man; but it is prominent in the baboons and larger Macaci, as well as in Troglodytes, its development bearing relation to the size and weight of the head. As the mastoid diminishes we find that the under surface of the petrous bone assumes a swollen or “bullate’’ condition.

The orbits are in T. gorilla much as in man, but in the orang they are more rounded. They become very large in Hylobates, but attain an enormous size in Nyctipithecus. The extent to which each orbit opens into the adjacent temporal fossa, i.e., the size and shape of the sphenomaxillary fissure, varies considerably. It is narrow and much elongated in the gorilla and in Cynocephalus ; it is short in the Semnopithecinoe and in Ateles, but opens widely so as to expose the vidian foramen. It is most completely closed of all in Mycetes, where it sometimes all but disappears entirely. The olfactory chamber is narrow and deep in the lower Simiadoe. The cribriform plate of the ethmoid is generally separated from the presphenoid by the junction of the orbital plates of the frontal. Such, however, is not the case in the orang and chimpanzee, though it is so in the gorilla and in Hylobates.

The plane of the foramen magnum, as compared with the basi-cranial axis, varies with the projection of the occiput. It generally forms a less open angle with that axis than in man, but in Chrysothrix the angle is yet more open than in the human skull.

The zygomata are arched both outwards and upwards in the gorilla and some baboons, but decrease in relative as well as absolute size in the smaller forms,—notably in Chrysothrix. No long slender styloid process is normally attached to the skull, though such may be the case in Cynocephalus. The vaginal process never attains the size it does in man, though it is considerable in the gorilla, and sometimes noticeable γaSimia. Abony meatus auditorius externus exists in all the Simiadoe, and is absent in the whole of the Cebidae. In Nyctipithecus the ali-sphenoid is almost shut out from the parietal by the close approximation of the squamosal to the malar. In Cebus there is often a large malar foramen.

The premaxillary bones have throughout the apes a distinctness of development and a relative size not found in man, the sutures separating them from the maxillaries remaining visible, with the exception of the chimpanzee, after the adult dentition has been attained. The maxil-laries themselves develop great swollen tuberosities in the Cynocephali, and a similar structure is developed even in Macacus niger.

The nasal bones are small, and generally flatter than in man. In the orang they are quite flat. They are convex in some of the Semnopitheci and in the Cynocephali, but the proboscis monkey has its nasal bones no more developed than have other species of its genus. The nasals seem to attain their maximum of relative size in Mycetes.

The lower jaw, or mandible, is always in one piece in adults. It is most man-like in the siamang, since we there alone find a slight chin. On the other hand, in Hylobates the angle is produced downwards and backwards, and we find the same in Hapale. Its maximum of relative size is attained in Mycetes, where the very broad ascending ramus serves to protect and shelter the enormously developed body of the hyoid.

Air cells may be developed, as in the gorilla, in the parts adjacent to the mastoid. Frontal sinuses are generally absent in the Simiadoe, being replaced by a coarse diploe. We find them, however, in the Cebidae, and in Cebus they are often larger than they are in man. The total length of the cerebral cavity is never so much as 2∣ times the length of the basi-cranial axis.

The sutures of the skull become entirely obliterated with age. In the gorilla the sutures assume a more dentated structure than is found in any other ape or in man. The internasal suture becomes early obliterated in most of the Simiadoe. The tentorium is sometimes ossified, as in the Cebinoe and Mycetes. From Hylobates downwards there is a small cerebellar fossa on the inner surface of the petrosal.

The Vertebral Column.

The vertebral or spinal column in all apes consists of the same regions as it does in man, and, with the exception of the coccygeal or caudal portion, these regions bear more or less the same proportions one to another as they do in him. That beautiful sigmoid curvature which exists in the human spine is not found in any ape; but the nearest approximation to it is found, not in the Simiinoe, but in the Cynocephali. In the latisternal apes the spinous processes are directed as in man, but in the rest their apices converge towards a single point in the back.

The cervical region is relatively more elongated than in man in Hylobates, Cynocephalus, and Ateles. The atlas is very man-like in Troglodytes and Simia, except that its transverse process is rather smaller and shorter relatively, and more curved dorsally. Except in Ateles and the Simiinoe, it is almost always perforated by the vertebral artery, instead of being merely grooved by it In Cynocephalus the atlas is exceedingly massive, and may, by very rare exception, develop a spinous process. The spines of the cervical vertebrae do not bifurcate beyond the second, and generally the spine of the seventh vertebra is the longest, at least with the exception of that of the axis. In the gorilla and orang, however, the spines of the third, fourth, fifth, and sixth vertebrae are exceedingly elongated and longer than that of the seventh. The cervical neural laminae are wider antero-posteriorly, the vertebral column being supposed horizontal, in Hylobates and Ateles than in other forma Beneath the anterior articular process (prezygopophysis) a marked prominence—the metapophysis —may be developed, and is particularly conspicuous in Ateles. The costal plate of the sixth cervical is almost always larger than the homologous part in the other cervicals; but it predominates least in the chimpanzee and Nyctipithecus. The length of each centrum, compared with its breadth, is already greater in Troglodytes and Simia than in man. In others the dimensions are about equal, except that in Cynocephalus, Ateles, and Mycetes the length slightly exceeds the breadth.

The dorsal vertebroe vary in number from eleven, as sometimes in Cercopithecus and Macacus, to fourteen, as sometimes in Hylobates, or even to fifteen, as in N^ycti-pithecus. In the Cebidae, above the Hapalinoe, the number rarely falls below thirteen. In the orang the number is, as in man, twelve; in Troglodytes it is thirteen, The proportion of this region does not increase regularly with' the number of its vertebrae. It attains its greatest relative length in Ateles, where it is over nine-twentieths of the total length of the spine without the tail; while in Nycti-pithecτιs it is relatively shorter than in Troglodytes or Simia. The increase in transverse diameter of the bodies of the vertebrae, as we proceed from before backwards, is exceptionally great in Hylobates and Cynocephalus. The lumbar region contains from four to seven vertebrae In the Simiinoe and Cebinoe there are four or five, though in Cebus the number is often six. Its relative length is greatest in Nyctipithecus, Chrysothrix, the Semnopithe- cinoe, and Cynocephalus. It is least in the Simiinoe and Ateles. The number of dorsal and lumbar vertebrae, taken together, is seventeen in Troglodytes and Simia, eighteen (mostly) hi Ateles and Hylobates, and nineteen in the rest. In most forms the dorsal and lumbar regions are about equal in length, but the lumbar region is the shorter in the Simiinoe, and less than half the length of the dorsal in the gorilla. The lumbar spinous processes are vertical, or project backwards in the Simiinoe and in Ateles; in the other forms they project strongly forwards, especially in the lower Cebidae. The lumbar transverse processes always project outwards, more or less at right angles to the axis of the spine, or else forwards. In the Simiinoe and Ateles they are never inclined ventrally, but in some of the lower Simiadoe they begin to be so; in the lower Cebidae they are so very decidedly. Only in Troglodytes and Simia are they inclined somewhat dorsally. In the last two genera the lumbar vertebrae are broader than their length; in most other forms length is in excess. The length of the individual lumbar vertebrae, compared with the dorsal (e.g., the longest lumbar with the ninth dorsal), is greatest in the lower Cebidae, rather less in the lower Simiadoe, and least in the Simiinoe.

