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This family embraces the typical Platyrrhine Monkeys, and to it belongs the great majority of the American species. As already pointed out (p. 127) their nose is flat, and the partition between the nostrils, which open sideways, is very broad, and separates them widely. They are essentially quadrupedal, and walk with the soles of both pairs of limbs flat to the ground. The Spider-Monkeys occasionally, however, assume an erect posture. "They all possess tails, and in some genera (e.g., Ateles) this organ becomes very flexible and muscular, and the under surface of its curled extremity is devoid of hair and highly sensitive. The tail thus modified is a powerful prehensile organ and serves for a fifth hand." (Huxley.) In these [ 151 ]Monkeys there are no cheek-pouches, nor ischial callosities. Except in the Spider-Monkeys the hind-limbs are longer than the fore-; "while the thumb, even where it is best developed, is capable of but a partial opposition to the other fingers, bending almost in the same plane with the latter, so as to be more like a fifth finger." (Mivart.) Nevertheless, all its muscles, except the long flexor, are present. The great-toe is large and can be moved from and to the side of the other digits, but is not opposable to them.

The skull is smooth and has no muscular crests; the external bony tube to the ear is not ossified. The two extremes in its form are presented by the Howling Monkeys (Alouatta) and the Squirrel-Monkeys (Chrysothrix), as pointed out by Professor Huxley in his "Anatomy of Vertebrated Animals": "In the former the face is very large and prominent, with a low facial angle. The roof of the brain-case is depressed; the plane of the occipital foramen [for the passage of the spinal cord] is almost perpendicular" to the axis of the base of the skull. "In Chrysothrix, on the contrary, the face is relatively small, with a high facial angle; the brain-case is moderately arched;" and the plane of the occipital foramen is horizontal.

The dentition of the Cebidæ is very characteristic of the family. The dental formula is I 2/2, C 1/1, P 3/3, M 3/3 and the teeth thirty-six in all—a larger number than is found in any of the Old World forms, or in the species of the last family (the Hapalidæ); for they possess an extra pre-molar tooth above and below on each side. Their molar teeth are four-cusped; and in the upper molars of the Spider-Monkeys (Ateles) and of the Howlers (Alouatta) there is an oblique cusp, such as is found in the molars of the Lemuroidea, joining the hind inner to the front outer cusp. Among the Cebidæ the brain varies [ 152 ]very much; the posterior lobes of the main brain (or cerebral hemispheres, which are almost always convoluted) are also almost always so large as to entirely cover over the cerebellum (or hind brain), a relation which does not exist between these two regions of the brain in the Lemuroidea. The cerebellum, however, in the Howlers is slightly uncovered. The absolute size of the brain never, in any Ape, approaches that of Man. None of the Cebidæ attain the size of even the medium-sized Old World Apes.

The Cebidæ are all arboreal, and strictly confined to the forest regions of Tropical America, from the southern part of Mexico to about the parallel of 30° S. lat. They are divided into four sub-families, namely: The Douroucolis, or Night-Monkeys (Nyctipithecinæ); the Saki Monkeys (Pitheciinæ); the Howlers (Mycetinæ); and the Capuchin Monkeys (Cebinæ).


The Night-Monkeys are small and elegant animals covered with long hair, and having long bushy tails, which are not prehensile, although they can be curled round a branch of a tree. The caudal vertebræ in these creatures are consequently not flattened from above downward, as is the case in the prehensile-tailed groups, but rounded. Their lower incisor teeth are set vertically and their thumb is fairly well developed.

This sub-family contains three genera, the Squirrel-Monkeys (Chrysothrix); the Whaiapu-Sais, or Titis (Callithrix); and the typical Night-Monkeys, or Douroucolis (Nyctipithecus).


Chrysothrix, Kaup., Thierreich., i., p. 51 (1835).

[ 153 ]The Saimiris, or Squirrel-Monkeys, are very beautiful and active little animals, characterised by their soft, close, and erect fur, and especially in having the head produced posteriorly. The face is relatively small and has a high facial angle. The eyes are large, directed forwards, and set very close together. The ears are large; and the nose has a very broad partition between its nostrils. The tail is long, round, and covered with short hair; but tufted at the extremity and non-prehensile.

