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This sub-family embraces only one genus, which is very distinct from all the others. The Howlers are the largest of the South American Apes, and are characterised by their thick unwieldy body, their pyramidal head, and small facial angle, owing to their long, somewhat Dog-faced muzzle. The angle of the lower jaw is very large and massive, and their chief characteristic is the conspicuous thickening of the throat, owing to the great enlargement of the hyoid bones—which are widely inflated and cavernous—to form the curious vocal organ which the males of these animals possess, and by which their voice can be so augmented as to be heard at a distance of several miles.[1] The skull is truncated behind [ 190 ]in the male (less so in the female) for the reception of the vocal apparatus. Their incisor teeth are small and equal, the canines are prominent and have an oblique ridge across the crown from the outer front, to the inner hind, cusp, and the upper molars are large. The tail is powerful and prehensile, naked towards the tip, where it is tactile and very sensitive. The thumb is movable, the face is naked, and the chin bearded. Some have short, and some have long, fur over their bodies, but it is generally more plentiful about the head. In appearance they are the most unattractive and repulsive of the American Monkeys. Their intelligence is also of a very low order.

The roof of the brain-case is depressed; the plane of the opening for the passage of the spinal-cord from the brain is almost perpendicular to that of the base of the skull; the condyles for the articulation of the neck are situated as far back as possible. Sir William Flower, in his valuable monograph on the brain of Mycetes, has shown that the frontal lobes are small and the cerebral hemispheres only just cover the cerebellum. In regard to its grooves and convolutions, the main brain (cerebrum) of Mycetes can be distinguished from that of all other Monkeys. The whole organ is small as compared with the size of the animal; it wants the roundness and fulness of that of the Spider-Monkeys (Ateles) and of the Capuchins (Cebus). Its surface markings are comparatively few and simple, and depart remarkably from the ordinary type seen in the order. In the Old World Apes there is a striking similarity in the character of the surface markings of their cerebral hemispheres. There is a slight ascensive development from Cercopithecus towards Hylobates; and further complications overlying the same primitive type—such as large proportionate [ 191 ]size, and complexity of convolutions—are observed in the Chimpanzee and Gorilla, leading up to the brain of Man. Among the New World genera there is a much greater divergence. Among the Capuchins (Cebus), and among them only, there is a precise repetition of the Old World type; but in the genus Mycetes we have modifications in which there is no parallel among the Catarrhine (or Old World) series. There is an absence in its brain of signs of serial elevation; and it exhibits a great dissimilarity to all, even the lowest of the Old World forms, and to those American Monkeys, which in brain-character closely resemble Old World Apes. It shows an affinity in some of its more striking characters to such low forms of New World Apes as Nyctipithecus. The low type of brain is in keeping, as Sir William Flower further observes, with their surly and untameable disposition, and with the observation that their intelligence is of a very different order from that of their neighbours, the Spider-Monkeys and Capuchins of higher cerebral organisation.

"When Howlers are seen in the forest," remarks Mr. Bates, "there are generally three or four of them mounted on the topmost branches of a tree. It does not appear that their harrowing roar is emitted from sudden alarm; at least, it was not so in captive individuals. It is probable, however, that the noise serves to intimidate their enemies." The muscular power employed in giving vent to their cavernous roar appears to be small. Their food consists chiefly of fruits and leaves.

In colour the Howlers vary very much. The young of both sexes often differ from their parents, and the females from the males, and there is also great individual variation.

The geographical distribution of some of the species is very restricted, several of them being confined to a special district [ 192 ]of the Amazon, into which no other species intrudes. They are found, however, from Eastern Guatemala to Paraguay.


Alouatta, Lacép., Mém. Inst., iii., p. 490 (1801).

Mycetes, Illig., Prodr. Syst. Mamm., p. 70 (1811).

Stentor, Geoffr., Ann. Mus., xix., p. 107 (1812).

The characters of the genus Mycetes, which is the only one of the sub-family, are the same as those given above under the sub-family heading.

The genus contains six well-recognised species. According to Mr. Wallace the red and black species of the Amazon have females of the same colour as the males. Humboldt also remarks, speaking of the thousands of Arguatoes (M. seniculus) which he observed in the provinces of Cumana, Caracas, and in Guiana, that he never saw any change in the reddish-brown fur of the back and shoulders, either in isolated individuals or whole troops. Many of the species, however, do have the sexes of quite different colours.