The sacrum attains its greatest absolute length in the gorilla, but it is relatively longer than in man in all the Simiinoe. Of all the inferior apes, Hylobates has the relatively longest sacrum. The number of vertebrae inincluded in the sacrum varies more or less with age. In the apes below the Simiinoe there are generally only two or three sacral vertebrae. In Ateles, Hylobates, and Brachyurus, there may be four; while in the Simiinoe there are always five, and sometimes six sacral vertebrae. In most apes the sacrum and lumbar vertebrae appear to lie in one slightly curved line. Troglodytes presents in this respect a great contrast to the human structure. In Simia the sacro-vertebral angle is rather more marked; but sometimes in Cynocephalus it is so much so as almost to rival that of man. The same may be said of the concavity of the anterior surface of the sacrum. It is most marked in the Cynocephali, and is more so in Simia than in Troglodytes. The sacrum gradually tapers posteriorly in Troglodytes and Simia, and more or less so in Hylobates. In the other Simiadoe, however, the sacrum is very wide at its anterior end, and it then very rapidly contracts backwards, so that the transverse diameter of the third sacral vertebra is very much narrower than that of the first. In the Cebidae generally, and especially in Ateles, the contraction is not so marked.

The caudal vertebroe are always more than four in number, except in the Simiinoe and in Macacus inuus. In Cyno cephalus mormon (the mandrill), however, there are sometimes only five vertebrae. The short-tailed Macaci and Brachyuri have from about fifteen to seventeen caudal vertebrae, the shortness of the tail being occasioned rather by a diminution in the size of the component vertebrae than by a decrease in their number. In the other forms the number varies between twenty and thirty-three, the latter being the number attained in the genus Ateles. The proportion borne by this region of the spine to all the more anterior parts is greatest in Ateles, almost three to one; in the other longest-tailed genera it is rarely so large as two to one. The absolute length of the tail is greatest in the Sèmnopithecinoe, where also the individual caudal vertebrae attain their greatest length, namely, two inches. The caudal vertebrae generally increase in length as we proceed backwards from the sacrum, till about the seventh, eighth, or ninth, which, with the tenth and eleventh, are the longest caudal vertebrae in most long-tailed forms. In Ateles, however, it is the eleventh, twelfth, thirteenth, and fourteenth vertebrae that are the longest. In the Simiinoe and in Inuus the caudal vertebrae decrease in length as we proceed backwards. Except in the forms just named, all the first four caudal vertebrae possess a complete neural arch, sometimes six are so provided, but only in A teles does the number attain eight. With the same exceptions, again, the first four caudal vertebrae unite by articular processes, while transverse processes (single or antero-posteriorly double) exist in a great part of the tail. In Ateles the caudal vertebrae are (as might be expected from the very prehensile character of the tail) exceptionally provided with bony processes serving as points of muscular attachment. Chevron bones and processes for their attachment are altogether wanting only in the Simiinoe and in Macacus inuus. They attain their maximum in Ateles, where they present almost every variety of development in one or other part of the caudal region.

Certain vertebral processes, which in man are generally inconspicuous, and which are but little developed in the Simiinoe, attain in lower forms a marked development. These are the metapophyses and anapophyses. The first of these generally appear about the eighth or ninth dorsal vertebra, and may thence be traced backwards into the anterior caudal vertebrae, where they end by coalescing with the prezygopophyses. In Ateles these processes may sometimes be traced as far forward as the third cervical vertebra. The anapophyses become, below the Simiinoe, very conspicuous, projecting outwards and backwards from one vertebra, and embracing the prezygopophysis of the vertebra next behind. Generally they may be traced from the eighth or ninth dorsal vertebra to the penultimate lumbar vertebra. They attain their maximum of relative size in the lower Cebidae. They may (as sometimes in Ateles and Cynocephalus} be traced on to the posterior cervical vertebrae, while they appear to coalesce with the transverse processes in the tail, and thus they may be developed almost throughout the vertebral column. The Cebidae often develop hyperapophyses in the last dorsal and in the lumbar vertebrae. These processes are somewhat similar to anapophyses, but are placed much higher, and each pair embraces the spinous process of the vertebra next behind.

In most apes the sternum is quite narrow, and consists of a more or less enlarged manubrium, followed by a chain of sub-equal and antero-posteriorly elongated bones from three to six in number. In the Simiinoe alone do we find a broad sternum, or one consisting of a manubrium, followed by one bone only, as in Hylobates. The orang presents a singular peculiarity, in that the breast-bone long remains made up of ossifications arranged in pairs, side by side, successively. The total number of ribs has already been indicated in speaking of the dorsal vertebrae. 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. They are 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. Nevertheless, in the Simiinoe, its transverse diameter exceeds its depth by from about one-fourth to a little under one-third of the latter. In Ateles (and sometimes also in Mycetes) the thorax is wider than it is deep, but in all the rest it is narrow, being deeper than it is wide.

The Appendicular Skeleton.

The development of this part of the skeleton has been indicated in a general manner in speaking of the external form. The length of the pelvic limb compared with the pectoral one—the foot and hand being removed—attains in no ape the proportion that it does in man, i.e., 145 to 100; the nearest approximation being made by Nycti-pithecus and Callithrix, namely, about 137 to 100. The length of the foot, compared with that of the hand, is exceptionally small in the Simiinoe, namely, from 84 up to 115 to 100. Its greatest relative length is in Chrysothrix, viz., about 177 to 100. In man it is about 134 to 100. The entire pectoral limb (measured from the summit, of the head of the humerus to the distal end of the longest digit) is absolutely longest in the gorilla and orang. Its proportion to the spine is greatest in Hylobates, where it may attain the proportion of 222 to 100. Next come Ateles 174, Simia 170, the gorilla 150, and the chimpanzee 152. The rest vary from 121 to a little shorter than the spine, except certain of the lower C ebidoe, thus in Chrysothrix and Hapale it is less than 84 to 100. Only in the Simiinoe and in Ateles is the pectoral limb, without the hand, shorter than the spine.

The scapula of the gorilla presents a remarkable likeness to that of man, but that of its congener, the chimpanzee (the posterior vertebral angle being so acute), is less like man’s than is that of the orang. The size of the supraspinous fossa, as compared with the infra-spinous one, attains its maximum in the gorilla and Mycetes. In Simia and the Pitheciinoe the supra-spinous fossa is exceptionally small. The margin, corresponding with the superior margin of man’s scapula, is generally convex in the forms below the Simiinoe (except Ateles and Pithecia), and attains its maximum of convexity in aged Cynocephali. A suprascapular notch is not well defined in the great majority of the Simiadoe, but in some of the Cebidae (Ateles and Mycetes) it is constantly, and in others often, so enclosed as to become a foramen. In Mycetes a remarkable flat process springs from the bridge of bone encircling this foramen. This process exists in no other genus. The surface for the teres major muscle projects out very strongly in the Cyno- pithecinoe and in Cebus and Chrysothrix. The acromion and coracoid processes are short in the lower Simiadoe ; both are long in the Simiinoe and in Ateles.

