Handbook to the Primates/Cebinae

We now come to describe the remaining Monkeys of the New World. The Cebinæ are characterised by having the incisors vertical, not procumbent; they have no inflated hyoid bone as in the foregoing Sub-family. The tail in all is long and prehensile, although in some species it is a less perfect grasping organ, being clothed with hair to the tip, instead of being there naked and highly sensitive. The thumb may be present or absent.

This Sub-family contains four genera: the Capuchins (Cebus); The Woolly Monkeys (Lagothrix); the Woolly Spider-Monkeys (Eriodes); and the Spider-Monkeys (Ateles). The species belonging to these genera are very numerous, and are found over the whole region from Mexico in the north, to Paraguay and Bolivia in the south, or from about 25° N. lat., to 30° S. lat.

This is the typical genus of the American Monkeys. They are distinguished by having a robust body, covered with woolly fur, with a rounded head and a face which, instead of having a protruding muzzle, is more erect and Man-like. They are the commonest Monkeys seen in captivity in our streets. Their tail is long and covered with hair to the tip, and, though prehensile, it is not the perfect substitute for an additional hand noticed in several other genera. Their limbs are only moderately long, and are less slender than in the Spider-Monkeys. The fore-limbs have a well-developed thumb, which, as compared with the length of the hand, is the most Man-like of all the Apes; in some species the nails of the digits are compressed laterally.

In the skull the cranial portion exceeds the facial. Professor Mivart observes that in this group the facial part is relatively smaller than in many of the higher Old-World Apes. The skull has no external bony canal (or meatus) to the ear; and its frontal bones possess large air-cavities. In the Capuchins the incisor teeth are erect, and are always shorter than the canines. The molars are four-cusped, and have, on their crowns, two transverse ridges and the oblique ridge, already described in the Lemuroidea, from the front inner cusp to the hind outer cusp. These animals have also one milk-molar tooth more than in Man.

The outer surface of the main brain (cerebrum) is almost as much convoluted as in the Old World Apes.

The Capuchins range from Costa Rica to Paraguay, and are represented by about eighteen species. They are very gentle and docile animals.

F. Cuvier observes in his "Histoire Naturelle des Mammiferes," that of all the Quadrumana—indeed, of all the Mammals—there are none so difficult to characterise as the Capuchins of America, whose colours vary almost with every individual. No two authors agree in the number of species the genus contains. Brisson recognised three, Linnæus four, Gmelin six, Buffon two, and George Cuvier supposed it possible that they all belonged to but one species. Two causes help to produce this diversity of opinion; one is, as remarked above, the natural disposition which these animals have to vary, and to become lighter or darker in colour according to circumstances, and the other is the extremely close relationship that exists between the different species of the genus. Observations, however, are not yet numerous enough, nor exact enough, to enable those who have only studied the species alive in Europe, or had skins, to decide with such imperfect data as to their sex, age, and habitat. Not until some naturalist has made a prolonged study of these animals in their native country, and watched their conduct and relations in the living state, can we hope to attain to any certain knowledge of how many species the genus contains; and of the differences between the old and young of both sexes at different periods from youth to age.

Characters.—Hair very silky, smooth and stiff, and thicker above than below. Face and forehead nude, flesh-coloured; hands and feet nude, of a violet hue, as also the thinly-haired skin of the under side of the body. The tip of the tail for a short distance being naked, distinguishes this species from all others. Shoulders, arms, and sides of the head behind the ears pure white; chest and throat yellowish; rest of the body deep black.

Older individuals have the head longer than the younger ones, and the shoulders yellowish instead of white. Length of the body, 13½ inches; of the tail, 17 inches.

Distribution.—This species was discovered by Humboldt in the low lands of Colombia. From Colombia its range extends north to Nicaragua. It has been obtained in Veragua, in Panama, in Costa Rica, and in the north-east of the country between the Pacuar and Chirripo rivers, and also on the mountains of Candalaria.

Habits.—The White-throated Capuchin feeds partly on fruit, as Mr. Belt has narrated in his well-known "Naturalist in Nicaragua." He adds:—"It is incessantly on the look out for insects, examining the crevices in trees and withered leaves, seizing the largest beetles and munching them up with the greatest relish. It is also very fond of eggs and young birds, and must play havoc amongst the nestlings. Probably owing to its carnivorous habits, its flesh is not considered so good by Monkey-eaters as that of the fruit-eating Spider-Monkey; but I never myself tried either."

Mr. Salvin saw a troop of these Monkeys in company with several Spider-Monkeys by the margin of a watercourse in Nicaragua, and remarked that the actions of the latter were bolder and more active than those of the Capuchins, which were slower and more timid.

According to Cuvier, the cry of this animal in captivity is a continuous soft whistle until its wants are satisfied; if it wants nothing this whistle is intermittent, and very soft. When in terror, its cry is a veritable bark, broken by silent intervals.

It is extremely docile and very intelligent; the look in its eyes is remarkably penetrating, and it appears to read in the eyes of its observer what is passing within him, and to comprehend every motion and gesture.

When pleased it utters a reiterated shrill note, and draws back the corners of its mouth, producing a smile by contracting the same muscles as in the human face.

Characters.—Fur soft, elongate, silky, with thick under-fur. Hair on front of head elongate and reflexed, forming across the brow a short crest, higher above each eye; hair on top of head lying flat; that on cheeks short and adpressed; base of nose large, and corrugated longitudinally; toes long; tail longer than in other species; under surface of body less haired.

General colour silky brown, almost black on the head and limbs, paler on the shoulders and arms; the whiskers forming a white, or sometimes pale yellow, band, bordering the cheeks from opposite the eyes to the chin. Face and hands naked, violet; skin below the hair of the same colour.

The hair of the body is longer in winter than in spring; but the crests, or "horns," and the white whiskers appear only when the animal is fully adult.

Distribution.—Brazil.

Characters.—Hairs of crown short and reflexed, forming a small short crest, separated by a median furrow on each side of the dark crown patch. Fur soft; the coronal patch on the back of the head small, black or brown; crest black.

General colour golden fulvous or greyish fulvous; limbs and tail dark brown; beard golden-red.

Varieties of this species are sometimes entirely fulvous, with the forehead white; others are entirely albino.

Distribution.—Bolivia.