The Howlers are semi-nocturnal in their habits, uttering their cries late in the evening and before sunrise, and also on the approach of rain. (Wallace.)

When a Mycetes is shot it always hangs to the tree, even if quite dead, and does not fall till the muscles of the feet and tail relax.

The species of this genus range through Central America, Colombia, and the Amazonian region, to Southern Brazil, Bolivia, and Paraguay.


Plate XVIII.

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Simia seniculus, Linn., Syst. Nat., i., p. 37 (1766).

Alouatta seniculus, Lacép., Mém. de l'Inst., iii., p. 489 (1800).

Stentor ursina (nec fig.), Humb. and Bonpl., Obs. Zool., v., p. 354 (1811).

Mycetes seniculus, Illig., Prod. Syst. Mamm., p. 70 (1811); Geoffr., Cat. Méth. Primates, p. 52 (1851); Schl., Mus. Pays Bas, vii., p. 156 (1876); Gray, Cat. Monkeys Brit. Mus., p. 39 (1870, part.).

Stentor seniculus, Geoffr., Ann. Mus., xix., p. 108 (1812).

Mycetes stramineus, Spix, Sim. et Vespert., Bras., p. 45, pl. 31 (1823; nec Geoffr.).

Mycetes chrysurus, Geoffr., Mém. Mus., xvii., p. 66 (1829).

Mycetes auratus, Gray, Ann. N. H., xvi., p. 220 (1845); id. Cat. Monkeys Brit. Mus., p. 40 (1870).

Mycetes laniger, Gray, Ann. N. H., xvi, p. 219 (1845); id. Cat. Monkeys Brit. Mus., p. 40.

Aluatta senicula, Slack, Proc. Acad. Nat. Sci. Philad., 1862, p. 517.

(Plate XVIII.)

Characters.—Head, neck, limbs and tail, dark chestnut-brown; back and sides golden-yellow; beard in the full-grown male long, the hair golden-yellow at the root, otherwise chestnut-brown; face naked, black; chest naked, the abdomen sparsely covered with long brown hairs.

The hair of the body is soft. The tail varies in colour in individual specimens, being sometimes, at its termination, of the same colour as the back, and sometimes bright golden-yellow. The mammæ are occasionally situated in the axillæ (or arm-pits). Length of body, 19½ inches; tail, 20 inches.

Young.—Of the same colour as the parents, only a little darker, the hair hard and rigid.

[ 194 ]Distribution.—Brazil; New Granada; Venezuela; Copataza river, Ecuador; Eastern Peru, along the Ucayali and Huallaga rivers.

Habits.—The Red Howlers always travel in large companies, keeping to the forests of the low lands and shores of the rivers. "We stopped," writes Humboldt, "to observe the Howling Monkeys, which, to the number of thirty or forty, crossed the road by passing in a long file from one tree to another upon the horizontal and intersecting branches." On another occasion the same celebrated naturalist records that "on approaching a group of trees, we perceived numerous bands of Arguatoes going as in a procession from one tree to another with extreme slowness. A male was followed by a great number of females, several of which carried their young on their shoulders. The uniformity with which the Arguatoes execute their movements is extremely striking. Whenever the branches of neighbouring trees do not touch, the male that leads the band suspends himself by the callous and prehensile part of his tail; and letting fall the rest of his body, swings himself till in one of his oscillations he reaches the neighbouring branch. The whole file performs the same action on the same spot. It is almost superfluous to add how dubious is the assertion that the Arguatoes and other Monkeys with prehensile tails form a sort of chain, in order to reach the opposite side of a river. We had opportunities, during five years, of observing thousands of these animals, and for this very reason we place no confidence in these stories."

"The Arguatoes are sometimes accused of abandoning their young, that they may be more free for flight when pursued by Indian hunters. It is said that mothers have been [ 195 ]seen taking off their young from their shoulders and throwing them down to the foot of the tree. I am inclined to believe that a movement merely accidental has been mistaken for one that was premeditated. The Arguatoes, on account of their mournful aspect and their uniform howlings, are at once detested and calumniated by the Indians."

Mr. Wallace, in a paper "On the Monkeys of the Amazon," in the "Proceedings of the Zoological Society," says: "Humboldt observes that the tremendous noise which these Howlers make can only be accounted for by the great number of individuals that unite in its production. My own observations, and the unanimous testimony of the Indians, prove this not to be the case, one individual alone making the howling, which is certainly of a remarkable depth and volume and curiously modulated; but on closely remarking the suddenness with which it ceases and again commences, it is evident that it is produced by one animal, which is generally a full-grown male."