As regards the skeleton, the skull is elongated, and the arched cranial portion prolonged backwards, the length of the base of the skull being shorter than the cerebral cavity. The facial portion of the skull is relatively smaller and the cranial larger even than in Man; this character being, however, common to all the smaller representatives of particular groups, and "obviously necessary to provide the requisite amount of brain-space." (Mivart.) The angle of the lower jaw is narrow behind. The bony partition between the nostrils is very thin and membranaceous; and that between the large orbits is also thin and imperfect. The lower incisor teeth are vertical, and in regular series with the canines, and the latter are well developed. No Primate has the teeth placed in one uninterrupted series except Man; but there is always a small interval between each upper canine and the adjacent incisor, and between each lower canine and the adjacent pre-molar.

The skeleton of the hand is one-fifth of the length of the spinal column. The wrist-bones are nine in number, the central—os centrale—being present as in the majority of Monkeys. In Chrysothrix and in Nyctipithecus also, the thumb is proportionately shorter than in any other genus, except among the Spider-Monkeys (Ateles), and the Old World [ 154 ]Guerezas (Colobus). In the length of their foot the members of this genus approximate to the proportion existing in Man; and its length, compared with that of the hand, is greater in Chrysothrix than in any other group of Monkeys.

The cerebral hemispheres project beyond the hind brain (cerebellum) to a greater relative extent than in any other mammal, namely, to one-fifth of their total length. (Huxley.) The external surface of the cerebral hemispheres is almost as little convoluted as in the Marmosets and Tamarins, in which it is almost quite smooth, yet on the inner faces of the hemispheres the more important grooves (sulci) are present. The opening for the passage of the spinal cord lies nearly in the middle of the base of the skull, whereas in other genera it is situated closer to the hinder region.

The Squirrel-Monkeys are entirely arboreal, and found in most of the tropical regions from Costa Rica to Brazil and Bolivia, being among the commonest of the Anthropoids of the American forests. They are diurnal, and feed chiefly on insects; but they will also often attack and devour small birds.


Saimiris usta, Is. Geoffr., Arch. Mus., iv., p. 15, pl. 1 (1844).

Saimiris ustus, Bartlett, P. Z. S., 1871, p. 219; Sclater, P. Z. S., 1872, p. 688, fig. of head.

Chrysothrix ustus, Gray, Cat. Monkeys Brit. Mus., p. 53 (1870).

Saimiri sciureus (nec L.), Schl., Mus. Pays Bas, vii., p. 242 (1876, pt.)

Characters.—Face white; head grizzled grey, minutely punctulated with black, the hairs grey with black tips; outer side of fore-arm grizzled grey, but in some species golden; back [ 155 ]grizzled grey, washed with golden, the tips of the hairs black; tail short, thick and grey, but with the tip black.

Distribution.—The forests of Bolivia and Brazil. This is a common species, inhabiting the whole of the Peruvian Amazons, and may be met with on every stream. (E. Bartlett.)

Habits.—Arboreal and gregarious, moving about in large numbers through the forest, feeding on insects—chiefly orthoptera and spiders—small birds, and fruits.


Callithrix entomophagus, d'Orb., Voy. Amér. Mér., iv., Mamm. pl. 4 (1836).

Callithrix boliviensis, d'Orb., Nouv. Ann. Mus., iii., p. 89 (1834).

Saimiris entomophagus, d'Orb., Voy. Amér. Mér., iv., Mamm., text, p. 10 (1847); Is. Geoffr., Cat. Méth. Primates, p. 38 (1851).

Saimiri entomophagus, Schl., Mus. Pays Bas, vii., p. 246 (1876).

Chrysothrix sciurea (nec L.), Frantz. in Wiegm. Arch. f. Nat., xxxix., p. 260 (1869).

Chrysothrix entomophagus, Wagn., Ann. Nat. Hist., xii., p. 42 (1843); Gray, Cat. Monkeys Brit. Mus., p. 53 (1870).

Characters.—Face grey, washed with yellow; ears haired; head black; hairs of back black, with long yellow tips, or yellow with black tips, producing a shade of brown washed with golden; outer side of upper part of arms and legs yellow, peppered with black; throat, under surface of body and inside of limbs yellowish-grey; tail long, black.

[ 156 ]In some species the upper part of the head has a shade of yellow, caused by the colour of the lower half of the hairs showing through the black tips.

Distribution.—Bolivia; Veragua, Central America; and the warmer regions of Costa Rica, where it inhabits the humid forests.


Simia sciurea, Linn., Syst. Nat., i., p. 43 (1766); Humb., Obs. Zool., p. 334 (var. cassiquiarensis).