Characters.—Fur soft and stiff. Head large and round covered with short recumbent hairs. Face naked, pale round the prominent eyes; muzzle sharp, and of the same colour as that which surrounds the eyes; forehead, temples, throat, chest, under surface of body, sides of jaws, and front of arms, pale orange-yellow; outer side of arms, pale orange, washed with white; fore-arms, rump, hind-limbs, and tail black; a mixture of black and brown, expanding irregularly into spots on the yellow, covering the back, shoulders, and sides of body; a spot on the crown, black; a superciliary ridge forming a band of whiskers extending down the cheeks, and meeting under the chin, also black. Hands naked, violet, almost black.

Varieties occur with the shoulders and loins pale yellow, instead of mixed black and brown, and the outside of the thighs and the base of the tail, reddish. In some specimens the pale yellow of the back gives place to a white ground.

Distribution.—Rio de Janeiro, Brazil; Paraguay (?); Guiana.

Habits.—Little is known of the habits of this species; but F. Cuvier, who had one under his care in the "Ménagerie Royale," in Paris, remarks that it had the confiding disposition characteristic of the Capuchins, although very timid. It exhibited a great desire to be caressed, was very affectionate and most intelligent. Its physiognomy, however, he says, was involuntarily repellent, being one that, among ourselves, would indicate a person steeped in ignorance and sensuality.

SMOOTH-HEADED CAPUCHIN.

Characters.—Fur thick, harsh; hair of crown short, reflexed; on the sides of the crown a dark spot, elongated and elevated into two longer or shorter crests, according to the season and the age of the animal. General colour reddish-brown, darker on the hind-limbs, tail, and middle of the back; fore-arms, crown-spot, and whiskers, black; front of shoulders greyish or yellow; Face naked, purplish flesh-colour.

This species is subject to great individual variation. Its general colour is sometimes pale yellowish, with the whiskers yellow.

Distribution.—Brazil; Guiana, near the coast; on the mountains of the Upper Magdalena Valley; Tolima, U.S. Colombia, from 5,000 to 7,000 ft.

Habits.—This species, called "Mico Maizero" by the inhabitants of Tolima, lives as all the Cebi do, in considerable troops in the forests. When wild, it is restless and destructive, but in captivity it is docile and affectionate.

Characters.—Head round; muzzle protruding. Fur black, ringed with golden-yellow; under side of body rufous. Hairs of back brown at base, red higher up, black at the tips.

Distribution.—Brazil.

Characters.—Head round; hairs of crown short and reversed, sometimes elongated into two retrorsal tufts. Fur short, close, and in general colour maroon, turning to black, darker on the under surface; face, chin, sides of forehead and a streak above the eyebrows, yellowish-white.

Distribution.—Lower Amazon region.

Habits.—Little is known of this Monkey beyond what Mr. Bates has told us, viz., that it is a great depredator of the fruit trees. "It is a most impudent thief; it destroys more than it eats by its random, hasty way of plucking and breaking the fruits, and when about to return to the forest, carries away all it can in its hands or under its arms."

Characters.—Crown with hairs elongated into a conical central crest. Fur bright red; crown bright red like the back, with a black spot.

Distribution.—Brazil.

Characters.—Hair of crown long and erect, forming a central conical crest. Fur brown, reddish-washed, especially on the thighs, the hairs with several pale rings; a streak on the sides of the neck bent down on the front of the shoulders, yellow; belly reddish; crown, temples, whiskers, outer and inner side of the limbs and tail, black; hair of face deep black; crown-spot broad, with a broad line to the forehead and another, on each side, to the whiskers.

Distribution.—Brazil.

Characters.—Head large in proportion to the body. Hair of crown short, reflexed, without crest or "horns." Tail with rather long hair. Face, forehead, throat, shoulders, and crest white. General colour of body light or reddish-brown; back and outer side of the limbs, brownish-red.

Distribution.—Generally distributed through the forests of the level country of the Upper Amazon.

Habits.—The Caiarara, as the Tupi Indians name this species, lives in troops in the forests and feeds on fruits. Mr. Bates, who kept one in captivity for a considerable period during his stay in the Upper Amazon region, describes it as "a most restless creature, but not playful like most of the American Monkeys; the restlessness of its disposition seeming to arise from great nervous irritability and discontent. The anxious, painful, and changeable expression of its countenance, and the want of purpose in its movements, betray this. Its actions are like those of a wayward child; it does not seem happy even when it has plenty of its favourite food, bananas; but will leave its own meal to snatch the morsels out of the hands of its companions. It differs in these mental traits from its nearest kindred, for another common Cebus, found in the same parts of the forest, the Prego Monkey (C. cirrifer), is a much quieter and better tempered animal.... The Caiarara [called Ouavapavi, by Humboldt] is always making some noise or other, often screwing up its mouth and uttering a succession of loud notes resembling a whistle." It is the most wonderful leaper of the whole tribe. Mr. Bates has also recorded:—"The troops consist of thirty or more individuals which travel in single file. When the foremost of the flock reaches the outermost branch of an unusually lofty tree he springs forth into the air without a moment's hesitation and alights on the dome of yielding foliage belonging to the neighbouring tree, maybe fifty feet beneath; all the rest following the example. They grasp, on falling, with hands and tail, right themselves in a moment, and then away they go along branch and bough to the next tree." Mr. Belt also mentions having kept a White-fronted Capuchin in captivity for a long time. Its actions, he tells us, were very human-like. "He had quite an extensive vocabulary of sounds, varying from a gruff bark to a shrill whistle; and we could tell by them, without seeing him, when it was he was hungry, eating, frightened, or menacing; doubtless one of his own species would have understood various minor shades of intonation and expression that we, not entering into his feelings and wants, passed over as unintelligible."

Characters.—Hairs of crown short, reflexed, but not elevated into a crest. Fur brown, washed with yellow; crown-spot dark brown, narrow, prolonged down the nose, and expanded backward on to the nape of the neck; sides of face, throat, chest, and front part of shoulders, greyish-yellow.

Distribution.—Widely distributed in the great forests from Paraguay to the United States of Colombia.

Habits.—This Capuchin wanders about among the high forest trees in small companies of from ten to a dozen, the larger number being females. It is very timid, and keeps well out of sight, so that it is difficult to watch its habits. Rengger, in his "Säugethiere von Paraguay," had more than once an excellent opportunity of observing these interesting Monkeys, and has given a capital account of them. He specially mentions the great affection the mother has for her offspring. "The mother's love," he says, "shows itself by the great care with which every old one handles her young, by laying them on the breast, by watching them, by searching their fur, and by the attacks they make on any intruder." In January the female gives birth to a single young one, and keeps it at her breast for the first week; later on she carries it partly on her back, partly under her arm. When sleeping the Weeping Çai curls itself up, covering its face with its arms and tail.

