A Hand-book to the Primates, Volume 1 (of 2)

by Henry O. Forbes

"The range of the Marmosets and Oustitis (Hapalidæ) is nearly co-extensive with that of the Monkeys proper." (Heilbrin.) The Pigmy and the Silky Marmoset range as far north as Mexico.

THE MARMOSETS AND TAMARINS. FAMILY HAPALIDÆ.

Of the New World, or Platyrrhine, Apes, the Marmosets come to be described first, as they have many characters which mark them out as the lowest of the Anthropoidea, and rank them nearer to the Lemuroidea than any of the others. They are specially characterised by having only thirty-two teeth, their dental formula being I22, C11, P33, M22. In the actual number of their teeth they agree with their Eastern relations, but with this difference, that in the latter the pre-molars are two, and the molars three, above and below on each side. Their flattened nose, with its wide partition between the nostrils, and their non-prehensile bushy tails, are also distinguishing characters. The face is nude, the ears large and sometimes fringed. Their hind-limbs are proportionately larger and longer than their fore-limbs, while the nails of their fingers and toes are not flattened as in the Old World Apes, but all form sharp curved claws, except on the much shortened great toe. The thumb is elongated and lies parallel, but quite unopposable to, nor indeed is it separable at will from, the rest of the digits. The fore-foot, consequently, "is a mere paw, and the term 'hand' is not applicable to it."... The plantar surface of the hind-foot "is very long, and the digits are very short. It follows from these facts that the term 'quadrumanous' is not applicable in any sense to the Marmosets." (Huxley.) These animals have no callosities over the ischial (or buttock) bones, and no cheek-pouches. In their smooth and rounded skull superciliary ridges are conspicuously absent; and the ear-capsules have, as has been already observed, no external bony canal for conducting sound vibrations to the inner ear. The hyoid bone resembles that of the Lemurs.

This family has been divided into two genera, distinguished from each other only by a variation in the relative length of their incisor and canine teeth, which is so slight as to render it doubtful whether these differences really warrant the generic separation of the two groups. As, however, the distinction has been maintained by nearly all writers upon these animals, the arrangement has been followed here, and the various species of the family will be described as true Marmosets (Hapale) and Tamarins (Midas). They are most numerous in the equatorial forests of South America.

THE MARMOSETS. GENUS HAPALE.

Hapale, Illiger, Prodr. Syst. Mamm., p. 71 (1811).

The members of this genus, which are often kept in captivity as pets, are very small animals, covered with thick and silky fur, and having bushy tails, equal to or even exceeding the length of their body. The head is round, the eyes large and watchful, the face short and nude, and often abundantly whiskered. The mouth is large; the ears also large and often fringed, and the neck sometimes clothed, with long hair. They are distinguished from the Tamarins (Midas) by having their upper incisor teeth long, narrow, and protruding outwards and forwards; the incisors of the lower jaw are also very long, and its canines small and shorter than the incisors, both being protrusive, as among the Lemurs. The cranial region of the smooth skull is conspicuously large in comparison with its facial portion, but the cerebrum shows a low type of organisation, and indicates a small degree of intelligence in its possessor; it is smooth and almost devoid of convolutions; the cerebrum, too, unlike that of the Lemuroidea, completely covers the cerebellum. The orbits are large, and almost completely walled in from the temporal depression behind. The stomach in form resembles that found in the higher groups, but its orifices for the entrance and exit of food are nearer to each other than in any of the other American Monkeys.

The female produces two or three young at a birth, instead of one, as is the general rule among the Anthropoidea. The species vary much in coloration, and some of them resemble the Lemurs in being ring-tailed.

The Marmosets are all gentle and playful in disposition, and are, on this account, very largely brought to Europe as pets; but they are very delicate, and rarely survive long in confinement after the advent of the Northern winter. They are arboreal, living in troops, and feeding on insects and fruit, and not disdaining flesh, especially of fishes, when they can obtain it. They emit a characteristic chirping noise.

I. THE COMMON MARMOSET. HAPALE JACCHUS.