The clavicle is well developed in every species of the order, and that of the orang is absolutely the largest; and it is longest, compared with the spine, in that animal and in Hylobates, being as 28 or 32 to 100, while in the lower Cebidae it may be less than 12 to 100. This bone is exceptionally slender in Mycetes, and is broadest in Troglodytes and the Cynopithecinoe. In the lower Simiadoe a fossa is excavated beneath the acromial end of the bone. Rarely, as in Simia, there is a very prominent deltoidal ridge.

The humerus presents in all apes the same fossae and prominences as in man. Its length, as compared with the spine, is in IIylobates 70 or 80 to 100; but in most apes its length, thus compared, is between 45 and 30 to 100. The articular surface of the head is directed backwards and inwards, instead of almost exclusively inwards, as in man. In this respect man is most resembled by the Simiinoe. The tuberosities may project upwards slightly above the articular head, as in Cynocephalus. Generally they are about on a level with its top, but may be decidedly below it, as in Ateles, Hylobates, and Simia. The radial border of the bicipital groove may be very prominent, as in Cynocephalus. The groove may be spanned by a bridge of bone, as sometimes in the chimpanzee. The position of the nutrient foramen varies even in different individuals. The supinator ridge is especially developed in Cynocephalus, Cebus, and Hapale. In the Simiinoe it is only slightly developed. The external condyle is distinct in the Simiinoe; in the other genera it is closely applied to the capitellum. A supra-condyloid foramen is never present normally in the Simiadoe, but is present more or less constantly in the Cebidae, from Cebus downwards, being perhaps most frequently absent in Hapale. Through this canal the brachial artery and median nerve pass. The projection of the radial margin of the trochlea is most prominent in the Simiinoe and Hapale. It almost disappears in the Cynopithecinoe. The radius and ulna are never ankylosed together in apes. They diverge most, medianly, one from another in the gorilla. The radius is four-fifths the length of the spine in Hylobates, and three-fifths in Simia and Ateles. Mostly it is between three-tenths and two-fifths of the length of the spine, but may, as in Hapale, be only a quarter. The total length of the radius rather more frequently falls short of, than exceeds, that of the humerus. It exceeds it in Simia, Hylobates, Ateles, Cynocephalus, and sometimes in the Semnopithecinoe. In all the others it falls short—in none, however, so much so as in man, Brachyurus approximating most to the human proportion. The radius is stoutest in Cynocephalus, slenderest in Ateles, and, above all, in Hylobates. The ulna varies, like the radius, in length and breadth. The olecranon is broad in the Simiinoe, but in the lower apes it is relatively larger, especially in Cynocephalus and Mycetes. The styloid process is very long in Hylobates, where it develops a prominence, on its hinder side, for the internal lateral ligament of the wrist. In Ateles this process is extremely long, having, as it were, a rounded articular head placed at the end of a peduncle. The ulna articulates with the carpus in all the apes except Troglodytes and Simia. ]

The skeleton of the hand attains its greatest bulk in the gorilla, but its greatest length in the orang. It may be more than half the length of the spine in Hylobates, and hardly less in Simia and Ateles. It may be but a fifth, as in Chrysothrix.

The carpus consists, in Troglodytes, of the same eight bones as in man. In all the other genera there is a ninth bone, the intermedium. Only in Hylobates does the length of the carpus considerably exceed its breadth—as 100 to 82. The nearest approach to this is made by Ateles, where the length is to the breadth as 100 to 107. The scaphoides may, as in the gorilla and lower Simiadoe, develop a large tuberosity. The intermedium has a flattened proximal surface, which joins the ulnar part of the concave distal articular surface of the scaphoides. Its distal surface is in general deeply concave antero-posteriorly, and embraces the radial side of the head of the magnum. The bone appears to answer to part of the scaphoid of man. The cuneiforme, except in Troglodytes and Simia, articulates directly with the ulna. The pisiforme is small (as in man) in Simia and Ateles; it is very large in the gorilla and Cynocephalus, and long but slender in Hylobates. Commonly it contributes to form, with the cuneiforme, a cup for the reception of the end of the styloid process of the ulna. The trapezium has sometimes, as, e.g., in the gorilla and Hylobates, a very large radial tuberosity. The surface for the reception of the first metacarpal is convex from the dorsal to the palmar surface of the bone, and sometimes it is more or less concave in the reverse direction, but this concavity is never so strongly marked as in man. In ι the highest apes there appears to be much irregularity as to its development In Hylobates there is no trace of any concavity, but a strongly convex and rounded tubercle receives the articular cup of the base of the first metacarpal. In the lower Simiadoe the concavity is sometimes present, and sometimes in the Cebidae (as, e.g., occasionally in Cebus and Brachyurus} a small saddle-shaped surface may be found. In Ateles the trapezium is large in spite of the rudimentary condition of the pollex, but there is no saddle. The trapezium is always so placed that the axis of the convexity of the saddle forms a marked angle with a line drawn across the articulations of the four outer metacarpal bones with the proximal row of carpals. In the gorilla this angle is, as in man, very open; but in the chimpanzee and lower Simiadoe it is smaller, the trapezium being, as it were, somewhat more pressed inwards, at its radial end, towards the middle of the palm. In the American'apes the trapezium is well set out; and this, no doubt, contributes to produce that very feeble opposition and palmad flexion of the pollex which have been noticed as existing in them. The magnum is not generally the largest carpal bone, but rather the unciforme, which latter has its palmar process sometimes very much produced, as is the case in Hylobates. The metacarpus attains its greatest absolute length in the third metacarpal of Simia. This segment may, as in Hylobates, attain the proportion of one-fifth the length of the spine. The metacarpals are longer and narrower proportionally in apes than in man.

The phalanges are the same in number in apes as they are in man, except that in Ateles and Colobus the pollex may have but one small nodular phalanx or none. The phalanges are generally more curved than in man, and, except in the Hapalinoe, the ultimate phalanges are always flattened from dorsum to palm. In the Hapalinoe they are laterally compressed, curved, and pointed to support the peculiar claws of that sub-family. The length of the pollex with its metacarpal bears a much greater proportion to that of the spine in Hylobates and Simia than in man. With the exception of Ateles and Colobus, the shortest thumb, thus estimated, is found in Nyctipithecus and Chrysothrix, namely, 11 to 100.

The pollex without its metacarpal, compared in length with the manus, is shortest (viz., as 17 to 100) in Hylobates, and longest (viz., as 32 to 100) in Hapale. The pollex, when brought beside the index digit, rarely extends so far as in man, and does so only in the Cebidae, where, in the Hapalinoe, it may reach nearly to the distal end of the proximal phalanx of the index. In Cynocephalus it may reach the middle of that phalanx, while in Troglodytes it reaches but very little beyond its proximal end.

The entire pelvic limb, measured from the summit of the femur to the distal end of the longest digit, is absolutely greatest in the gorilla, and then in the orang and the chimpanzee. If the pes be removed, then the leg of the chimpanzee is longer than that of the orang.