The leader of a troop shares his feelings with the others by various motions, and by giving utterance to certain noises, which are taken up by the others. Their feelings are also exhibited by a kind of laughing and crying. Rengger kept some of these Monkeys for several years in captivity in their own country, and says that, when happy, they uttered a peculiar tittering sound; they express agreeable sensations by drawing back the corners of the mouth without uttering any sound; this he supposed to be laughing, but, as Mr. Darwin remarks, it would be more appropriately called a smile. When crying, their eyes fill with tears, but never flow down the cheeks. When in pain or terror, the form of the mouth, as observed by Mr. Darwin at the Zoological Gardens in London, is quite different from that expressing pleasure or satisfaction; and high shrieks are uttered.

Specimens of this species have been kept in captivity in Europe for six and seven years.

Characters.—Hairs of crown short; those on the side of the dark and narrow crown-spot, produced on the sides into two horns or crests. Fur thick and long, mingled with still longer glancing hairs; general colour blackish-brown; top of head, nape of neck, and whiskers black. (Gray.)

Distribution.—Brazil.

The following species has been described by Dr. Gray, but very little, if anything, is known of its habits or of the exact locality in which it lives.

Characters.—Fur nearly uniform pale yellowish-fulvous; the cheeks, whiskers, and hair under the throat, greyish; the crown, nape, and middle part of the back rather darker; outside of the leg somewhat redder; hair on top of head and nape rather elongate, directed backward, but not forming a crest.

Distribution.—Brazil.

Characters.—Fur soft; hairs of crown of head radiating from a centre, directed forward in front, forming a transverse crest on the middle of the crown. Face, throat, chest, and front of shoulders, pale greyish-brown; back of head and eyebrows blackish. General colour of body pale sooty-brown, washed with golden; outer side of limbs golden-buff.

Distribution.—United States of Colombia.

Characters.—Hair of crown elongate, divided by a central line diverging to the eyebrows, forming an erect transverse crest behind them. Fur blackish-brown; sides of face pale ashy; front of shoulders and of arms and outer side of legs, yellowish. Digits long and very slender.

Distribution.—Brazil.

BONNETED CAPUCHIN. (Plate XXI in 2nd. edition, 1896)

Characters.—Hairs of head elongate, diverging in all directions; fur long, brown, slightly washed with yellow, more markedly on the thighs; sides of forehead paler; sides of neck, outer sides of shoulders and arms, fulvous; crown and nape of neck, blackish.

Distribution.—Brazil.

Characters.—Top of head black, with a band of the same colour passing in front of the ears, and terminating on the lower jaw; forehead, temples, and face, white; ear-tufts white; chin, throat, and upper side of feet white; upper side of tail, anterior part of the fore-feet and ankles, dusky; rest of body brown, lighter on the sides, becoming yellowish on the rump, the lower part of the body, and the under side of the tail. Length of the body, 17 inches; of the tail, 19 inches.

Female.—Paler in colour above than the male; the dark colour of the tail and of the limbs more extended.

Distribution.—Paraguay.

Habits.—This rare Capuchin lives, as Azara relates, in the forests of Paraguay, and is met with both in single couples and in small troops. They are very lively little animals, ever in motion, swinging themselves from tree to tree by means of their tails, the mothers of the company generally carrying their single young one on their back. When once tamed they become very affectionate; when angry they can give vent to excruciating screams. Their ordinary voice resembles that of someone laughing with all their might, and crying Hu! hu! hu!

Only once has a specimen of this Capuchin been an inmate of the Zoological Gardens in London.

Characters.—In colour closely resembling C. fatuellus, but the hair is longer all over, silky, and of a dusky hue, especially on the hinder part of the body. The lumbar vertebræ are four in number, and there are also fourteen pairs of ribs.

Distribution.—Unknown.

The animals grouped under the genus Lagothrix are readily distinguished by having a heavy body, and a rounded head, with the muzzle much flattened, and the nostrils nearly circular, but not approximated. More conspicuous than any other external character is the woolliness of their under-fur.

The name Lagothrix was given by Humboldt to the first specimen he found, because of the similarity of its fur to that of the hare, and hence this name, from, a hare, and , hair, was adopted for the new genus, which was afterwards established by Geoffroy St. Hilaire.

The hair of the crown is short and directed backwards; the tail is long and perfectly prehensile, being naked and sensitive for a considerable distance back from the tip. The limbs are moderately long, and the thumb and great-toe are well developed, the nails of the digits being compressed and pointed.

In regard to the skeleton, the skull of Lagothrix, as Dr. Slack points out, can be readily distinguished from that of the Capuchins by a broad, well-marked, articulation taking place between the pre-maxillary and the nasal bones at right angles to the suture between the latter, while in the Capuchins no true articulation takes place between these bones. The lower jaw is larger than in Cebus, approaching the size and form of Mycetes. The incisor teeth are small and unequal, the upper inner incisor being the largest; the canines are very large and grooved in front.

The Woolly Monkeys are slow in motion, gregarious, diurnal, and arboreal. The "Barrigudos," as they are called by the Portuguese colonists, live exclusively on fruits, and are larger and less active than the Capuchins. They are confined to the forests of the Ecuador district of the Upper Amazon Valley, and along the slopes of the Andes, north to Venezuela and south to Bolivia.

They are of a mild disposition, and, as Mr. Wallace remarks, they are the species "most frequently seen in confinement, and are great favourites, from their grave countenances, which resemble the human face more than those of any other Monkeys, their quiet manners, and the great affection and docility they exhibit."

Characters.—Body large and heavy; face naked, black, and wrinkled; forehead low, the eyes projecting; a few scattered white hairs on lips. Hair of under surface hoary, and longer than that of the upper surface.

Adult Male.—General colour blackish, hoary-grey, the hairs being dark grey, tipped with black. Head, chest, hands, under surface of body, and tip of tail, black. Length of the body, from 19 or 20 inches to 27 inches in very large specimens; tail from 24 to 26 inches.

Young.—Hoary grey, darker on the belly and inner surface of the limbs; hands and top of head black.

HUMBOLDT'S WOOLLY MONKEY.

