The Classification of the Monkeys of the New World—The Geographical Distribution of the Genera—The Fossil Monkeys of the New and Old World and their Alliances—The Former Old Fauna of Europe, Asia, and Africa—The Resemblance of Quadrumana to other Animals and Man
WITH regard to the Monkeys of the New World, they are to be grouped and classified as follows:—The Howlers must be placed by themselves, then the Spider Monkeys; the Lagothrix and the Sajous form a very distinct group; and thus the prehensile-tailed series is complete. Then come the non-prehensile-tailed. The Sakis form one group, and the Squirrel Monkeys, and the Night, or Owl Monkeys (the Douroucoulis), make a second. The Arctopithecini are another family, and consist of the Marmosets and Tamarins.
Family. | Sub-Family. | Genus. | Example. | |
| Platyrhini, or Cebidæ | Prehensile-tailed |  | Mycetes | Howler. |
| Ateles | Spider Monkey. | |||
| Lagothrix | Barrigudo. | |||
| Cebus | Cai. | |||
| Non-prehensile-tailed |  | Pithecia, including Brachyurus | Saki. | |
| Callithrix | Squirrel Monkey. | |||
| Nyctipithecus | Douroucouli. | |||
| Arctopithecini | Hapale | Marmosets. | ||
| Midas | Tamarins. |
The American Monkeys present some remarkable instances of the localisation and dispersion of species; allied kinds of different species, but with the same habits, occupying neighbouring districts, or being rather remote. And it is noticed that the great rivers form barriers between the homes of different kinds, which, however, mingle at the river source, and in the country not rendered impassable to them by broad streams. Thus Wallace noticed that the Howler (Mycetes Beelzebub) is apparently confined to the Lower Amazon, in the vicinity of Para, and a black species to the Upper Amazon, the Red Ursine Howler having the Rio Negro and the Upper Amazon as its forest ground.
One Spider Monkey is found only in the Guiana district north of the Amazons, and another, the Ateles ater, inhabits West Brazil, but the species of the genus range, as a whole, over the forest regions from the south of Mexico to 30° south latitude, and even on the west of the Andes.
The Lagothrix Monkeys, with their fine, furry coats, are found in the Ecuador district of the Amazons, but are unknown in Guiana and Eastern Brazil, and the species of the short-tailed Sakis are restricted to special districts; thus the Couxio is from Guiana, and does not pass the Rio Negro on the west, or the Amazon on the south. The white-skinned one is found on the Rio Negro, and the B. rubicundus on the Upper Amazon, another species being found on the lower part of the same river. So it is with the other Sakis with long tails. The genus is found widely dispersed, but the species are restricted in their roaming. One is found, according to Wallace, on the north bank of the Upper Amazon, and another, with a red beard, only to the south-west of the Rio Negro. The genus Cebus has a very wide range in South America, so has the Squirrel Monkey group, for they are found on both banks of the Amazon and Rio Negro; but the white-collared species is found only on the Upper Rio Negro, and another on the Upper Amazon.
The same author noticed the range of the Douroucoulis in the Amazon districts; one (N. trivirgatus) is found in Ecuador, and the Cat-like kind on the Upper Amazon. Equally restricted to limited districts were three kinds of Marmosets.
Fossil remains of Monkeys have been found in the New World in the Brazils, which belong to the existing genera Cebus, Callithrix, and Hapale. The fossil Cebus is at least four feet in height, and the Callithrix was of a very large kind. The fossil Ouistitis are large and small. The geological age of the Brazilian fossils is probably about that of the last European deposits. Now, the remarkable part of this interesting story is, that in the olden time there was the same division of the Monkeys into those of the Old and of the New World. The Catarhini were then, as now, restricted to Europe, Asia, and doubtless to Africa; and the Platyrhini were only found in America, and moreover the resemblance of the old forms to the new is remarkable, the large size of the fossils being in keeping with what is known about the large dimensions of most of the old forms of life. Rütimeyer’s discovery in Switzerland of a fossil with bones like those of the Howler (Mycetes), and yet like a Lemur in structure, and of vast antiquity, carries us back to a time when a different distribution of animals prevailed. Then there were American-looking and Madagascar-looking things in Europe, and associated with them were Opossums and other creatures foreign enough to it at the present time. Nevertheless, this fact gives the hint of the origin of the American Monkeys from the Lemurs. Lately the fossil remains of a Lemur-like animal have been found in North America. In concluding this short notice of the extinct Monkeys, it must be remembered that in the days when there were those agreeable northern climates which made Greenland a land of flowers, Indian Monkeys lived in the dense woods of Greece, Central Europe, and Southern France.
Mr. Darwin, who has collected a vast array of facts relating to the resemblance of the Monkeys to other beings, writes very much as follows:—
“The resemblance of Monkeys to man is greatly caused by the relative position of the features of the face. The eyes are arched over; they are separated by a long nose, the end of which in some is very human. The mouth is not carried back, but occupies the same general position as in man, and the forehead, so often wrinkled, is usually prominent, and like that of a child. The likeness is increased by the fact that anger, sorrow, pleasure, and satisfaction are displayed by the Monkey by nearly similar movements of the muscles and skin, chiefly above the eyebrows, and round the mouth. Some few expressions,” writes Mr. Darwin, “are, indeed, almost the same, as in the weeping of certain kinds of Monkeys, and in the laughing noise made by others, during which the corners of the mouth are drawn backwards, and the eyelids wrinkled. In man the nose is much more prominent than in most Monkeys; but,” writes the same author, “we may trace the commencement of an aquiline curvature in the nose of the Hoolock Gibbon, and this in the great-nosed Monkey is carried to a ridiculous extreme.” All this is disappointing to those who pride themselves on “the family nose,” especially if it is a Roman. Again, the faces of many Monkeys are furnished with beards, whiskers, and moustaches. The hair grows to a great length in some species of Semnopithecus, and in the Bonnet Monkey (Macacus radiatus) it radiates from a point on the crown, with a parting down the middle. This is a human fashion; moreover, in this Monkey the front hair ends rather abruptly, and a downy and almost smooth-looking forehead is shown. They have eyebrows in some instances. Mr. Darwin, in carrying out his investigations into the resemblances between men and Monkeys, said he is, as, indeed, have been all anatomists, very interested regarding the hair of the limbs of those he places in comparison. “It is well known,” he writes, “that the hair on our arms tends to converge from above and below to a point at the elbow. This curious arrangement, so unlike that in most of the lower Mammals, is common to the Gorilla, Chimpanzee, Orang, some species of Hylobates, and even to some American Monkeys. It is not invariable in the same genus, for in Hylobates agilis the hair on the forearm is directed downwards, or towards the wrist, in the ordinary manner, and in Hylobates lar, it is nearly erect, with only a slight forward inclination. It can,” he adds, “hardly be doubted that with most Mammals the thickness of the hair and its direction on the back are adapted to throw off rain, and even the transverse hairs of the Dog’s leg may serve for this end when he is curled up asleep.”