Part 56

Eriodes arachnoides, Geoffr., Mém. Mus., t. c. p. 160 (1828).

Brachyteles arachnoides, Gray, Cat. Monkeys Brit. Mus., p. 45 (1870).

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 {227}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.

THE SPIDER-MONKEYS. GENUS ATELES.

Ateles, Geoffr., Ann. Mus., vii., p. 262 (1806).

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 {228}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 {229}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 {230}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."

PLATE XXI.

{231}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.

I. THE VARIEGATED SPIDER-MONKEY. ATELES VARIEGATUS.

Ateles marginatus (nec Geoffr.), Humb. Obs. Zool., pp. 340, 354 (1811).

Ateles variegatus, Wagner in Schreb., Säugeth., i., p. 313 (1840); id. Abhandl. Akad. Münch., v., p. 420 (1847); Sclater, P. Z. S., 1870, p. 668; 1871, pp. 39, 225; Gray, Ann. Nat. Hist. (4), vi. (1870), p. 472.

Sapajou geoffroyi (nec Kuhl), Slack, Proc. Acad. Nat. Sci. Philad., 1862, p. 511 [= ].

Ateles bartletti, Gray, P. Z. S., 1867, p. 992, pl. xlvii.

Ateles melanochir, var. Gray, Cat. Monkeys Brit. Mus., p. 43 (1870, in part).

Ateles chuva, Schl., Mus. Pays Bas, vii., p. 175 (1876).

(Plate XXI.)

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 {232}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 {233}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.