Distribution.—This Monkey was discovered by Humboldt on the Guaviaré, a branch of the Orinoco river. It occurs in the Upper Magdalena Valley, Colombia, where it is known as the "Churuco" river. Its true habitat is the district south-west of the Rio Negro towards the Andes. It is unknown in the Lower Amazon Region.

Habits.—The "Caparro," as the Orinoco Indians named this species to Humboldt, or "Macaco barrigudo," as the Portuguese settlers call it, is entirely an arboreal animal, living exclusively on fruits, on which it is a most voracious feeder. The name of "big-bellied," which barrigudo means, is probably obtained from the effects of this habit. Its manners in captivity are grave, and its temper, according to Mr. Bates, is mild and confiding, like that of the Coaitas, or Spider-Monkeys. Owing to these traits, the Barrigudo is much sought after as a pet; but it is not hardy like the Coaitas, and seldom survives a passage down the river to Pará. Nevertheless, the Zoological Society has had a considerable number of these Monkeys in confinement during the past twenty years. Mr. Bates also states that it is much persecuted by the natives on account of the excellence of its flesh as food. "From information given me," he says, "by a collector of birds and mammals whom I employed, and who resided a long time among the Tacuna Indians, near Tabatinga, I calculated that one horde of this tribe, 200 in number, destroyed 1,200 of these Monkeys annually for food. The species is very numerous in the forests of the higher lands, but, owing to long persecution, it is now seldom seen in the neighbourhood of the larger villages."

Characters.—Large in size; face naked, black; general colour dark reddish-grey, the hairs being reddish-brown at the base, and tipped with grey or black; head, face and hind hands darker brown; chest, upper side of fore-arms, and under surface of body dark brown, or almost black; sides of body, base of the tail and perineal region brownish-red; hair of chest and under surface long and rather rigid.

Distribution.—The Brown Lagothrix, also called "Capparo" by Humboldt, is common in the forests of the low country over the whole of the Valley of the Peruvian Amazons. It has been recorded from the Valley of the Copataza river, and also from Macas, both in Cis-Andean Ecuador.

Habits.—These Monkeys go about in pairs, in troops of about twelve to fourteen, and frequent the great forest trees. They are often found in company with species of other genera, such as the Howlers. They are exclusively fruit-eaters, and are in great request as food; large numbers, consequently, are destroyed annually for this purpose.

The members of this genus resemble in general form the Spider-Monkeys, to be presently described, and they present also many resemblances to the foregoing species of the Woolly Monkeys. Their limbs are long and slender, and their body heavy, and covered with a woolly under-fur. Their head is rounder than in the Capuchins. The face is flat, and the facial angle large. The nose has the partition between the nostrils narrower than in the other species of the family, and the nostrils are themselves more approximated, circular in form, and directed more downward than outward, thus showing some approach to the position of the nostrils in the Old World Apes. Their fore-limbs are long and slender, and the thumb is often entirely absent (as in the Guerezas of Africa), or there may be a very rudimentary digit, which sometimes ends in a small nail. The nails of the digits are, as in Lagothrix, very compressed and sharp. The tail is longer than the body, naked on the under side, and sensitive at its termination, and therefore prehensile.

The skull is globular, and the pre-maxillary bones articulate with the nasal bones by a broad surface. The incisor teeth are equal in size; the canines are small, and of the same length as the incisors, and the molars, which are vertically higher than the canines, are thick and quadrangular. The lower jaw is dilated behind, somewhat less than in Lagothrix.

The Woolly Spider-Monkeys are very rare, and little is known of their habits. They are confined to the south-eastern coast forests of Brazil, that region to the south of Cape San Roque, whence, as far as Rio Grande do Sul, ever-verdant forests, as Mr. Wallace has described, clothe all the valleys and hills of the lowland region, stretching as far west as the higher mountain ranges parallel to the coast, and even up the valleys of the larger rivers a long way into the interior of the country.

Characters.—Male.—Size small; face nude, flesh-coloured; general colour of body yellowish-brown, darker on the back of the head, with a few long black hairs on the forehead; hairs of head short and directed backward; buttocks, vent, base of tail and perineal region dark ferruginous-brown; the thumb wanting or rudimentary. Length of body, 22 inches; tail, 26 inches.

Female.—Ashy-brown, instead of yellowish-brown, in appearance.

Young.—In some young specimens the general colour is dark brown, with the sides of the face white.

Dr. Slack observes, in the "Proceedings of the Academy of Natural Sciences of Philadelphia" for 1862, in reference to this species: "I had long suspected that the three species of this genus described by Isidore Geoffroy St. Hilaire, were in reality one and the same; no specific characters are manifest in their coloration, or skulls, the supposed differences being based upon the development of the anterior thumbs, this member being absent in B. arachnoides, replaced by a small nailless tubercle in B. tuberifer, and surmounted by a nail in B. hemidactylus. In the "Magazin" of Messrs. Verreaux, in Paris, I found specimens having upon one hand the tubercle, and upon the other the nailed thumb, others with the tubercle on one hand, but absent upon the other. St. Hilaire himself, in his "Catalogue of the Primates," expresses a doubt as to whether B. arachnoides and B. hemidactylus are really distinct. In September and October, 1860, I was unable to find B. hemidactylus in the Paris Museum, all the Brachyteles being labelled Eriodes arachnoides."

Distribution.—Confined to the wooded region of the south-east of Brazil.

Habits.—Arboreal, diurnal, and (it is supposed) gregarious, frequenting the high forest trees, and subsisting on fruits.

This is the fourth remaining genus of the Cebinæ, the last Sub-family of the Cebidæ. With the description of the Spider-Monkeys, therefore, we shall have passed in review all the species of the New World Platyrrhine section of the Anthropoidea. The species of this group derive their trivial name from their long and slender limbs; the name applied to them, however, in their native forests by the Indians of Brazil is "Coaita." They are characterised by their light and slender body, which is narrower across the loins than across the chest. The head is rounded, the forehead salient, and the muzzle somewhat projecting. Both pairs of limbs are much elongated, the hind-limbs being shorter, however, than the fore-, and the thumb of the fore-limb is sometimes very rudimentary, being only a nailless tubercle—or, in the majority of the species, entirely absent, rendering the hand a much less perfect organ for holding or picking up small objects, such as fruits, &c.; but its absence probably does not affect, if it does not even benefit, the hand as an organ for climbing and catching hold again after a long leap. The nails and other digits of both limbs are compressed, but much less so than in Brachyteles and Lagothrix. The tail is very long, generally exceeding the length of the body and head, and is nude on the under side, and very sensitive towards its termination. As a prehensile organ it has reached the summit of strength and perfection. "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." (Mivart.) The body is covered with long, rather coarse, generally black, hair, and has no woolly under-fur, as in Lagothrix and Brachyteles.

