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

by Henry O. Forbes

MAMMALS.

ORDER PRIMATES.

LEMURS, MONKEYS AND APES.

INTRODUCTION.

Of the varied forms of animal life that people the globe, those that possess a back-bone and two pairs of limbs (the Vertebrata) are considered the highest in the scale. Of the Vertebrata, those are held to be of superior organisation which possess warm red blood and suckle their young with milk from the breast (i.e., Mammalia). Our present volume deals with the highest and most specialised group of the Mammalia, and, therefore, of the whole Animal Kingdom.

Man, in respect of his mental endowments, stands alone and unapproachable among living creatures. Considered as to his "place in nature," however, he must be described as an erect-walking Mammal, possessing anterior extremities developed into hands of great perfection, for exclusive use as tactile and grasping organs, and posterior limbs, on which his body is perfectly balanced and entirely supported, exclusively devoted to locomotion, as well as highly specialised cerebral characters. These attributes in part constitute the standard by which we estimate superiority in animal structure, and fitness of adaptation.

Notwithstanding the numerous varieties and races of mankind distributed over every region of the globe, each exhibiting differences in habits, customs and superficial complexion, Man forms but one species, Homo sapiens, the sole representative of the unique genus of his family. Though the genus Homo is thus far apparently zoologically isolated, there is a remarkable group of animals, which we designate "Apes," and which, possessing many of the same structural characters more or less modified, stand apart from all the other Mammalia, and make a distinct approach to Man. Between Man, however, and the Apes, even the untrained eye at once perceives, amid obvious marks of inferiority, unmistakable resemblances, while anatomical investigations reveal that "the points in which Man differs from the Apes most nearly resembling him, are not of greater importance than those in which the Ape differs from other and universally acknowledged members of the group." (Flower and Lydekker.) The Apes, on the other hand, are so nearly related to the Monkeys, the Baboons and the Marmosets, by characters which insensibly merge into each other that they, along with Man, must logically be embraced in the same zoological division. The animals known to us as Lemurs, called by the Germans "Half-Apes" and by the French "False-Monkeys," are the nearest to the Apes and Man of all the remaining Mammals, though there are many points of divergence from the above-named groups. The Lemurs, in fact, exhibit considerable affinity to lower forms of Mammalia, especially to the Insectivora, but in internal structure and habit they approach the Anthropiform[^[1]] group just referred to—in the flattened form of the digits, the opposable great toe, with its ankle-bone (the ento-cuneiform) rounded for its articulation, as in the higher Apes and Man.

The Lemurs have, by many distinguished naturalists, been relegated to a distinct Order quite separate from the latter; but by such pre-eminent authorities as Linnæus, Lesson, Huxley, Broca and Flower, they have been assigned a subordinate position within that great Order, on which has been conferred the rank of the Primates of the Animal Kingdom.

The Order Primates, therefore, comprises two very homogeneous sub-orders—(1) The Lemur-like animals (Lemuroidea) including the Aye-Aye, the Tarsier, and the True Lemurs; and (2) the Man-like animals (the Anthropoidea), which embrace the Marmosets, the Baboons, the great Apes, and Man.

In common with all other Mammals, the Primates are furnished with an epidermal covering, which, except in Man, consists of a woolly or hairy fur. They possess four limbs and a tail, which may be long, short, or concealed, and which is often used as a prehensile organ. The young are born in a condition of greater or less helplessness, with their eyes, as a rule, unopened, and the framework of their bodies incompletely ossified, and consequently requiring protective care and entire nourishment from the mother, for a considerable period. At maturity this skeleton consists of a skull, a breast- and a back-bone of many pieces, ribs, jointed limbs, and a pair of collar-bones. As a knowledge of many of these bones and some of the more prominent organs of the body are necessary for an accurate comprehension of the description and classification of the animals discussed in this volume, a few of the more important must be briefly referred to.