Compared with the length of the spine, the entire pelvic limbs of Hylobates and Ateles are longest, namely, as 162 or 169 to 100. That of Hapale is the shortest, being but as 110 to 100. Without the pes, the leg of Hapale is also shortest relatively compared with the spine, namely, as 77 to 100; while that of Hylobates is longest, namely, as 125 to 100. The os innominatum is in every species strikingly different in form from that of man. In absolute size this bone attains its maximum in the gorilla, where it is much larger than in man, and where the ilium is very broad. The external surface of the ilium is generally more or less concave, and concave only. In Troglodytes and Simia, however, it is more or less convex, but not as in man, and therefore there is no sigmoid curvature of the crest of the ilium, and there are no distinct gluteal lines. The internal surface of the ilium is generally narrow and flat, or only slightly concave, except in the gorilla. The tuberosity of the ischium is always a marked and more or less rugose enlargement of the bone; but in the Simiadae below Troglodytes it is flattened and very much developed, and so much everted that sometimes (in Cynocephalus) its transverse exceeds its antero-posterior diameter. In the Cebidae it again becomes small, and more or less rounded.

The spine of the ischium is generally very small, yet distinct. Only in Simia does it attain a considerable sharpness and prominence. The great sciatic notch is never very deep and concave, as in man. It is most concave in the gorilla, the orang, and in Cynocephalus. The lesser sciatic notch is generally represented by a margin which is so slightly concave as to be almost or quite straight save through the eversion of the tuberosity. The projection of the spine of the ischium produces in man a deep notch such as exists in no ape. The cotyloid notch, and the excavation continuous with it, are constantly present, even in Simia, where, however, it is very small and narrow, in harmony with the absence of the ligamentum teres.

The femur's length, compared with that of the spine, is as 67 to 100 in Hylobates, 61 in Ateles, 54 in the gorilla, 47 in Simia. It is shortest in Chrysothrix, 40, and Hapale, 37. Tn the Simiinoe it is shorter than is the humerus, its proportion to which in Simia is as 73 to 100. Only in some of the Semnopithednoe does its length exceed that of the humerus more than it does in man. The shaft of the femur is sometimes nearly straight, as in Hylobates and in most Cebidae. The femur is stoutest, relatively as well as absolutely, in the eorilla. It is slenderest in Hylo bates. The neck of the femur is longest in Simia and Hylobates; shortest in Hapale. Except in the Simiinoe and in Mycetes, the great trochanter is pointed at its upper end. The trochanteric fossa is shallow in the gorilla, but is in most forms deep. The lesser trochanter is at its minimum of relative size in the Simiinoe, and is largest relatively in Hapale, and the posterior surface of the femur is in that genus wide and flat between the trochanters. The pit for the insertion of the ligamentum teres is always present, except in the orang and gorilla, where it is absent almost constantly in the first ape, occasionally in the second. In the Simiinoe, Ateles, and Lagothrix the internal condyle projects considerably further backwards than does the external one. The angle formed by the neck of the femur with the shaft varies from about 155° (Simia) to 128° (the gorilla).

The tibia and fibιda never become ankylosed together. The tibia is absolutely longest in the gorilla. Its length, compared with that of the spine, is never so great as in man, except in Hylobates, in which it is slightly longer relatively. It is shortest in Mycetes, about as 37 to 100. Its length is generally less than that of the femur, but sometimes, in Hapale, it slightly exceeds it. It is never, however, so short compared with the femur as in man. The crest of the tibia is not so sharp as in man. The shaft is sometimes straight, as in Lagothrix and Pithecia, sometimes considerably curved, as in the gorilla and lower Cebidae. The malleolus is generally well-developed, but sometimes, as in the orang, very short. Its articular surface is sometimes nearly at right angles with the inferior surface of the shaft of the tibia, as in the chimpanzee; sometimes it forms an obtuse angle with that surface, as in the gorilla, and still more in the orang. The distal articular surface of the shaft of the tibia is rarely horizontal, as in Ateles and Lagothrix. In the Simiadae and lower Cebidae the outer portion rises so that the articular surface slopes upwards and peronead. The fibula has its malleolus much produced outwards, projecting only about as much as, or rather less than, the tibial malleolus, whereas in man the fibular malleolus is much deeper than the tibial one.

The length of the pes (or foot) is absolutely greatest in the orang and gorilla. Estimating the spine as 100, the length of the pes is as much as 53 in the orang; it approximates to man (35 to 100) most in the lowest Simiadae, and in Chrysothrix —36 to 100. The proportional length of the pes to the rest of the pelvic limb is greatest in Simia (58 to 100), then in Nyctipithecus and Hapale (50 to 100), but never falling quite so low as in man, where it is 30 to 100. Its length, as compared with that of the tibia, is greatest in Simia (122 to 100). In all the rest it is more than four-fifths, except sometimes in Hylobates, which however is never so small as in man, i.e., as 67 to 100. The length of the pes, compared with that of the manus, is greatest in Chrysothrix (177 to 100). In Ateles it sinks to 113 to 100, and in Hylobates to 85 or 84 to 100.

The absolute length of the tarsus is never so great as in man, though that of the gorilla is nearly as long. The rest of the foot is so much longer relatively in apes than in man, that, whereas in him the proportion of the tarsus to the whole pes is as about 46 to 100, it is only 39 to 100 in the gorilla, which in this respect approaches nearest to man. The proportion sinks to 26 to 100 in Simia and Ateles, and 27 or 28 to 100 in Hylobates. Only in Simia and Hylobates is the tarsus ever less, or only a very little more, than twice the length of the carpus. The tarsus consists constantly of the same seven bones as in man, and these bones are so arranged, or bound together by ligaments, as to form a transverse and an antero-posterior arch. In no ape, however, do the distal ends of the inner metatarsals form the anterior point of support of the anteroposterior arch, as in man. The os calcis is always, except in the gorilla, shorter compared with the spine than in man. The tuberosity may be produced upwards or downwards, or both, and is concave or grooved behind, except in the gorilla. In no ape are the long axis of the heel or the peroneal and tibial surfaces of the os calcis so vertical as they are in man; but the bone is always more or less twisted, so that the sustentaculum tali forms a more or less acute angle with the long axis of the tuberosity instead of a right angle, as in man. The twisting of the os calcis is very slight in Simia and Pithecia, and not great in Ateles and Hylobates. It is more marked in the lower Simiadoe, and more so still in Troglodytes. A narrowing of that part, which answers to the plantar surface of man, accompanies this in-twisting. In the gorilla that part of the os calcis which is behind the articular surface for the astragalus exceeds in length all the bone anterior to the hinder border of that surface; and in this respect the gorilla may be said to have the longest heel of any ape, and a longer heel than man. The head of the astragalus is generally united to its body by a tolerably long neck. This neck is, however, in the gorilla shorter than even in man. The upper surface of this bone is less convex than in man, in Simia, Ateles, and the gorilla; generally it is more convex than in man. The surface for the external malleolus forms, with the upper surface of the astragalus, almost a right angle in Hylobates (as in man), and an obtuse one in Ateles and Lagothrix. In most other apes (including Troglodytes') it forms an acute angle. The angle formed by the upper surface of the astragalus with that for the tibial malleolus, instead of being a right angle, as in man, is generally more or less obtuse, especially in the gorilla. The naviculare has sometimes its tuberosity greatly developed; this is especially the case in Hylobates. The surfaces for the three cuneiform bones are generally more convex and concave respectively than in man. The ento-cuneiforme generally has its plantar and distal surfaces considerably longer than its dorsal and proximal surfaces respectively. These are exceptionally equal (as in man) in the orang and gorilla. The surface for the hallux is always strongly convex. The long axis of this articular surface always forms a more or less acute angle with a line drawn across the articular surfaces for the four outer metatarsals. In the lower Simiadoe this angle is as acute as in man. In Troglodytes it is a little more open, but not nearly so open as is the homotypal angle in the hand even of the same species. The surface is never saddle-shaped in apes. In all apes, even in the chimpanzee, the distal tarsal segment is capable, as a whole, of a considerable degree of motion upon the proximal part,— i.e., upon the astragalus and os calcis,—and this mobility is extreme in the orang. The absolutely longest metatarsal bone is the second of Simia. The metatarsus often exceeds the tarsus in length, but it may, as in the gorilla, fall much short of it, thus resembling man. The four outer metatarsals and the innermost one diverge instead of being parallel, as in man. The former, except in the Simiinoe and in Ateles, are more rounded than in man, and their distal articular surfaces are less bent downwards, and are limited posteriorly by a deeper transverse groove. The first metatarsal, compared in length with the spine, is longest in Hylobates (10 or 12 to 100), and shortest in Hapale (about 6 to 100). It is always longer than the first metacarpal, except in Simia. Its proximal surface is generally more concave than in man, and its long axis is different. It is as if the metatarsal of man had been removed, softenèd, and then, after being turned, so that the dorsum looks inwards as well as upwards, reapplied to the convex ento-cuneiforme, and thus stamped with an oblique depression. The angle formed by this surface, with a line traversing the articular heads of the four outer metatarsals, approximates to a rectangle instead of to a straight line, as in man.