The flesh of this species is very good to eat, and furnishes the principal food of the inhabitants of the regions in which it abounds.


Stentor caraya, Humb. and Bonpl., Obs. Zool., i., p. 355 (1811 ex Azara).

Mycetes barbatus, Spix, Sim. et Vespert., Bras., p. 46, pls. 32, 33 (1811).

Stentor niger (male), S. stramineus (female), Geoffr., Ann. Mus., xix., p. 108 (1812; nec Spix).

Mycetes caraya, Less., Sp. Mamm. Bimanes et Quadrum., p. 122 (1840); Gray, Cat. Monkeys Brit. Mus., p. 41 (part).

[ 196 ]Aluatta nigra, Slack, Proc. Acad. Nat. Sci. Philad., 1862, p. 518.

Mycetes niger, Thomas, P. Z. S., 1880, p. 394; Schl., Mus. Pays Bas, vii., p. 149 (1876).

Characters.—Male.—Hair rather long and entirely of a deep black; hair on the back of the head directed forward, meeting at right angles that of the forehead, which is directed backward, forming a well-marked semi-circular ridge. Length, 20 inches; tail, 17 inches.

Female and Young.—Pale straw-colour washed with black; the tips of the frontal ridge of hair black; at birth the young are entirely straw-colour.

Dr. Slack observes that, in the young, about the period of the second dentition, the hairs upon the mid-line of the back become black at their bases; soon after, the change takes place upon other parts of the body, the black gradually taking the place of the straw-colour, until the entire body in the adult male is of an intense black colour—the adult female having the coloration of the half-grown male.

Mr. Oldfield Thomas, who examined a specimen collected by Mr. Buckley, in Ecuador, points out that it agreed exactly with Humboldt's original description of the female of his Simia caraya, which he describes as having a black head and back, while the sides and belly are yellow. In all recent descriptions, however, the male is described as being nearly uniformly black, and the female uniformly yellow; so that Mr. Buckley's specimen appears to be just such an intermediate specimen as Humboldt described.

According to Prof. Schlegel, adult males sometimes have the black on the hands and feet mixed with yellow.

[ 197 ]Distribution.—This is the species of Howler which ranges furthest to the south. It occurs most abundantly in Southern Brazil, Paraguay, and Bolivia, but Mr. Bates records his having obtained a specimen at Villa Nova, on the Upper Amazons, which had come from above Borba, on the Rio Madeira. He did not, however, meet with it on any other part of the Amazon region. Mr. Graham Kerr saw it in troops on the banks of the Pilcomayo river.

Habits.—Like nearly all the Howlers, the present species is of a sulky disposition, in captivity slinking away out of sight when approached. The members of this genus are the only Monkeys which the Indians have not succeeded in taming. They rarely survive their captivity many weeks.


Simia beelzebul, Linn., Syst. Nat., i., p. 37 (1766).

Mycetes rufimanus, Kuhl, Beitr. Zool., p. 31 (1820).

Mycetes discolor, Spix, Sim. et Vespert., Bras., p. 48, pi. xxxiv. (1823).

? Colobus chrysurus, Gray, Ann. Nat. Hist., xvii., p. 77 (1866).

Mycetes beelzebul, Gray, Cat. Monkeys Brit. Mus., p. 41 (1870); Schl., Mus. Pays Bas, p. 150 (1876).

Characters.—Black, slightly washed with yellow on the under side of the body and inner side of the limbs; hairs of the body soft, brown at the roots, black at the tips; hands and feet variable, reddish-yellow or reddish-brown, or grey, or black. Upper surface and tip of the tail, spot in front of the ears, and on the knees, reddish-yellow. Length of the body, 17½ inches; tail, 18½ inches.

This species differs from the Black Howler (A. nigra) by the [ 198 ]brown colour of the roots of the hair; and from the species next to be described—the Brown Howler (A. ursina)—by the length of the fur and the absence of the reddish-brown tips to the hairs.

Distribution.—Apparently confined to the Lower Amazon, in the vicinity of Para.

Habits.—The same as those of the species already described.


Stentor ursina, Humb. and Bonpl., Obs. Zool., i., pl. 30 (fig. nec descr.; 1811).

Stentor flavicauda, Id. t. c. p. 355 (1811).

Stentor ursinus, Geoffr., Ann. Mus., xix., p. 108 (1812).