With regard to the skeleton of Ateles, the lumbar region of the vertebral column is short, and the dorsal segment attains a greater relative length than in any other Ape, being over nine-twentieths of the total length of the spine, without the tail. (Mivart.) The dorsal and lumbar vertebræ together number eighteen. In the tail there are twenty-three vertebræ, flattened on the under side, and exceptionally provided with bony processes, serving as points for the attachment of muscles for rendering it as efficient a prehensile organ as possible. The length of the whole arm and hand in Ateles, in proportion to that of the spine, is 174 to 100; but without the hand it is shorter than the spine, the hand itself being only slightly shorter than the latter. The proportion of the hind-limb to the spine is somewhat less, being 169 to 100. The thumb is reduced to a single metacarpal bone, to which, usually, a single minute nodular phalanx [finger-bone] is articulated, and is completely hidden beneath the integument. Although thus rudimentary and functionless, all its characteristic muscles, except one (the long-flexor) are present. (Huxley.) The upper incisors are unequal, the interior being the larger. There is a space (diastema) between the incisor and the canine teeth (as in all Anthropoidea, except Man); the canines are large and conical; the upper molars large, and their crowns four-cusped, with transverse ridges between the outer and inner front cusps and the outer and inner hind cusps, and also an oblique ridge crossing from the outer front cusp to the inner hind one. In the larynx of Ateles there is a single median air-sac opening from the back of the windpipe, but there is no such extension of the resonating apparatus as is seen in the Howlers (Alouatta). In its brain Ateles exhibits in some respects a higher type than in even the Old World Apes.

In regard to this group of Monkeys, the late Mr. H. W. Bates made the following interesting observations:—"In the Coaitas the tail reaches its highest perfection as a prehensile organ; and on this account it would perhaps be correct to consider the Coaitas as the extreme development of the American type of Apes. As far as we know from living and fossil species, the New World has progressed no further than the Coaita towards the production of a higher form of the Quadrumanous order. The tendency of Nature here has been, to all appearance, simply to perfect these organs, which adapt the species more and more completely to a purely arboreal life; and no nearer approach has been made towards the more advanced forms of Anthropoid Apes, which are the products of the Old World solely. The tail of the Coaita is endowed with a wonderful degree of flexibility. It is always in motion, coiling and uncoiling like the trunk of an Elephant, and grasping whatever comes within reach.... The flesh of the Coaitas is much esteemed by the natives in this part of the country [Obydos, on the Amazon].... One day I went on a Coaita hunt. When in the deepest part of a ravine we heard a rustling sound in the trees overhead, and Manoel [the guide] pointed out a Coaita to me. There was something human-like in its appearance [which is very characteristic of them], as the lean, dark, shaggy creature moved deliberately amongst the branches at a great height. I fired, but unfortunately only wounded it in the belly. It fell with a crash headlong about twenty or thirty feet, and then caught a bough with its tail, which grasped it instantaneously, and then the animal remained suspended in mid-air. Before I could re-load it recovered itself, and mounted nimbly to the topmost branches out of the reach of a fowling-piece, where we could perceive the poor thing, apparently probing the wound with its fingers. Coaitas are more frequently kept in a tame state than any other kind of Monkey. The Indians are very fond of them as pets, and the women often suckle them when young at their breasts. They become attached to their masters, and will sometimes follow them on the ground to considerable distances.... The disposition of the Coaita is mild in the extreme; it has none of the painful, restless vivacity of its kindred, the Cebi, and no trace of the surly, untameable temper of its still nearer relatives, the Mycetes, or Howling-Monkeys. It is, however, an arrant thief, and shows considerable cunning in pilfering small articles of clothing, which it conceals in its sleeping place."

THE VARIEGATED SPIDER-MONKEY.

The Coaitas are like the rest of the Cebidæ, essentially quadrupedal, but they occasionally assume the erect posture. They are purely arboreal in habit, living in small companies in the very high trees of the forest.

Their geographical distribution is very wide. They extend over the whole area of the Cebidæ, i.e., over two of the sub-regions, the Brazilian and Mexican, of the Neotropical Region.

Characters.—Male.—Fur of body abundant, long, and soft; hair of back and top of head long and directed forwards, and projecting over the forehead; beneath and behind the cheeks a band of longish hairs, directed forwards. Top of head, back, front aspect of the entire arms, and of the legs to the knees, hands, feet, and upper side of tail glossy blue-black; a band across the forehead rufous-yellow; the hairs directed upwardly, bordered by a narrower streak of deep black over the eyes; the under side of the fore-limbs, the posterior aspect of the thighs, and the entire leg, the buttocks, and the whole of the under side of the tail as far as the nude portion (which is black), rich orange-yellow; under surface of body paler. Face naked, black, and bordered by a broad white patch of whiskers, reaching from the temple nearly to the angle of the mouth. The black part of the limbs and legs near to the yellow colour, varied with more or fewer yellow hairs.

Female and Young Male.—Similar to the adult male, but less in size, and the coloration paler than in the adult male. Elbows and feet black; under side of the body greyish-yellow. The white stripe on the sides of the face is wanting in the young female.

Distribution.—Chyavetas, Nauta, and Elvira in the Peruvian Amazons; Upper Rio Negro, Serra de Cocoi; Upper Cauca river, a southern confluent of the Orinoco; Venezuela. "This species is found on both sides of the Peruvian Amazon (or Marañon), on both shores of the Huallaga, and in the interior forest near the town of Chamicuros. I was told by some of the oldest Indians that these animals are common in the dense forest on the hills near the latter town, their range extending between the Huallaga river and Ucayali river to the head-waters of the Huallaga, between the towns of Lamas and Sarayaçu.... Then again on the Rio Tigri ... and over the head-waters of the Rio Napo, Rio Japurâ and Rio Negro, where Natterer first discovered it." (Bartlett.)

Habits.—This Monkey, the "Chuva de Baracamorros" of Humboldt, which is the most beautifully coloured of its group, is said to go about in small parties, passing through the forest at a rapid rate, feeding on different kinds of berries.