The phalanges are always the same in number as in man, except that the hallux of Simia has often but one. They are very like their homotypes in the manus, and are convex above, concave and flattened below. Only in the Hapalinae are the last phalanges laterally compressed instead of flattened. The pedal digits are never nearly so short relatively in apes as they are in man; yet the proportion borne by the hallux, with its metatarsal, to the spine closely approximates in the gorilla to the proportion existing in man, and the proportion is exceeded in Hylobates and Ateles. It is much in defect in Hapalinae, where it is little more than one-tenth. Its proportion to the whole pes in Hylobates (as in man) is nearly half, while in Simia it is but a quarter, and but little more in the Hapalinae and the Semnopithecinoe. The hallux, when brought beside the second digit, never reaches so far as in man, but at most (as in the chimpanzee) to the proximal end of the second phalanx, or to the middle of the proximal phalanx (as in most Cebidae), or a little beyond its base (as in Hapale and the Semnopithecinoe), or not nearly even to the distal end of the metatarsal (as in Simia). Except in Simia and some Cebidae, notably Hapale, the hallux projects further than does the pollex of the same individual when applied to the second digit of the manus. The hallux also always exceeds the pollex in absolute length, except in Hapale and Simia. The length of the hallux, without its metatarsal, compared with that of the spine, is as 25 to 100 in the chimpanzee (as in man), 19 in the gorilla, and but 8 in Simia. The second digit of the pes is always longer than that of the manus except in the Simiinoe, which so far resemble man. The index digit, with its metatarsal, compared -with the spine, is as 38 to 100 in Simia, and it varies thence down to 21 in Cercopithecus. The longest digit of the pes always exceeds that of the manus, except in the Simiinoe and Ateles. The Muscles.

The muscles of apes are very similar in number, distribution, and form to those of man, except that in the long-tailed forms (e.g., Semnopithecus) the muscular bundles answering to the coccygeal muscles of man are so greatly developed as to form eight sets of caudal muscles. The latissimus dorsi commonly sends on a slip, called the dorso-epitrochlear, as far as the olecranon. Often there is a rhomboideus capitis, and a muscle, called levator claviculae, almost always descends from the cervical transverse processes to the outer part of the clavicle. The flexor longus pollicis and the flexor digitorum profundus are always more or less united. The extensor indicis commonly sends a tendon to the third digit as well as to the index, and at the same time the extensor minimi digiti sends a tendon to the fourth digit as well as to the fifth. An extensor primi internodii pollicis is never developed, but the extensor ossis metacarpi pollicis is often doubled, even in the chimpanzee. In the orang the flexor longus pollicis sends a tendon only to the index. In Hylobates the supinator longus is inserted into the middle of the radius, and there is an abductor tertii internodii indicis going from the metacarpal of the index to its ungual phalanx. Often the extensor brevis pollicis and the abductor longus become more or less united. In spite of the rudimentary condition of the thumb in Ateles, its muscles exist, though in a rudimentary condition, but in Hapale the opponens pollicis is wanting.

The lower limb in the orang generally wants the ligamentum, teres, which seems to be sometimes absent in the gorilla also. The glutaei muscles of apes are feeble and small, and are inserted low down on the femur. Only in the gorilla are they large enough to cause a small buttock to protrude over the ischiatic tuberosities, but even in this ape the buttocks do not meet so as to conceal the anus. Apes have an extra muscle, called the scansorius, which passes down from the edge of the ilium to the great trochanter of the femur, and must act as a powerful rotator of the thigh inwards. The gracilis is much broader than in man, and is inserted lower down on the tibia than in him, as is also the case with the semi-membranosus and semi-tendinosus. The short head of the biceps femoris is generally wanting. The gastrocnemei and soleus are flatter than in man, and the latter has only a fibular origin. In the lower Simiadae the plantaris passes over the pulley-like end of the os calcis, and goes to the plantar fascia. No ape seems to have any peroneus tertius, but we may find even in Semnopithecus a slender peroneus quinti digiti passing behind the outer malleolus, and going to the metatarsal of the fifth digit, while in the Cebidae we may also have a peroneus quarti digiti going similarly to the fourth digit. The tibialis anticus may be divided, as even in the chimpanzee, like its homotype the extensor ossis metacarpi pollicis. The muscles of the foot, with the exception of the interossei, resemble the muscles of the foot of man, and not those of his hand. As regards the interossei even, the difference is very slight. It consists in the insertion of the tendon of that dorsal interosseous mass which is interposed between the second and third metatarsals, into the proximal phalanx of the third digit (as in the human hand), instead of into that of the secpnd digit (as in the human foot). The hallux in the orang is, in spite of its imperfect development, provided with an opponens muscle. The flexor brevis digitorum pedis does not, in apes, arise exclusively from the os calcis, and the flexor accessorius arises from the surface of the deep flexor tendons. The last named muscle may be wanting, as sometimes at least in Hylobates. A muscle, called the abductor ossis metacarpi quinti, exists even in the chimpanzee. In the lower Cebidae, and especially in the Hapalinoe, the interossei become true flexores breves, and altogether cease to be visible on the dorsum of the foot.

The Bkain.