Stentor fuscus, Geoffr., t. c. p. 108 (1812).

Mycetes fuscus, Kuhl, Beitr. Zool., p. 29 (1820); Spix, Sim. et Vespert., Bras., p. 43, pl. 30 (1823).

Mycetes bicolor, Gray, Ann. N. H., xvi., p. 214 (1845); id. Cat. Monkeys Brit. Mus., p. 40 (1870).

Mycetes ursinus, Is. Geoffr., Cat. Méth. Primates, p. 55 (part., 1851); Gray, Cat. Monkeys Brit. Mus., p. 39 (1870); Schl., Mus. Pays Bas, vii., p. 155 (1876).

Aluatta ursina, Slack, Proc. Acad. Nat. Sci. Philad., 1862, p. 517.

Mycetes flavicauda, Schl., t. c. p. 147 (part., 1876).

Characters.—General colour shining yellowish-red, or dark brownish-yellow; hairs rather rigid, black with yellowish tips; hairs of the shoulder ringed with black. When half-grown the limbs and tail are very dark brown, nearly black; tail shorter than the body, olive black, with two yellow lateral stripes. Length of the body, 23 inches; of the tail, 22 inches.

[ 199 ]Young.—Black, with the tips of the hairs of the body yellowish-brown; base of the tail and the surrounding region reddish-brown.

This species is remarkable for great variation in colour. The young at first sight, as Dr. Slack has pointed out, appear to be of an intense black colour, but upon a closer examination, the hairs, more especially those of the back and sides of the head, are found to be tipped with reddish-brown. As the animal becomes older the black gradually vanishes, a yellowish-brown colour appearing in its place, until in the adult the only remains of the black are to be found in a few annulations in the hairs of the shoulders.

The skins are an article of commerce, for saddle cloths and saddle coverings.

Distribution.—The Rio Negro and Upper Amazonia. Mr. Bates remarks that this is the only species seen in this region.


Mycetes villosus, Gray, Ann. Nat. Hist., xvi., p. 220 (1845); id. Cat. Monkeys Brit. Mus., p. 41 (1870); Sclater, P. Z. S., 1872, p. 5, figs, 1 and 2; Alston, in Godm. and Salvin, Biol. Centr. Amer. Mamm., pp. 3 and 5, pl. i.

Characters.—Differs from M. niger by its abundant, long, and soft hairs, which below, towards their bases, show a rufescent tinge, and by the frontal hairs being sometimes directed downwards at the base, instead of upwards; hair on cheeks under the ears, brownish.

Male.—Entirely black.

Female and Young.—Also quite black, like the adult male, [ 200 ]instead of being pale yellow, like the corresponding age and sex of A. nigra, and having also the hair shorter and not so glossy.

Distribution.—This Howler is known only from the virgin forests of the eastern and north-eastern portions of Guatemala. Mr. Osbert Salvin has given the following account of this species. "The Mycetes of Guatemala is commonly known as the 'Mono.' It is abundant throughout the virgin forests of the eastern portion of the Republic, but is unknown on the forest-clad slopes which stretch towards the Pacific Ocean. In the former region it is found at various altitudes over a wide expanse of country. I have heard its cry on the shores of the lake of Yzabal; and all through the denser forests of the valley of the River Polochic it is very common, from the steep mountain road which lies between the upland village of Purulá and S. Miguel-Tucuru, and especially in the wilderness of uninhabited forest, which stretches from Teleman to the lake of Yzabal. In the unbroken forest-country which occupies the whole of the northern portion of Vera Paz, from Coban and Cahabon to the confines of Peten, it is also abundant; for seldom an hour passes but the discordant cry of the Mono strikes upon the ear of the traveller, as he threads the lonely path to Peten. The elevation of this district varies from 700 to 3,000 feet, and the Mycetes is found at all elevations. When travelling through the forest in 1862, I was dependent for the animal food, to supply my party of Indians, entirely upon my gun, and Monos contributed not a little to the larder. The Indians eat Monkey without demur, but the meat looks dark and untempting. For my own part I far preferred the delicate Tinamou or Curassow, a sufficient supply of which never failed for my own consumption. Perhaps there is no district in Vera Paz where Monos are more abundant than the mountains of [ 201 ]Chilasco, a cold and damp region, elevated at least 6,000 feet above the sea, but where the forest-growth is of the densest description and trees of the largest size abound. It was here that the specimens were obtained that are now in the British Museum."