Characters.—Body light greyish-drab all over; hands, elbows, feet, knees, and the upper side of the extremity of the tail, black; face black, with the exception of the lips and a ring round the eyes, broad above and narrow below, flesh-coloured. Hair of forehead reflexed, meeting that of the crown above the eyes, forming a triangular patch of erect black hairs. Top of the head and upper part of the tail buff. Length of body, 17 inches; of tail, 21 inches. Thumb entirely wanting.

This species is remarkably variable. The description given above belongs to the form described as A. melanochir by Desmarest from the same specimen in Paris, which Kuhl described under the name of A. geoffroyi. Every gradation is to be met with between this and the form described by Dr. Gray as A. ornatus, in which the face is entirely black, the whiskers pale reddish-yellow, the patch of erect black hair on the forehead yellowish at its base; the top of the head, sides, lower back, rump, upper part of the arms, outer, inner and posterior portion of the thighs and legs, and under side of the base of the tail, brownish-red; nape, shoulders and remainder of the tail reddish-brown, washed with black; lower part of arms, fore-arms, hands, feet, and anterior aspect of thighs and legs, black.

In some specimens the grey, or reddish-black colour, merges on the under surface, into yellowish-cream, or rufous, and the black wash is more or less distributed.

Mr. Alston, in speaking of this species, remarks that the best character by which the darker (A. ornatus) forms may be distinguished from our next species (A. rufiventris) is the want of a distinct line of demarcation between the colours of the upper and lower parts, the tint of the flanks, whatever it may be, passing almost insensibly into that of the breast and belly in all the varieties.

Distribution.—The variation in colour described above is not due to local causes, every variety occurring between the lightest and darkest, in all the regions which this species is known to inhabit. The localities from which it has been recorded are on both the Atlantic and Pacific coasts of Nicaragua; Costa Rica, where it occurs in large numbers from the coast forests up to nearly 7,000 feet on the mountains; Panama, and the U.S. of Colombia.

Habits.—Geoffroy's Spider-Monkey is gregarious and arboreal, frequenting the highest trees of the forest, both in the low country and at high elevations, and living on fruits and insects, but chiefly on the former. Mr. Belt relates that on the banks of the Antigua he saw a valuable tree, the "Nispera" (Achras sapota), growing on the dryer ridges. "It bears a round fruit about the size of an apple, hard and heavy when green, and at this time it is much frequented by the large yellowish-brown Spider-Monkey (Ateles), which roams over the tops of the trees in bands of from ten to twenty. Sometimes they lay quite quiet until I was passing underneath, when, shaking a branch of the Nispera tree, they would send down a shower of the hard round fruit; but fortunately I was never struck by them. As soon as I looked up they would commence yelping and barking and putting on the most threatening gestures, breaking off pieces of branches and letting them fall, and shaking off more fruit, but never throwing anything, simply letting it fall. Often when on lower trees, they would hang from the branches, two or three together, holding on to each other and to the branch with their fore-feet and long tail, whilst their hind-feet hung down, all the time making threatening gestures and cries. Sometimes a female would be seen carrying a young one on its back, to which it clung with legs and tail, the mother making its way along the branches, and leaping from tree to tree, apparently but little encumbered by its baby. A large black and white Eagle is said to prey upon them, but I never saw one, although I was constantly falling in with troops of the Monkeys. Don Francisco Velasquez, one of our officers, told me that one day he heard a Monkey crying out in the forest for more than two hours, and at last, going to see what was the matter, he saw a Monkey on a branch and an Eagle beside it trying to frighten it to turn its back, when it would have seized it. The Monkey, however, kept its face to its foe.... Velasquez fired at the Eagle, and frightened it away. I think it likely, from what I have seen of the habits of this Monkey, that they defend themselves from the Eagle's attack by keeping two or three together, thus assisting each other, and that it is only when the bird finds one separated from its companions that it dares to attack it."

Mr. Osbert Salvin met with several of these Monkeys near the town of San Juan del Sur, in Nicaragua. He was walking up the course of a half-dry stream when he came upon a troop of Monkeys which had come to a pool to drink, and were climbing about the low trees on the bank of the watercourse. Most of the troop consisted of Cebus hypoleucus, but with them were several Ateles of the present species, of one of which Mr. Salvin wrote a description as it sat jabbering at him and throwing down sticks from a branch above his head. Mr. Salvin also told Mr. Alston that it was not unusual to see Monkeys kept in confinement in the court-yards of the Spanish houses in Guatemala. Amongst them were occasionally to be seen specimens of Geoffroy's Spider-Monkey; but he always found that they had been brought from Nicaragua or Costa Rica, the species not extending into Guatemala.

Characters.—Fur rough, upstanding less on the tail than on the body, that on the forehead erect and directed backwards, that on the top of the head long, projecting forward. Face and muzzle, except a black line from the side of the nose and inner corners of the eyes to the cheeks, flesh-coloured. General colour uniform black, but the whole under surface deep bright rufous, this colour extending but slightly on to the inner surface of the limbs. Thumbs entirely wanting.

Differs from A. geoffroyi by its flesh-coloured face and by the two colours of the upper and under sides being clearly defined. Length of body, 12 inches; of tail, 15½ inches.

Distribution.—This species was first discovered on the Atrato river, in Northern Colombia, and has since been found in Panama.

Habits.—The Red-bellied Spider-Monkey is very rare, only one or two specimens having yet been obtained. Nothing is, therefore, known of its habits.

Characters.—Very similar to A. ater in its coarse and entirely black fur, but differing in the naked and flesh-coloured face. Hairs of forehead long and projecting anteriorly; tail one-quarter longer than the body; hands generally entirely lacking the thumbs, though sometimes a rudimentary thumb is present, and that occasionally on one hand only. Naked portion of tail covered with sensory papillæ, rendering it more sensitive, so it is said, than the hand. Length of body, 24 inches; tail, 30 inches. The skull in some specimens of the thumbed variety is compressed laterally, and shows a sagittal crest along the top.

Distribution.—This species is spread over Guiana, the forests of the Ucayali and Huallaga rivers in eastern Peru, and the northern part of Brazil, where it is known as the "Coaita," taking the place of the more northern Ateles ater. "It occurs," says Mr. Bates, "throughout the lowlands of the Lower and Upper Amazons, but does not range to the south beyond the limits of the river plains." In the higher part of the Rio Negro it comes down to the north bank, but does not cross to the south bank of the river.