The absolute size of the brain never in any ape approaches that of man. Thus 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 27∣ 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 basi-cranial 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 Simiadae the posterior cornu is relatively shorter than in man, it again becomes elongated in the Cebidae, 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 are 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 Troglodytes, on the contrary, it is very richly convoluted. A hippocampus minor is present in all apes, and in some of the Cebidae it is much larger relatively than it is in man, and is absolutely larger than the hippocampus major. Of all apes, the orang has the 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 Troglodytes, 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 Cebidae than in the Simiadae. In all apes below the Simiinoe, 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 Cebidae. The Teeth.

The teeth of apes consist, as in man, of incisors, canines, premolars, and molars; but the series of teeth nowhere forms so perfect an arch as in man, the opposite series of grinding teeth tending to become more parallel. No ape has the teeth placed in one uninterrupted series in each jaw, as is the case in the human species, but there is always a small interval (diastemei) between each upper canine and the adjacent incisor, and between each lower canine and the adjacent premolar. This condition is due to the excessive size of the canines, the interspaces giving passage to the apices of these teetE . This prolongation of the canines into tusk-like weapons of offence and defence (especially developed in the males), makes a great difference between the aspect of the dentition in apes and man. The number of the teeth is the same as in man in the Simiadae. The Cebidae have an additional premolar on each side of each jaw, and the Hapalinae, besides this, have a true molar the less. The incisors are always nearly vertical, save in the Pithednae, when their apices project strongly forward. The canines are always considerably longer than the incisors, except in the genus Hapale, where the lower incisors equal the canines in length. The premolars differ structurally from the molars much as in man, save that the first lower premolar may be modified in shape to give passage to the upper canine, as is specially to be seen in Cynocephalus. The grinding surface of the molars consists generally of two transverse ridges, each end of each ridge projecting more than the intermediate part, and so giving rise to four tubercles. In Simia and Troglodytes, however, we find in the upper molars an additional structure, which also exists in man. This is a ridge which runs obliquely from the front inner tubercle (or cusp), outwards and backwards to the hind outer tubercle. In the rest of the Simiadae this ridge is wanting, but it reappears in Ateles and Mycetes amongst the Cebidae. In the Hapalinoe the tubercles of the molars are more produced and sharp-pointed, in harmony with their decidedly insectivorous habits. The last lower molar may be reduced or much enlarged as compared with the others. Thus in Cercopithecus talapoin it has but three tubercles, while in the Macad and Cynocephali it is very large, and has five well-developed cusps. The number of milk teeth is as in man, save that the Cebidae have an additional milk molar. In general the canines are the last teeth to be cut of the permanent dentition. Their cutting sometimes causes such constitutional disturbance as to produce convulsions and death. In the gibbons, however, the canines accompany, if they do not precede, the appearance of the hindmost molar, while in the orang they at least sometimes make their appearance before that grinder.

Organs of Nutrition and Excretion.

The alimentary, circulating, and excretory organs of apes closely resemble those of man. The mouth is always guarded by lips, which, though generally thin, are often very mobile and extensible, the lower lip having no fraenum in the orang, and this is also absent in Cebus, though it may be present in other forms, as, e.g., in Troglodytes and Cynocephalus.

The tongue is much longer relatively in most apes than in man; but it may closely resemble his, as does that of the orang, in which the circumvallate papillae are collected in a V-shaped aggregation, while there may be only two such papillae, as in Cynocephalus and Ateles. In Hylobates the tongue is in this respect man-like; yet in that genus we first meet with a sub-lingual process (which becomes much larger in the lower apes), in the form of a little conical bifid membrane. This structure is formed by the union of the processes upon which open the sub-maxillary ducts—processes much elongated in the chimpanzee, though man-like in the orang.

The uvula is generally present, but becomes rudimentary in the Cebidae generally, though it exists as a relatively thick, short structure in Hapale. It is long and pointed in Semnopithecus, and plainly visible in Hylobates and Troglodytes. On the other hand, in Simia it is disguised by the extensive development of the membranous edge of the velum palati on each side of it.

The stomach is simple in all the apes except the Semno-pithecince. It is especially human in shape in Hylobates, except that the pylorus is somewhat more elongated and distinct. It is of a rounded form in Pithecia, and in Hapale the cardiac orifice is exceptionally near to the pylorus. In the Semnopithecinae the stomach is extremely sacculated, especially at the cardiac end, being, in fact, very like a colon spirally coiled. It is in the stomach of these apes that the oriental Bezoar stones are found.

The intestine in apes is devoid of valvuloe conniventes, but is always provided with a well-developed caecum, though it is short and conical in Cynocephalus. Only in the Simiinoe do we find a vermiform appendix.

The colon may be much longer relatively than in man, as in Simia and Troglodytes. It may be greatly sacculated, as in Hylobates; or devoid of sacculations, as in Cebus. As in foetal man, so in the lower apes, only the right extremity of the mesocolon is involved in the formation of the great omentum, the middle and left parts of the mesocolon lying behind, and independent of the omentum. This is not, however, the case in the Simiinoe, which are more like adult man in this respect.

The liver may be very like man’s, especially in Hylobates, the orang, and the chimpanzee; but in the gorilla both the right and left lobes are cleft by a fissure almost as much as in Cynocephalus. In the Semnopithecinae the liver is much divided, and it is placed obliquely to accommodate the sacculated stomach. The lateral lobes of the liver are in Hapale very much larger than the central lobe. The caudate lobe is very large in the Cebidae, especially in Ateles, and above all in Pithecia. There is always a gallbladder.

The larynx, is in many apes furnished with sac-like appendages. These are different in different species as regards number, size, and situation. They may be dilatations of the laryngeal ventricle (opening into the larynx below the false vocal chords), as in Simia and Troglodytes. They may open above the false vocal chords so as to be, in fact, 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 Simiadae below the Simiinoe. There may be a single median opening at the back of the trachea, just below the cricoid cartilage, 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 axillae, as in the gorilla and orang. A sac may occupy the cavity of the expanded body of the hyoid bone, as in Mycetes.

The os hyoides 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 cornua of the hyoid 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 they may even be jointed structures, as in Lagothrix.

The lungs have generally the form of those of man; but the right lung may have four lobes, as, e.g., in Hylobates.

The great arterial trunks in Simia and Troglodytes are arranged as in man. In Hylobates and the lower apes, however, the left carotid may take its origin from the innominate artery.

The Generative Organs.

The generative organs are, in common with the other parts of the body, formed on the same model as in tho human species. The penis is pendulous, i.e., hangs freely, instead of being (as in the dog) bound to the ventral surface of the abdomen. The prepuce, however, is without a fraenum. The testes are relatively large, and descend into a scrotum. In some species, however, they do not descend so much as they do in man, but remain just outside the inguinal ring, and are thus placed rather beside than beneath the penis. These parts, as has been said, are brightly coloured in some of the lower Simiadae. The penis is furnished with a bone in all the apes below the Anthropoid ones, and probably in the latter also, since the chimpanzee has one about one-third of an inch long and gristly at each end. In all apes the uterus is single, and not twohorned; but it is more elongated relatively in monkeys than in the human species. The clitoris is well-developed, but boneless in the Simiadae, and is large even in Troglodytes niger. In the Cebidae it contains a bone; and in some genera, especially in the Cebinoe, it is enormously developed, so as to be very easily mistaken for a penis. In Ateles, however, its length is mainly due to its extremely elongated prepuce.