Callithrix sciureus, Geoffr., Ann. Mus., xix., p. 113 (1812).

Saimiri sciureus, Cuv., Reg. An., p. 103, pl. 1 (1829); Schl., Mus. Pays Bas, vii., p. 242 (1876).

Chrysothrix lunulata, Geoffr., Arch. Mus., iv., p. 18 (1844).

Chrysothrix sciurea, Wagner in Schreb., Säugth. Suppl., v., p. 120, pl. 9, (1855); Gray, Cat. Monkeys Brit. Mus., p. 53 (1870); Sclater, P. Z. S., 1880, p. 395.

Chrysothrix nigrivittata, Wagn., Abh. bay. Ak. München, v., p. 461.

Characters.—Smaller than the two preceding species; face greyish-white; chin round and prominent; head blackish-grey; back grey, or grey washed with gold, the basal part of the hairs golden and the tips black; outer side of the fore-arm yellow; tail long, slender, grizzled grey, with the tip black. Length of the body, 10 inches; of the tail, 14 inches.

Certain females, examined by Dr. Sclater, had a distinct black line along the side of the crown above each ear and extending in front, down the side of the face, nearly to a level [ 157 ]with the angle of the mouth; but Mr. Buckley says the Indians consider the black lines to be merely a sign of age.

Distribution.—This species has an extensive range, being found on both banks of the Amazon, Rio Negro, and on the Copataza river; also in Guiana, Surinam, and Colombia, near Bogotá.

Habits.—Like its congeners, the Common Squirrel-Monkey is arboreal, going about in large flocks. Their food consists of insects and fruits. Mr. Bates observes that the "pretty little Chrysothrix sciureus contents itself with devouring what fruit it can on the spot," thus differing from certain species of Cebus, which destroy more than they eat, and when about to return to the forest, carry away all they can in their hands or under their arms.

Mr. Darwin has remarked in his "Expression of the Emotions in Man and Animals," that "with Monkeys the expression of any painful emotion is not easily distinguished from that of anger." "Humboldt," he adds, "also asserts that the eyes of the Callithrix sciureus 'instantly fill with tears when it is seized with fear'; but when this pretty little Monkey in the Zoological Gardens was teased, so as to cry out loudly, this did not occur. I do not, however, wish to throw the least doubt on the accuracy of Humboldt's statement."

This species is a great favourite wherever it has been kept in captivity. It is very bright coloured, has a baby-like face, large and bright eyes, and most gentle manners. These Monkeys are very sensitive to cold, and when a sudden fall in the temperature takes place, they huddle close together, clasping each other with their arms, and embracing their neighbours and themselves with their long tails.

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Saimaris sciurea ? (nec Linn.), Sclater, P. Z. S., 1856, p. 139.

Chrysothrix sciurea (nec Linn.), Scl., N. H. Rev., 1861, p. 510; Frantz. Arch. f. Naturg., xxxv. (1), p. 260.

Chrysothrix œrstedi, Reinh. Vidensk. Medd. Nat. For. Kjöbenh., p. 157, pl. iii. (1872); Alston, in Godm. et Salv., Biol. Centr. Am. Mamm., p. 16, pl. ii. (1879).

Saimiris entomophaga, Sclater, P. Z. S., 1872, p. 3 (nec d'Orb.).

Saimiri örstedii, Schl., Mus. Pays Bas, vii., p. 245 (1876).

Characters.—Differs from C. sciurea in having the top of the head black, the back and sides shining red, and the limbs olive.

Distribution.—Panama, Guatemala, Costa Rica, especially their hotter districts,—being particularly abundant in the Valley of Terraba and on the plain of Piris.


Callithrix, Geoffr., Ann. Mus., xix., p. 112 (1812).

This genus is intermediate between the Squirrel-Monkeys and the typical Night-Monkeys. In the Titis, sometimes known by the name also of Whaiapu-Sai Monkeys, the fur is soft, the head small, depressed, and not produced backward as in Chrysothrix; the tail is long and bushy; the eyes are small, and the orbits intermediate in size between those of the last and the next genus; the nasal partition is broad, and the ears large. The canine teeth are small, and the angle of the lower jaw expanded, somewhat as in the Howlers (Mycetes), though to a less extent.

[ 159 ]The Titi Monkeys are diurnal animals, arboreal and gregarious, very lively in disposition, noisy and agile, living on fruit, insects, birds' eggs, and even small birds. They range all over South America, from Panama to the southern limits of the forest regions.