Habits.—This species is the best known of all the Spider-Monkeys. It is captured in large numbers, when young, by the natives of Guiana, and as they bear captivity well, many of them have been brought to Europe. They live in larger troops than do some of the other members of its genus; indeed, these companies are said to number as many as a hundred. They are very easily tamed, and become very affectionate. They live chiefly on fruits, principally on a species of palm-nut. Dampier, however, says, apparently of this species of Ateles: "The Monkeys come down by the Sea-side [at low water] and catch them [the Periwinckles and Muscles]; digging them out of their Shells with their Claws." Large numbers of this species are also annually killed for food, their flesh being held in high esteem by the natives.

Characters.—Similar in size and coloration to A. paniscus. Body lean; hair moderately long and coarse. Face naked, black, except the skin round the eyes, which is flesh-coloured; general colour black; under surface of body and inner sides of limbs, ashy-grey. It differs from A. paniscus by having the forehead, crown of head, a spot on each side of the nose, and the whiskers, white.

A specimen in the British Museum has four pre-molars in each upper jaw, instead of the normal three of the Cebidæ.

Distribution.—This species was discovered by Humboldt on the banks of the Santiago river. Mr. Bates says "it is never met with in the alluvial plains of the Amazons," nor, he believes, on the northern side of the great river-valley, except towards its head-waters near the Andes.

Habits.—According to Von Humboldt, this Spider-Monkey—known as the "White-Whiskered Coaita"—is very fierce and libidinous. Mr. Bates encountered this large and handsome species on the Cupari river, a tributary of the Tapajos, one of the large southern affluents of the Amazon. Here he could get scarcely anything but fish to eat, and, as this diet did not agree with him, he was obliged to have recourse to the Coaita flesh. "I thought," he says, "the meat the best flavoured I have ever tasted. It resembled beef, but had a richer and sweeter taste.... We smoke-dried the joints instead of salting them; placing them for several hours on a framework of sticks arranged over a fire. Nothing but the hardest necessity could have driven me so near to cannibalism as this, but we had the greatest difficulty in obtaining here a sufficient supply of animal food." Von Humboldt has also referred to the cooking of these Monkeys by the natives of the Upper Orinoko. "The manner of roasting these anthropomorphous animals," he writes, "contributes singularly to render their appearance disagreeable in the eyes of civilised Man. A little grating or lattice of very hard wood is formed, and raised one foot from the ground. The Monkey is skinned and bent into a sitting posture; the head generally resting on the arms, which are meagre and long; but sometimes these are crossed behind the back. When it is tied on the grating a very clear fire is kindled below.... On seeing the natives devour an arm or leg of a roasted Monkey, it is difficult not to believe that this habit of eating animals which so much resemble Man in their physical organisation, has in a certain degree contributed to diminish the horror of anthropophagy among savages. Roasted Monkeys, particularly those that have a very round head, display a hideous resemblance to a child; the Europeans, therefore, who are obliged to feed on Quadrumanes, prefer separating the head and the hands, and serve up only the rest of the animal at their tables. The flesh of Monkeys is so lean and dry that Mr. Bonpland has preserved in his collections at Paris an arm and hand, which had been boiled over the fire at Esmeraldas; and no smell arises from them after a great number of years."

Characters.—Entirely black; fur silky, and longer on the head and tail than on the body; fur on top of head directed from behind forwards, falling over the forehead, meeting the backwardly directed hairs of the forehead and forming a tuft. Face black, the upper part naked; chin with stiff black hairs mixed with a few white ones. Ears oval and human-like in form, the upper part movable at will. Thumbs entirely wanting. Length of body, 19 inches; tail, 26 inches.

Distinguished from A. paniscus, which it closely resembles, by the black colour of its face, and the direction of the hairs on the forehead.

Young.—Lighter in colour than the adults; sometimes brown on the back and the outer side of the limbs.

Distribution.—The Black-Faced Spider-Monkey ranges from Panama, through the United States of Colombia to Eastern Peru.

Habits.—Entirely arboreal, living in large troops, and feeding on fruits.

Characters.—Hair of forehead elongate. Fur in general moderately long, black, with greyish-white hairs intermingled, giving it a grizzled appearance; under side of tail grey. Similar to A. ater and A. paniscus, but distinguished by the intermixture of grey hairs, and by the colour of the under side of the tail. Thumbs absent.

Young Male.—Rather lighter in colour, especially on the under side of body; tail black above, grey beneath. Length of body, 14 inches; tail, 16 inches.

Distribution.—The habitat of this species is not certainly known. Dr. Sclater considers it probable that it will turn up in some part of the Central American or the Colombian coast.

Characters.—Fur thick. Hairs long, shining, crisp, deep black above, the hairs of the back with brownish tips; the under side of the body and inside of the limbs black; crown of head deep coffee-brown. Length of body about 20 inches; of the tail, 26 inches, according to the dimensions taken from the skin of a young animal by Dr. Sclater. Thumbs entirely wanting.

Distribution.—In 1860, when Mr. L. Fraser returned from Ecuador, he spoke of a large Monkey he had seen, but had not obtained, in the valleys of Western Ecuador. It remained unknown until it was shot, and brought to England by Mr. Buckley some ten years later. It was the only Monkey, he says, except a Mycetes, which he saw in Trans-Andean Ecuador.

Habits.—These, doubtless, do not differ from those of other Spider-Monkeys.

Characters.—Hairs of body long, but thin on the head, body, limbs and tail; hair of crown very long and projecting over the face and the sides of head, forming what has been called a "hood." Face nude, flesh-coloured; cheeks and lower jaw nearly nude also, but the skin of a blackish hue. Hair on back black, intermingled with numerous others which are yellowish-grey in colour; crown and back of head, hands, and feet black—the hairs black throughout. Nude part of tail flesh-coloured. The hands have a rudiment of a thumb in the shape of a small tubercle. Length of body, 14½ inches; of tail, 27½ inches.

Distribution.—The Hooded Spider-Monkey is very rare, and very different from any other member of its group in regard to the hair of its head. Its native country is still a matter of uncertainty. Dr. Sclater, however, remarks in the "Proceedings of the Zoological Society" for 1881: "I have some reason to suppose it may be from the northern coast of Colombia, as I am told that a black Spider-Monkey, with long hair over its head, is occasionally brought for sale into Cartagena."

