Part 59

IX. THE HOODED SPIDER-MONKEY. ATELES CUCULLATUS.

Ateles cucullatus, Gray, P. Z. S., 1865, p. 733; id. Cat. Monkeys Brit. Mus., p. 42 (1870); Murie, P. Z. S., 1865, p. 739; Schl., Mus. Pays Bas, vii., p. 169 (1876).

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 {244}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."

X. THE LONG-HAIRED SPIDER-MONKEY. ATELES VELLEROSUS.

Ateles belzebuth, Geoffr., Ann. Mus., vii., p. 27, pl. xvi. (1806); Gray, Cat. Monkeys Brit. Mus., p. 44 (1870); Schl., Mus. Pays Bas, vii., p. 178 (1876).

Le marimonda, Humb. Obs. Zool., p. 325 (1811).

Ateles frontatus (nec Gray), Sclater, Nat. Hist. Rev., 1861, p. 509.

Ateles vellerosus, Gray, P. Z. S., 1865, p. 733; Reinh., P. Z. S., 1872, p. 797; Sclater, P. Z. S., 1873, pp. 5, 798, pl. ii.; Alston, in Godman and Salvin, Biol. Centr. Amer. Mamm., p. 10 (1879).

Ateles fuliginosus (nec Kuhl), Schl., Mus. Pays Bas, vii., p. 179 (1876).

Ateles pan, Schl., t. c. p. 180 (1876).

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 {245}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 {246}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 {247}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 {248}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.

THE BABOONS, GUEREZAS AND LANGURS. FAMILY CERCOPITHECIDÆ.

With the following account of the numerous species of the genera of this family, we come to consider the first section of the Old World, or Catarrhine Monkeys. These are {249}distinguished from their New World cousins, described in the previous pages, by many important and obvious characters. The partition dividing the nostrils is narrow, instead of broad, and the openings of the nostrils themselves are directed downwards and outwards. Certain genera possess also sacs formed by distensible folds of the skin in the cheeks. These "cheek-pouches" serve as a storing-place by the side of the jaws, for food which they cannot masticate at the moment. When this store is disposed of, the folds of skin come together again and give no indication of the presence of the pouch, which, moreover, when full does not interfere with the mastication of other food in the mouth, or with the utterance of the animal's usual cries.

The hind-limbs are never shorter than the fore-; they may be equal in length, but they are generally somewhat longer, the animal being more or less quadrupedal, or very partially erect in gait. Their thumb is not invariably present, but when it is, it is always opposable to its fellow digits. The great-toe is never rudimentary, and is never, as it is in Man, the longest, but is the shortest digit of the foot, and it is capable of free motion to and from the others. All of the digits possess nails. The length of the foot among this group approximates more to the proportions of the foot in Man. The hairs on the arms and fore-arms are directed downwards from the shoulder to the wrist.

The tail in this family varies very much; it may be long or short, or even externally absent, but it is never prehensile. All the species, however, possess "callosities," or hard fleshy pads--often of large size--on the buttocks or seat, which, like the naked skin of the face, are usually brilliantly coloured and often of large size. The perineal region and organs are at certain periods, especially in the females, subject to great turgescence and brilliant coloration.

{250}Besides these external characters, we find, on examining their bony structure, much variation in the skull. Some have a rounded forehead, the ascending portion of the lower jaw being high, broad, and flat, with a large facial angle; in others, we have great production of the upper jaw (the horizontal part of the lower jaw being greater than the ascending portion), and a low facial angle. The cerebral portion of the skull is long and flattened, and the palate long and narrow. The dental formula is I2/2, C1/1, P2/2, M3/3 = 32, that of the milk-teeth I2/2, C1/1, M (the forerunners of the permanent pre-molars) 2/2 = 20, exactly the same as in a Man. The outer lower incisors are equal to, or sometimes smaller than, the inner pair. The permanent canines--which are long and sharp--come in before, or with the posterior molars of both jaws. Between them and the incisors above, and between the canine and the anterior pre-molar below, occurs a gap (or diastema). The anterior upper pre-molar has its outer cusp modified and sharpened; the anterior lower pre-molar has the anterior margin of its crown so shaped as to work "as a scissors'-blade against the posterior edge of the upper canines." (Henley.) The crowns of the molar teeth are long from before backwards, and their fore and hind cusps are united by transverse ridges, a third being present in the same genera, on the posterior lower five-cusped molar.

The nasal bones are often ossified together to form one bone. The surface of the skull is in general oval and smooth, but in some of the Baboons there appear strong ridges over the eyes (hiding the forehead) and along the top of the head, being stronger, when present, in the male than in the female. The external orifice to the ear has a considerable bony tube, or meatus, a distinguishing character which is absent in the New {251}World Monkeys; their tympanic (or ear) cavity being close to the outer wall of the skull. The line of junction (or suture) between the upper jaw-bones, the pre-maxillary and the maxillary, remains unclosed until long after the permanent teeth have come in. Sometimes it remains unclosed throughout life. The foramen for the passage of the spinal-cord, and the condyles for the articulation of the skull with the neck, lie far back.

In the spinal column there are nineteen dorsal and lumbar vertebræ together. The number of caudal vertebræ varies greatly; in some there are as many as thirty-one, in others only three. The posterior ends of the ischiatic bones of the pelvis are rough, flattened, and broad, for the attachment of the fleshy callosities mentioned above.

The bones of the thigh and leg (femur and tibia) together, are longer than those of the arm and fore-arm (humerus and radius) together. The bones of the thumb are modified more for support and progression than for the actions of a true hand; by these modifications the movements of rotation (pronation and supination) are much restricted.

The ankle (tarsus) does not exceed one third of the length of the foot.

The stomach is simple, or but very slightly sacculated, in those genera which possess cheek-pouches; but is tripartite--the middle compartment being sacculated--in those that have not store-pockets in their mouths, "a groove with raised edges leading from the gullet-entrance to this middle compartment." The intestine has a cæcum, or blind diverticulum. "When laryngeal air-sacs are developed, they are formed by a single sac, with a median aperture--immediately beneath the epiglottis. This median air-sac is very large, extending down {252}over the front of the neck, and sending [in some genera] processes into the axillæ" or arm-pits. (Huxley.)