Cebus torquatus, Hoffm., Mag. Ges. Nat. Freund. Berlin, x., p. 86 (1807).

Simia lugens, Humb., Obs. Zool., i., p. 319 (1811).

Callithrix lugens, Geoffr., Ann. Mus., xix., p. 113 (1812).

Saguinus vidua, Lesson, Species Mamm. Bimanes et Quadrum., p. 165 (1840).

Callithrix torquatus, Geoffr., t. c. p. 114; Gray, Cat. Monkeys Brit. Mus., p. 55 (1870).

Callithrix torquata, Schleg., Mus. Pays Bas, vii., p. 235 (1876).

Characters.—Head round; face short; ears short, nearly naked; nose flat. Fur soft and woolly, intermixed with many long, stiff, dark reddish-brown hairs,—the hairs red at the base, and black at the tips; forehead black; crown of head dark brown; a narrow band round the face, white; a narrow collar round the neck, reddish-white; hands white; hair of feet red at the base, but black at the tips. Length of the body, about 12 inches.

Distribution.—Confined to the upper reaches of the Rio Negro, Brazil.

Habits.—This species, often known under the name of the Widow Monkey, is said to be very gentle in disposition. [ 160 ]When approaching to capture insects or small birds, which form its prey, it becomes keen and excited, but at other times it appears to be dull and listless. They roam about in flocks of about half a dozen individuals, on the large branches of the great forest trees. They are noisy animals, and in the early morning they make the forest resound with their yelping cries.


Callithrix cuprea, Spix, Sim. et Vesper. Bras., p. 23, pl. 17, (1823); Gray, Cat. Monkeys Brit. Mus., p. 54 (1870); Schleg., Mus. Pays Bas, vii., p. 236 (1876); Thomas, P. Z. S., 1880, p. 394.

Callithrix discolor, Is. Geoffr., C.R., xxvii., p. 498 (1848); id. Cat. Méth. Primates, p. 41 (1851); id. Arch. Mus., v., p. 551, pl. 28; Wagner in Schreb., Säugeth. Suppl., v., p. 114 (1855).

(Plate XIV.)

Characters.—Fur soft and woolly, mixed with numerous long stiff hairs; face black; back grizzly blackish-grey in colour; tail the same but darker; the basal part and tips of the hairs grey, with an intermediate band below the tips, black; tip of the tail sometimes white; the cheeks, throat, hands, feet, legs, and the under side of the body, dark reddish bay; the ears coppery-red.


Plate XIV.


[ 161 ]Distribution.—This species is found throughout the whole of the Peruvian Amazons, though not in very large numbers—indeed, it is said to be rare. It has been recorded from Cashiboya on the Ucayali, and Santa Cruz on the Huallaga. Mr. O. Thomas mentions his having examined twelve specimens from the Copataza river, and one from Andoas in Ecuador. Of these he says: "The Andoas specimen, which is a male, differs from the rest in having the fur on the back of a dirty orange-grey colour, without annulations, instead of being of a bright annulated black and white. One of the others, a female, shows a tendency to this condition of the hair, which is, therefore, probably a seasonal change, as the Andoan specimen was shot in September, while the others were obtained between December and February."


Simia amicta, Humboldt, Obs. Zool., i., p. 357 (1811).

Callithrix amicta, Spix, Sim. et Vespert. Bras., p. 19, pl. xiii. (1833).

Callithrix amictus, Geoffr., Ann. Mus., xix., p. 114 (1812); Gray, Cat. Monkeys Brit. Mus., p. 54 (1870).

Callithrix torquata, Schl., Mus. Pays Bas, vii., p. 235 (part, 1876).

Characters.—Agrees with the last species in the character of the fur; but the general colour is black, washed with rufous; the forehead is black; the chest has a pure white spot; the hands are white, but the feet black; the tail has the hairs entirely black throughout.



Callithrix cinerascens, Spix, Sim. et Vespert. Bras., p. 20, pl. 14 (1823).

Callithrix donacophilus, d'Orb., Voy. Amér. Sud, iv., p. 10, pl. 5 (1826); Gray, Cat. Monkeys Brit. Mus., p. 55 (1870).

Callithrix donacophila, Geoffr., Cat. Méth. Primates, p. 41 (1851); Schl., Mus. Pays Bas, vii., p. 240 (1876).