Characters.—Closely allied to Ateles geoffroyi. Hair abundant, long, soft, and flaccid. Face flesh-coloured, except for a black bar from the corner of the eye to the cheek; forehead black, its hair short, reflexed, and uniting, so as to form an erect, crest-like ridge, with the fur on the top of the head, which is directed forward. General colour above black to reddish-brown; the head, back, outer side of the entire fore-limb and of the lower part of the hind-limb, hands, and feet, and upper surface of tail deep black; sides of body, loins, and thighs yellowish-brown or dull black washed with rufous; whiskers, throat, whole of under surface of body, inside of fore- and hind-limbs, and under surface of tail (this sometimes black) yellowish-cream colour, but very variable, sharply defined from the dark colour of the upper parts. Thumb entirely wanting. Eyes dark yellowish-grey. May be distinguished from the dark form of Geoffroy's Spider-Monkey by the sharp definition of the colours of the upper and under sides of the body.

Distribution.—This species, also spoken of as the Mexican Spider-Monkey, is known to occur right across Guatemala; it is by no means uncommon, Mr. Salvin says, in the forest country on the northern part of Vera Paz, and he also saw a troop at the summit of the ridge of mountains which connects the Volcan de Fuego with the main Cordillera, at about 8,000 feet above the sea.

The late Prof. Liebmann, the Danish botanist, obtained a specimen, according to Prof. Reinhardt, "in the neighbourhood of the small place Mirador, situated not far from the volcano of Orizaba, in the State of Vera Cruz.... He met with it also in the eastern parts of the State of Oaxaca.... But at the same time he expressly states that he never met with this Ateles, nor, indeed, with any other Monkey, on the Pacific slope of the Great Cordillera in Oaxaca, and that, as far as he could learn, Monkeys are to be found on the western coast only south of Tehuantepec." This species is the only Spider-Monkey certainly known to range as far north as Mexico. According to M. Sallé, the most northern locality for Monkeys with which he was acquainted, was in the State of San-Louis Potosi, about 23° N. latitude, on the upper part of the basin of the Tampico river. (Alston.)

Habits.—The Mexican Spider-Monkey is, like the foregoing members of the genus, arboreal, consorting together in small troops, and feeding on fruits. Prof. Liebmann observed it in small troops in the deep barrancas, up to an elevation of 2,000 feet above the sea, on the Orizaba volcano, and in the forests of Oaxaca, to 4,000 feet. Mr. Salvin, on the volcano of Atitlan, in Guatemala, at a height of between 5,000 and 6,000 feet, met several troops of this species on the tops of the higher trees of the forest. These parties of Monkeys were usually about twenty in number and of all ages. On approaching them they did not evince any alarm, but kept uttering a constant querulous sort of bark, and moved from time to time so as to get a better view of the intruder. A few days afterwards, during an excursion to the same volcano, when the summit, 11,800 feet above the sea, was reached, numerous troops of Ateles were seen in the forest, from an elevation of 7,000 feet to as low as 2,500 feet on the outskirts of the coffee plantations of San Agustin.

Now that we have passed in review the whole of the Anthropoid species inhabiting the New World, a short account of the regions to which they are confined will be of some interest. The most northern limit of Monkeys is, as mentioned above, the State of San-Louis Potosi, about the latitude of 23° North. Their most southern limit attains to nearly 25° of South latitude. They are now confined to the Mexican and Brazilian sub-regions of what has been defined as the Neotropical Region, by Dr. A. R. Wallace, in his great work, "The Geographical Distribution of Animals." The Mexican sub-region belongs to the Neotropical Region, one of those six great areas into which the globe has been divided off by Dr. Sclater on the basis of the geographical distribution of the animals that now inhabit it—the final product of the slowly-changing features of the earth's surface, and of the form, structure, and habits of its animal and vegetable life.

The Mexican sub-region forms the northern part of the Region, and, to condense Mr. Wallace's account of it, it is of comparatively small extent; but the whole of its area is mountainous, being, in fact, a continuation of the great range of the Rocky Mountains. It varies in elevation above the sea from 6,000 to 18,000 feet. "With the exception of the elevated plateaus of Mexico and Guatemala, and the extremity of the peninsula of Yucatan, the whole of Central America is clothed with forests; and as its surface is much broken up into hill and valley, and the volcanic soil of a large portion of it is very fertile, it is altogether well adapted to support a varied fauna, as it does a most luxuriant vegetation." In this region only species of Spider-Monkeys (Ateles), of Howlers (Alouatta), of Capuchins (Cebus), of Night-Monkeys (Nyctipithecus), and of Squirrel-Monkeys (Chrysothrix) are found. The Spider-Monkeys and the Howlers alone extend so far North as Mexico, and the Night-Monkeys reach to Nicaragua, while the Squirrel-Monkeys and Capuchins have penetrated no further than to Costa Rica.

The Brazilian Sub-region includes all the open plains and pasture lands, surrounded by, or intimately associated with, the forests. Its central mass consists of the great forest plain of the Amazons, from the north-east coast of Brazil to high up in the Andes on the west, a stretch of more than 2,000 miles; and from the mouth of the Orinoko to near La Paz in the Bolivian Andes, a distance of 1,900 miles, of continuous forest in both directions. Within this area are some open "campos" or patches of pasture lands, along several of the tributaries of the Amazon, and Llanos—open flat plains generally flooded in the wet season—on the northern bank of the Orinoko. Unbroken forest also covers the country from Panama southwards by the Magdalena Valley along the western aspect of the Andes to Guayaquil. There is a very arid tract on the northeast coast of Brazil; but south of Cape San Roque the coast forests extend to 30° south latitude, "clothing all the valleys and hill-sides as far inland as the higher mountain ranges, and even penetrating up the great valleys far into the interior. To the south-west the forest country reappears in Paraguay, and extends in patches and partly wooded country till it almost reaches the southern extension of the Amazonian forests. The interior of Brazil is thus in the position of a great island plateau, rising out of, and surrounded by, a lowland region of ever-verdant forests." Of its Anthropoid life the Woolly Monkeys (Lagothrix), the Sakis (Pithecia), and the Uakaris (Brachyurus) are confined to its Amazonian forests. The Woolly Spider-Monkeys (Brachyteles) keep to the wooded coast-regions of South-east Brazil, while the Titis (Callithrix) do not range out of the tropics of South America. The Howlers (Alouatta), the Spider-Monkeys (Ateles), and the Capuchins (Cebus) roam nearly over the whole region—the first and last ranging from Costa Rica to Paraguay as well. The Spider-Monkeys indeed extend over to the west side of the Equatorial Andes, and in Guatemala across to the Pacific coast. No species of Monkey, however, is known to inhabit the western side of the Andes, to the south of the Gulf of Guayaquil.