Habits.—These animals are found in small companies of five or six. They are usually met with on the upper branches of the highest trees, and when disturbed crawl sluggishly along the boughs. "The wonderful cry whence Mycetes gets its trivial name of Howling Monkey is certainly most striking; and I have sometimes endeavoured to ascertain how far this cry may be heard. It has taken me an hour or more to thread the forest undergrowth from the time the cry first struck my ear to when, guided by the cry alone, I stood under the tree where the animals were. It would certainly not be over estimating the distance to say two miles. When the sound came over the lake of Yzabal, unhindered by trees, a league would be more like the distance at which the Mono's cry may be heard." (O. Salvin.)

To this species, we believe, belongs the following description given by Captain Dampier: "The Monkeys that are in these parts are the ugliest I ever saw. They are much bigger than a Hare, and have great Tails about two Foot and a half long. The under side of their Tails is all bare, with a black hard Skin; but the upper side and all the Body is covered with coarse, long black staring Hair. These Creatures keep together, twenty or thirty in a company, and ramble over the Woods, leaping from Tree to Tree. If they meet with a single Person they will threaten to devour him. When I have been alone I have been afraid to shoot them, especially the first Time I met them. They were a great company, dancing [ 202 ]from Tree to Tree over my Head; chattering and making a terrible Noise; and a great many grim Faces, and shewing antick Gestures. Some broke down dry Sticks and threw at me; ... at last one bigger than the rest came to a small Limb just over my Head; and leaping directly at me made me start back, but the Monkey caught hold of the Bough with the tip of his tail; and there continued swinging to and fro, and making mouths at me.... The Tails of these Monkeys are as good to them as one of their hands; and they will hold as fast by them.... The Females with their young ones are much troubled to leap after the Males; for they have commonly two: one she carries under one of her Arms, the other sits on her Back, and clasps her two Fore-Paws about her Neck. These Monkeys are the most sullen I ever met with, for all the Art we could use would never tame them.... These Monkeys are very rarely or (as some say) never on the Ground."


Mycetes palliatus, Gray, P. Z. S., 1848, p. 138, pl. vi.; Frantz., Wiegm. Arch., xxxv., p. 254 (1869); Gray, Cat. Monkeys Brit. Mus., p. 40 (1870); Scl., P. Z. S., 1872, p. 7; Schl., Mus. Pays Bas, vii., p. 152 (1876); Alston, in Godm. and Salvin, Biol. Centr. Am. Mamm., p. 4 (1879).

Aluatta palliata, Slack, Proc. Acad. Nat. Sci. Philad., 1862, p. 519.

Characters.—Face naked; hair of forehead short, reflexed, forming a slight crest across the middle of the head; hairs of the back of the head rather longer; those of the cheeks few, short and grey; those of the fore neck lengthening into a short beard. General colour brownish-black; middle of back and [ 203 ]upper part of sides, yellowish-brown; lower part of sides brownish-yellow, lengthened into a mantle; arms, legs, and tail black. Length, 19½ inches; tail, 20¾.

The late Mr. Alston, in describing the Mammals of Central America, in Messrs. Godman and Salvin's monumental work, "Biologia Centrali-Americana," observes that "this Howler presents considerable variety in the depth of the black or brown-black ground-colour, and in the extent of the fulvous tints of the flanks and loins. Dr. v. Frantzius states that the Howlers which he saw in Costa Rica were darker than is indicated by Dr. Gray's description; and in several of the Panama examples the light markings are much reduced, but in others they are quite as conspicuous as in the Nicaraguan types." Mr. Alston, therefore, agrees with Prof. Schlegel, that the variation does not depend on locality.

Distribution.—Shores and islands of the lake of Nicaragua; Costa Rica; Panama; Islet of Hicaron, at the southern extremity of Quibo Island, off the Coast of Veragua. South of the Isthmus of Panama, the Red Howler (A. senicula) replaces the Mantled Howler.

Habits.—The habits of the Mantled Howler do not differ widely from those of the species already described. It prefers the highest branches of the trees of the dense forests; and is harmless to the plantations of the natives. In disposition it is dull and melancholy, and is rarely kept in confinement. It is said, however, to reconcile itself to captivity more than some of the others referred to in previous pages. According to Dr. v. Frantzius, a tame male individual of this species was observed to howl whenever rain-clouds gathered, and also regularly at five o'clock every morning.

  1. See the figures in Flower and Lydekker, Mammals, p. 711.