The placenta of apes is discoidal and deciduate, and is generally bilobed. Sometimes, however, as in Mycetes, it is single. It is especially thick in proportion in the Hapalinoe. In the Simiadae there is but one umbilical vein, but in the Cebidae there are two.

Gestation in the lower Simiadae lasts about seven months, but in the Hapalinae only three months.

Menstruation occurs periodically, but the excretion is less sanguineous than in the human species. In the lower Simiadae it is chiefly manifested by a turgescence of the external organs, which may extend widely in the parts adjacent, and even beneath the tail.

Lactation lasts, in the better known forms, for an average of six months, and the young are carried at the breast in a very human attitude,

DISTRIBUTION IN TIME.

There appears as yet to be no evidence of the existence of apes earlier than during the Miocene period. This absence of evidence must by no means be taken as a conclusive proof of their non-existence, since, as Dr Falconer has pointed out, we ought not to expect to find ape fossils often. We ought not to expect this, because the agility and arboreal life of these animals enable them to escape local inundations, and other causes of destruction and speedy burial, to which more sluggish and terrestrial animals are exposed. When they fall dead they are almost immediately devoured by carnivorous animals and feeders on carrion, and it is owing to this that their remains are so rarely found in India, on which account the Hindoos believe that they bury their dead.

Two teeth found in Suffolk were at first described by Professor Owen as those of apes, under the title Macacus eocaenus. This opinion, however, he has since withdrawn.

A fragment of a right, maxilla, from Soleure in Switzerland, was described by Rütimeyer in 1862, under the name Coenopithecus lemuroides. But the recent discovery of fossil lemurs in France renders the ape character of this fragment (which was always doubtful) still more uncertain.

When we enter upon Miocene deposits we find plentiful and unquestionable remains of apes now extinct. In India, in the Sewalik hills, the astragalus of a Semnopithecus (resembling S. entellus) has been found. Also jaws and teeth of other forms allied to Semnopithecus and Macacus have been discovered, one with an upper jaw nearly as large as that of the existing orang. These fossils, however, exhibit no remarkable difference in form from the bones of existing apes.

In Europe a very remarkable ape fossil, named Dryo∙ pithecus fontani (Lartet), has been found at Saint Gaudens in France. A lower jaw and humerus were there obtained, but isolated teeth have also been met with in the Suabian Alps. This creature was an ape belonging to the highest sub-family, Simiinoe, and was allied to Hylobates, but ef greater bulk than any existing gibbon.

Two other species of ape have been found allied to Hylobates, but of smaller size than Dryopithecus, and showing some probable affinity to Semnopithecus. These are Pliopithecus antiquus (Lartet), and P. platyodon (Biedermann). Of the former, two imperfect lower jaws were found in fresh-water deposit at Sansan, near Auch, in France; while of the latter, an upper jaw has been found in Zurich at Elgg, in the upper fresh-water Molasse there. Another ape (probably of the Simiinoe'), of which a lower jaw has been found in the lignite bed at Monte Bamboli in Tuscany, has been named by G. Μ. Gervais, Oreopithecus bambolii.

Μ. Gaudry has also found a rich deposit of ape relics at Pikermi in Greece. He has sent thence to Paris parts of as many as twenty-five individuals, while other remains are preserved in Munich, and no less than five crania at Milan. These remains have been placed by Wagner in a new genus, Mesopithecus. They are very interesting, as showing a somewhat intermediate structure compared with living apes. The cranium and dentition bear affinity to Semnopithecus, but the limbs are rather those of Macacus.

Certain fragments found at Eppelsheim (in strata of the same geological age as the Pikermi deposits) have also been attributed to the former genus; while five mandibula, found at Steinheim in Würtemberg, have received the name, from Fraas, of Semnopithecus grandaevus.

Amongst the rich palaeontological treasures which have recently been found inthe North American Miocene deposits are certain teeth and fragments, which, it has been suggested, may be those of apes. At present, however, their nature is quite problematical, though the presence of apes at that period in America would be a fact of extreme interest, if sufficient remains could be found to determine whether such apes were Simiadae or Cebidae, or forms intermediate between the two.

The Pliocene deposits have not yet yielded much in the way of ape remains. Some teeth from Montpellier (found in fresh-water marl) have been named Semnopithecus Monsq>essulanus by Μ. Gervais, while part of a lower jaw from the same locality has been called Macacus priscus. Other fragments of jaws, and some teeth of Macaci, have been found in the Val d’Amo, and are preserved at Pisa, Turin, and Florence. A single tooth from Grays, Essex, has been described by Professor Owen as Macacus plio- caenus.

In America, besides the Miocene fragments before referred to, numerous bones of Mycetes and other genera have been found in the caves of Brazil. These, however, appear to be, geologically speaking, quite recent, and they closely resemble the bones of apes now living in that region.

For further details as to fossil apes, an article may be referred to (a translation from the Italian) by Major Forsyth, in the Annals and Magazine of Natur cd History, for the month of September 1872.

GEOGRAPHICAL DISTRIBUTION.

The apes are, as far as is yet certainly known, at present almost confined to tropical latitudes. Theiι-most northern limits in the Old World are Gibraltar (Macacus inuus), Moupin, in Thibet (Macacus thibetanus and Semnopithecus roxellanae), and Japan (Macacus speciosus). In the New World the highest northern latitude certainly known to be attained is 18° or 19° (Ateles melanochir) in Southern Mexico, but they possibly reach even latitude 23°. Father David, however, sees no reason (considering the severity of the climate of Moupin) why apes should not also be found in the mountains of Northern China, and the natives have repeatedly assured him they are to be found there. Southwards, apes are found to near the Cape of Good Hope, and the island of Timor (Macacus cynomolgus), in the Indian Archipelago, in the Old World, and to about 30° in Brazil and Paraguay, in the New World. As to vertical extent, a Semnopithecus has been seen near Simlah, at a height of 11,000 feet; Dr Hooker saw monkeys in the Himalaya at an elevation above 8000 feet; and Semnopithecus roxellanae and Macacus thibetanus were found by Father David inhabiting the Snowy Mountains of Moupin, in Thibet, at an elevation of about 3000 metres, where frost and snow last several months. In Miocene times the ape range was more extensive—namely, to Greece, Tuscany, the South of France, Zurich, Würtemberg, and even to Essex.

Some of the localities richest in monkeys are islands, such as Ceylon, Borneo, Sumatra, and Java; and apes are also found in Trinidad, and the island of Fernando Po.

There are, however, certain islands which seem eminently well suited ⅛o support an ape population, where apes, nevertheless, are conspicuous by their absence. Such are the West Indian Islands, Madagascar, and New Guinea; moreover, no ape inhabits tropical Australia. These facts become the more remarkable, if, as Father David suspects, apes exist in Northern China to-day. Evidently it is not climate which prevents their existing in Central Europe now. The continents of Africa, south of the Sahara; of Asia, south of the Himalaya; and of America, from Panama to the southern part of Brazil, are, with the islands before mentioned, the special ape regions of the existing fauna.