[ 162 ]Characters.—Fur long and similar in character to that of C. torquata; chest and under side of body pale grey or dark reddish-grey; hands and feet grey; back of the same colour; tail mottled grey,—the hairs being grey, with black tips.

In some species the fur varies from dark grey washed with rufous, to almost white, the red wash, where it occurs, sometimes deepening, or almost vanishing.

Distribution.—Mr. Bates observed this species at Serra dos Parentins, in the Lower Amazon Region above the confluence of the Tapajos with the Amazon. It also extends to Bolivia and Peru.


Cebus moloch, Hoffman, Mag. Gesell. Berlin, x., p. 97 (1807).

Callithrix moloch, Geoffr., Arch. Museum, iv., p. 33, pl. 3(1844), id., Ann. Mus., xix., p. 114 (1812); Gray, Cat. Monkeys Brit. Mus., p. 55 (1870).

Characters.—Differs from the Reed Titi in having the cheeks, chest, and belly red. Hands and feet of the same colour as the back, grey.

The cerebral convolutions of this animal are, according to M. C. Dareste, exactly those of a "Maki," or Lemur.

Distribution.—Throughout Brazil.


Callithrix discolor, Verreaux, M.S. (nec Geoffr.).

Callithrix ornata, Gray, Ann. and Mag. Nat. Hist., xvii., p. 57 (1866).

Callithrix ornatus, Gray, Cat. Monkeys Brit. Mus., p. 55 (1870).

[ 163 ]Characters.—General colour black and grey, grizzled; forehead and ears white, instead of black as in C. caligata, or coppery-red as in C. cuprea; temples, cheeks, throat, under side of body, and inner side of legs, bright chestnut; hands and feet grey; tail black, with a grey tinge,—the hairs being grey, with a dark ring near the tip of each; hands and feet the colour of the back.

Distribution.—U. S. Colombia; vicinity of Bogotá.

Habits.—This species is arboreal, like the other members of its genus, and it is said to be nocturnal. It spends the day rolled up very much as many of the Lemurs do.


Callithrix personatus, Geoffr., Ann. Mus., xix., p. 113 (1812); Spix, Sim. et Vespert. Bras., p. 18, pl. 12 (1823); Gray, Cat. Monkeys Brit. Mus., p. 56 (1870).

Callithrix brunnea, Wagner, Arch. f. Naturg., 1842, i., p. 357 (ex Natterer, MSS.).

Pithecia melanops, Vigors, Cat. Coll. Zool. Soc., p. 6.

Callithrix personata, Schl., Mus. Pays. Bas, vii., p. 231 (1876).

Characters.—Size larger than that of the other Titis. Style of fur the same as in the previous species, but longer, and the long stiff hairs more bristly; general colour black, mottled with grey rings on the hairs; back grizzled grey; entire head, hands, feet, and lower part of limbs, black; chest, under side of the body, and tail dark ashy-grey, the latter washed at the base, sometimes extensively, with rufous, and grey towards the tip below.

Female.—Body strongly washed with whitish-yellow, and the tail with rufous; forehead between the ears, black.

[ 164 ]Distribution.—Upper Amazon. Of all the species of the genus, this ranges furthest to the south—to 14° S. lat.


Callithrix nigrifrons, Spix, Sim. et Vespert. Bras., p. 21, pl. 15 (1823); Gray, Cat. Monkeys Brit. Mus., p. 56 (1870); Schl., Mus. Pays Bas, vii., p. 232 (1876).

Characters.—Nearly allied to the Masked Titi (C. personata), but distinguished by the nearly white back of the head and nape of the neck, and by the hairs at the base of the tail being entirely red.

Distribution.—Upper Amazonia.


Callithrix castaneoventris, Gray, Ann. and Mag. N. H., xvii., p. 58 (1866); id., Cat. Monkeys Brit. Mus., p. 56 (1870).

Callithrix caligata, Wagner, Arch. f. Naturg., 1842, i., p. 454 (ex Natterer, MSS.); Schl., Mus. Pays Bas, vii., p. 237 (1876).

Characters.—Fur of the same nature as in C. cuprea, black, ringed with grey; face grizzled, whiskers, throat, chest, under side of the body, and inner surface of the limbs reddish-chestnut; outside of the limbs grizzled, washed with rufous; forehead, hands, feet and tail black; tip of the tail paler.

Distribution.—Paraguay and Brazil; Borba, Rio Madeira.