There is a remarkable difference between the ape population of the New and the Old World, the latter being inhabited exclusively by Simiadae, the former as exclusively by the Cebidae. Europe has but a single ape species; and Asia, north of the Himalaya, has but the few found in Thibet, China, and Japan. Africa, north of the Sahara, is zoologically a part of Europe, and there also Macacus inuus is found, which is the only African species of the genus. African apes are the chimpanzee and gorilla of the west coast, the former extending eastwards to 28° E. long.; the Colobi (which are, in fact, but the African form of Semnopithecus), the long-tailed Cercopitheci, including mangabeys (or white-eyelid monkeys); and, lastly, the baboons, Cynocephali. The genus Cynocephalus extends into Arabia; but that, zoologically speaking, is a part of Africa. The Asiatic regions possess the orang (Simia) (in Borneo and Sumatra), the long-armed apes (Hylobates), the Semnopitheci, and Macaci.

One form of Macacus, and a very peculiar one (Μ. niger), is found in the islands Batchian and Celebes; and it is a noteworthy fact that this, the most baboon-like of all the Macaci, should only exist in a region so extremely remote from Africa. The genus Macacus is the most widely spread of any existing genus—namely, from Gibraltar, North Africa, Thibet, and Japan (perhaps even from Northern China), down to the island of Timor, and from the north-west of Africa in the west, to Batchian, Japan, and the Philippine Islands in the east. In ancient times this genus seems to have extended to France, and even to Essex. It is interesting to note that, in the Miocene period, the geographical range of the apes of India was much greater. Gibbon-like monkeys existed in the south of France, while forms intermediate between Semnopithecus and Macacus abounded in Greece.

In America, north of Panama, the genera as yet 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, of course, the headquarters of the American apes; but different portions of that vast region have a somewhat different 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 furthest; but they do not probably all extend to the furthest limit yet known, namely, 30° S. The species found farthest south are Mycetes caraya, Cebus fatuellus, and Callithrix personatus.

ZOOLOGICAL POSITION AND AFFINITIES OF APES.

By universal consent apes are placed in the highest rank of all brutes, and, excepting man, are generally taken to be the most perfect animals of the mammalian class. It may be questioned, however, whether, if the animal man had never existed, this place would be assigned them by any observing intelligence. The half-apes, or lemurs, commonly placed in the same order with them, are certainly inferior mammals; and it might be contended that the perfection of the mammalian type is rather to be found in the Felidae (or cat family), by reasoning analogous to that by which it might also be contended that birds (with their differentiated limbs, perfect circulating and respira tory systems, acute sense organs, complex instincts, and teachableness) are really the highest of all vertebrate animals, and represent the vertebrate type of structure carried to the highest degree of perfection yet attained.

The question as to which animals are most nearly allied to apes is one by no means easy to answer. Leaving man aside (whose close anatomical resemblance to apes is so obvious), it is at present extremely difficult to say what are the apes’ true zoological affinities. It is to be hoped that future palaeontological researches may afford us materials for tracing these out; but at present a chasm separates the apes from every other group of animals. The halfapes, or lemurs, were generally considered to lead down from the apes towards the Insectivora, and thence to the implacental mammals; but the differences between the apes and lemurs are so many and great, that it cannot be considered otherwise than in the highest degree improbable that (on the Evolution hypothesis) they took origin from any common root-form that was not equally the progenitor of other mammalian orders.

But if the apes cannot be considered to show evidence of genetic affinity with any other mammalian order, do they constitute so homogeneous a group as to suggest the former existence of one ancient root-form common to them all? To this question it may be answered that the differences between the Simiadae and Cebidae are such as to render it doubtful whether they may not have had respectively quite different origins, and whether their resemblances may not have been superinduced by similarity of needs and conditions. The differences referred to are as to— (1), dentition; (2), nasal septum; (3), tail—the Cebidae showing a tendency to a curled tail-end, while the Simiadae never manifest any such tendency; (4), cheek pouches; (5), ischiatic callosities; (6), general form and habit of body; (7), opposability of the thumb; (8), bony meatus auditorius externus. All these characters, taken together, seem to make it probable that the Cebidae and Simiadae are not diverging offish ots from some common ape parent, but that they have arisen in an independence as complete as that between the origin of either of them and the origin of the lemuroids or carnivores. Possibly further discoveries in the Miocene deposits of North America will reveal to us transitional forms between the Old and the New World apes, but the existence of such forms cannot certainly as yet be affirmed. It may be asked, however, Can the genera, which possess so many points in common as Cebus and Cercopithecus, have come to resemble each other independently J To this it may be replied, that the number of similarities of structure which must have had an independent origin is so great that it is difficult to see why those of the two genera named may not also have had such an origin. As examples of such similarities of independent origin, the following structures may be referred to :—The bony covering of the temporal fossa in Chelonia, Pelobates, and Lophiomys; the compound tooth structure of Orycte-ropus and Myliobatis; the coexistence of a certain form of dentition with a saltatory habit in Macropus and Macrosce-lides; the presence of but eight carpal bones in Troglodytes and Indris; the course of the vertebral artery in Auchenia and Myrmecophaga; the flying membrane in certain squirrels and phalangers; the canines and premolars of Canis and Thylacinus; the grinders of Peromeles and Urotrichus; the external form and habit of body of Mus, Sorex, and Antechinus; and the peculiar dorsal shields in tortoises and certain frogs. But if some naturalists are disposed to admit that the common origin of the Cebidae and Simiadoe may be very doubtful, can they be even sure of that of Cercopithecus and Hylobatest It has been recently suggested, that the Artiodactyla and the Perissodactyla (the even and the odd-toed ungulates) may be genetically independent (their common characters being merely adaptive, functional ones), as also with the Baloenoidea (whales), and Delphinoidea (dolphins). The response of organisation to need being such as it is (structure and function manifesting themselves so simultaneously), the discrimination between genetic and adaptive characters must always be a work of extreme delicacy. In the presence of the various genealogical trees of animal descent which have been so hastily put forward of late, a judicious scepticism seems the attitude best warranted by the evidence yet obtained. If so many similar forms have arisen in mutual independence, then the affinities of the animal kingdom, or even of the mammalian class, can never be represented by the symbol of a tree. Rather, we should conceive the existence of a grove of trees, closely approximated, greatly differing in age and size, with their branches interlaced in a most complex entanglement. The great group of apes is composed of two such branches; but their relations one to another, to the other branches which represent mammalian groups, and to the trunks from which such branches diverge, are problems still awaiting solution. .

There can, however, be no doubt that the Simiadoe and Cebidae together form a most natural group, and are closely allied with man in structure. Moreover, as man is the highest animal, and, zoologically considered, differs less from even the lowest ape than such ape differs from any other animal, man and apes must be placed together in one order, which may well bear its primitive Linnean name, “Primates.” Whether any other animals (and, if any, what) should also be included in this order, are questions for the consideration of which the reader is referred to the heading Mammalia. [table] [table]

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