The two following species may be distinguished from those already described by having their soft woolly fur entirely free from the long bristly hairs, which were dispersed through the fur of the others.

[ 165 ]


Callithrix melanochir, Neuwied, Beitr., ii., p. 114, et Abbild., iv.; Gray, Cat. Monkeys Brit. Mus., p. 57 (1870); Schl., Mus. Pays Bas, vii., p. 233 (1876).

Characters.—General colour red, but the crown of the head, the throat, and inner side of the limbs, mixed black and grey; the hands and feet black.

Distribution.—This species has been recorded from Bahia, on the east coast of Brazil.


Callithrix gigot, Spix, Sim. et Vespert. Bras., p. 22, pl. 16 (1823); Schl., Mus. Pays Bas, vii., p. 234 (1876); Weldon, P. Z. S., 1884, p. 6.

Callithrix gigo, Gray, Cat. Monkeys Brit. Mus., p. 57 (1870).

Characters.—Hair about two inches long, soft and slightly woolly over the trunk; hair on the forehead shorter and more thickly set; that over the limbs short and loose. General colour of the back reddish-grey behind, more ashy over the forehead and limbs; the hair black at the base, cream-coloured further up, the tips ringed with chestnut and black. Muzzle and chin black, with a few short, strong, white hairs; a black line along the nose and round the eyes; the eyelids white; the eye-lashes and long eye-brows black; forehead thickly covered with loose grey hairs, slightly tipped with black; a faint ridge across the brow between the ears; the ears black, covered with soft black hairs, except for a small grey tuft at their hind outer angle. In front of the ears a light grey band over the cheeks, continued above on to the forehead, below to the chest; throat naked, light pink; under surface [ 166 ]of the limbs pale grey; the hands and feet black; tail red, the hair bushy at its base. Length of the body, 14 inches; of the tail, 13½ inches. (Weldon.)

Cæcum with dilated end; liver more divided than in C. moloch; the two halves (rami) of the lower jaw enormously deep, resembling those of the Howlers (Mycetes).

Distribution.—Brazil; Bahia, and the country between the Parahyba and the mountains to the north of the Bay of Rio de Janeiro.

Habits.—This species is very rare, and nothing is known of its habits.

Professor Weldon writes, in his paper in the "Proceedings of the Zoological Society," referred to above: "Sir W. Flower has suggested to me that the enormous depth of the ramus of the mandibles in this Callithrix pointed to the existence of some arrangement resembling that of Mycetes. It was difficult to determine this point in a young female; but the swollen condition of the thyroid, together with the existence of a patch of ossification on each side, seem to show the possible existence of a howling apparatus in the male."


Nyctipithecus, Spix, Sim. et Vespert. Bras., p. 24 (1823).

The members of this genus, usually called "Douroucolis," are small animals, somewhat Lemurine in appearance, possessing a short, thick body, a rounded head produced behind, and a short, round face, encircled by a ruff of whitish fur. The muzzle is not prominent; the mouth and chin are small; the [ 167 ]ears are very short, scarcely appearing above the hair of the head; the eyes are enormous and yellowish in colour, imparting to them the staring expression of nocturnal animals of prey. Their tail is bushy, moderately long and non-prehensile; and the nostrils are separated by a narrower partition than in the other genera of the sub-family. Their physiognomy reminds one of an Owl or Tiger-cat (Bates). They are covered with close, soft, woolly fur.

In the skull the orbits are enormously large and closely approximated, but yet separated by a complete bony wall; the nostrils, on the other hand, though separated in the living animal by a wide, fleshy partition, have only a thin plate of bone between them. The upper incisors are broad; the canines long; and the lower incisors project forwards, somewhat as in the Lemurs. The arm-bone has a perforation (the ent-epicondylar foramen) on its inner side above the articulation of the elbow joint, to give passage and protection to an important artery and nerve. The thumb is very short; the claws are small and weak. The dorsal and lumbar vertebræ together number twenty-two, the greatest number possessed by any American monkey. As in Chrysothrix, the external surface of the cerebral hemispheres is smooth and almost devoid of convolutions, but their inner faces exhibit several of the more important grooves seen in the higher Apes.

All the species are arboreal and nocturnal, hiding away in the daytime and roaming during the night, giving vent to loud howls, or Cat-like cries, as they move in quest of the insects, small birds, and fruits, which form their food. They range from Nicaragua to the Amazon and Eastern Peru, and are called "Devil monkeys" by the Indians. They are very delicate, and soon die in captivity.

[ 168 ]


Aotus trivirgatus, Humboldt, Obs. Zool., p. 306, fig. 28 (1811).

Nyctipithecus trivirgatus, Gray, Ann. Nat. Hist., x., p. 256 (1842); id., Cat. Monkeys Brit. Mus., p. 58 (1870); Schl., Mus. Pays Bas, vii., p. 213 (1876).

Characters.—Fur short, grey and brown, with a silvery lustre; on the crown of the head three long black linear streaks, distinct from each other; frontal spot whitish; back greyish-brown with a dark dorsal band and a long chestnut patch; chest and lower surface of body rusty-red; throat, and inside of limbs, greyish-ashy; tail long, cylindrical, and with short, blackish-brown hair, more yellow on the under surface of the base. Length of the body, 12 inches; of the tail, 14 inches.

Distribution.—The type specimen was obtained by Humboldt on the banks of the Cassiquiare, near the head waters of the Rio Negro. Mr. Bates found it at Ega and at other places on the Upper Amazon region. It has been recorded also from Guiana; and from Chanchamayo in Peru, at 3,000 feet above the sea.

Habits.—The habits of the Three-banded Douroucoli are entirely nocturnal. They hide in small troops in a hole in the trunk of a tree from morning till twilight, hunting for food during the night. They have a singularly loud and far-reaching voice for such small animals.


Nyctipithecus lemurinus, Is. Geoffr., Arch. Mus., iv., p. 24, pl. 21 (1844); Gray, Cat. Monkeys Brit. Mus., p. 58 (1870).

[ 169 ]Nyctipithecus felinus, Gray, List Mamm. Brit. Mus., p. 14 (1843); Schl., Mus. Pays Bas, vii., 214 (1876).

Characters.—Fur of body and head long; tail depressed, broad, with the hair bushy and spreading on the sides as in a Squirrel. Head presenting a dark frontal area with a round white spot over each eye.

Distribution.—The Lemurine Douroucolis are found in Colombia and in Upper Amazonia; at Macas, on the eastern side of the Andes; and on the upper branches of the main streams of the Amazon, as far as a congenial habitat is met with.


Nyctipithecus rufipes, Sclater, P. Z. S., 1872, p. 3, pl. 1.

Nyctipithecus vociferans, Spix, Sim. et Vespert. Bras., p. 25, pl. 19 (1823; part); Schl., Mus. Pays Bas, vii., p. 214 (1876; part).

(Plate XV.)

Characters.—Above grey, slightly washed on the back with rufous; under side reddish fulvous; three vertical black stripes on the head, similar to N. trivirgatus, but much less distinct, narrower, and showing a prominent triangular white patch over each eye; ears large and prominent, almost nude (perhaps the result of captivity). Hands and feet rufous; tail short-haired, cylindrical; the basal half rufous, the remainder reddish-black. Length of the body, 11 inches; and of the tail, 16 inches. The absence of the long chestnut patch on the back distinguishes N. rufipes from N. trivirgatus, and its paler colour and the indistinctness of its head-stripes, separate it from N. felinus.

Distribution.—Nicaragua; San Juan del Norte.

[ 170 ]


Simia azaræ, Humb., Obs. Zool., p. 359 (1811).

Pithecia miriquouina, Geoffr., Ann. Mus., xix., p. 117 (1812); Kuhl, Beitr., p. 43 (1820).

Nyctipithecus azaræ, Schl., Mus. Pays Bas, vii., p. 212 (1876).

Characters.—A large rhomboidal black patch between the two large superciliary spots, the two acute angles of which are prolonged, the one under the base of the nose, the other in the median line to the top of the head; the inner side of the limbs, the under side of the body, throat, and chin of a reddish-ochre colour.

Distribution.—The right bank of the River Paraguay, in the north-east of the Argentine Republic, but not in Paraguay proper.


Nyctipithecus felinus, Spix, Sim. et Vespert. Bras., p. 24, pl. 18 (1823); Is. Geoffr., Cat. Méth. Primates, p. 39 (1851); Gray, Ann. N. H., x., p. 256 (1842).

Nyctipithecus oseryi, Is. Geoffr. et Deville, C. R., xxvii., 1848, p. 498 (juv.); Geoffr., Cat. Méth. Primates, p. 39 (1851).

Nyctipithecus commersonii, Gray, Cat. Monkeys Brit. Mus., p. 58 (1870).

Nyctipithecus vociferans, Schl., Mus. Pays Bas, vii., p. 214 (1876; part).

Characters.—Closely related to the last species, but differs in having the three facial streaks irregular and combining together on the crown, the middle one broad and lozenge-shaped; the frontal spots short, and white. Fur longer and more woolly; neck, chest, under surface of body, inner sides of the limbs, and the base of the tail yellowish; tail round.


Plate XV.


[ 171 ]Distribution.—This species is rather rare, but it has been obtained at Ega and at Tabatinga on the Upper Amazons; on the Ucayali, and near Yurimaguas on the Huallaga River—in the warm and humid virgin forests—in fact, generally along the Peruvian Amazons.

In speaking of his collections made at Ega on the Upper Amazons, which he describes as a fine field for a Natural History collector, Mr. Bates gives an interesting account of the Night-Apes, called "Ei-á" by the Indians, observed by him during his various journeys. "Of these I found two species (Nyctipithecus trivirgatus and N. felinus) closely related to each other, but nevertheless quite distinct, as both inhabit the same forests, namely, those of the higher and drier lands, without mingling with each other or inter-crossing. They sleep all day long in hollow trees, and come forth to prey on insects and eat fruits only in the night. One cannot help being struck by this curious modification of the American type of Monkeys, for the Owl-faced Night-Apes have evidently sprung from the same stock as the rest of the Cebidæ, as they do not differ much in all essential points from the Whaiapu-Sais (Callithrix) and the Sai-miris (Chrysothrix). They have nails of the ordinary form on all their fingers, and semi-opposable thumbs; but the molar teeth (contrary to what is usual in the Cebidæ) are studded with sharp points, showing that their nocturnal food is principally insects.

"I kept a pet animal of N. trivirgatus for many months, a young one having been given to me by an Indian compadre as a present from my newly-baptized godson. These Monkeys, although sleeping by day, are aroused by the least noise, so that, when a person passes by a tree in which a number of them are concealed, he is startled by the sudden apparition of [ 172 ]a group of little striped faces crowding a hole in a trunk. It was in this way that my compadre discovered the colony from which the one given to me was taken. I was obliged to keep my pet chained up; it, therefore, never became thoroughly familiar. I once saw, however, an individual of the other species (N. felinus) which was most amusingly tame. It was as lively and nimble as the Cebi, but not so mischievous, and far more confiding in its disposition, delighting to be caressed by all persons who came into the house. But its owner, the Municipal Judge of Ega, Dr. Carlos Mariana, had treated it for many weeks with the greatest kindness, allowing it to keep with him at night in his hammock, and to nestle in his bosom half the day as he lay reading. It was a great favourite with everyone, from the cleanliness of its habits and the prettiness of its features and ways. My own pet was kept in a box in which was placed a broad-mouthed glass jar; into this it would dive, head foremost, when anyone entered the room, turning round inside, and thrusting forth its inquisitive face an instant afterwards to stare at the intruder. It was very active at night, venting at frequent intervals a hoarse cry like the suppressed barking of a dog, and scampering about the room, to the length of its tether, after cockroaches and spiders. In climbing between the box and the wall it straddled the space, resting its hands on the palms and tips of the outstretched fingers with the knuckles bent at an acute angle, and thus mounted to the top with the greatest facility. Although seeming to prefer insects, it ate all kinds of fruit, but would not touch raw or cooked meat, and was very seldom thirsty. I was told by persons who had kept these Monkeys loose about the house, that they cleared the chambers of bats as well as insect vermin. When approached gently, my Ei-á allowed [ 173 ]itself to be caressed; but when handled roughly it always took alarm, biting severely, striking with its little hands, and making a hissing noise like a Cat.

"I have mentioned the near relationship of the Night-Apes to the Sai-miris (Chrysothrix), which are among the commonest of the ordinary Monkeys of the American forests. This near relationship is the more necessary to be borne in mind, as some Zoologists have drawn a comparison between them and the nocturnal Apes of the Lemur family, inhabiting Ceylon and Java, and it might be inferred that our American Ei-ás were related more closely to these Old World forms than they are to the rest of the New World Monkeys. The large nocturnal eyes and short ears of the Eastern Lemurs are simply resemblances of analogy, and merely show that a few species, belonging to utterly dissimilar families, have been made similar by being adapted to similar modes of life...."

  1. "Red-footed Night-Monkey," on plate.