DRILL.
Nothing is known about the wild habits of the Black Baboon, but it appears to be a wood Ape, and it certainly has not the impudence or the bold aggravating courage of the African Baboon in confinement. They are frequently brought over to Europe, and may be watched in most zoological gardens. They are capital climbers, but they like to remain a great deal on the ground, sitting upright on their haunches in a very sedate manner. Associating very well with other Monkeys, they appear rather affectionate in disposition than otherwise, and may be seen looking very quiet and stately whilst some more agile companion rubs his face and lips against theirs, apparently to their gratification. The distinction between the Black Baboon and the African kinds is slight, and they all belong to the same genus,[71] and therefore must have had a common parent in remote times. But the black one lives far away in the Asiatic islands, surrounded by animals different from those which live in Africa, many of which, nevertheless, have a curious African look about them. Now, the geologist asserts that there are proofs of the former connection by land of the mainland of Asia, Hindostan, and Africa. The facts upon which this assertion is made will be stated in several consecutive chapters of this work, and indeed particular allusions to them from time to time will be inevitable. It is only necessary to mention here that the separation of the two great masses of land occurred about the time of the elevation of the Himalayas as a mountain chain, and they are about as old as the Alps of Europe. Hence the Baboons, found as they are in the separated districts, existed as a united genus before those vast changes. If the Black Baboon is a forest dweller—and there appears to be good reason to believe that this is the case—there is something more than simple conjecture in the suggestion that the whole of the Baboons once lived in forest lands.
BLACK BABOON.
The Cynomorpha, or Dog-shaped Quadrumana, include the genera Semnopithecus, Colobos, Macacus, and Cynocephalus, and their distinctions and some of their anatomical peculiarities have been noticed, and they may be summarised as follows:—As a group, the Cynomorpha are more fitted for running on all-fours than for any other method of progression, and their construction relates to that of such running animals as the Cats as well as to that of the Monkeys. Thus the arm-bone (humerus) is unlike that of the man-shaped Apes; it is bent so as to be slightly convex forwards, and the top where the round joint is—the head of the bone—look upwards and backwards, and not upwards and inwards as it does in the Gorilla. The forearm bones, longer than the arm-bone, are modified, and the most movable of them (the radius) is so much jointed to the arm-bone that the power of moving the lower part of the forearm upwards and downwards (of pronation and supination) is much diminished. There is the extra bone in the wrist, making nine, and one of the bones sticks out behind (pisiform), so as to form a kind of heel to the hand. The thumb is complete except in the Colobi, but it is short in proportion to the other fingers; and in some the third and fourth fingers are equal in length, thus departing from the Ape, whose third finger is always longest, resembling rather that of beasts of prey. The blade-bone differs much from that of the Anthropomorpha, being longer and narrower, and the portion above its spine, instead of being large, as it is in such ponderous climbers, is small. All these arrangements relate to the running on all-fours, the palms of the hands being applied to the ground. Moreover, in order that the hand should thus resemble a foot in its duties, some of its muscles simulate those of the foot and fore-leg. Thus a muscle which extends the metacarpal bone of the thumb (the bone between the wrist and the thumb under “the ball”), and keeps the thumb flat on the ground in running, and tends to pull it up, has a slip which is attached to the bone of the wrist, called trapezium, and which is at the wrist end of the metacarpal bone. It extends the wrist as well as the thumb. Now this is an arrangement seen in the foot, where a muscle extends the great toe’s metacarpal bone and the ankle bones also. In order to carry out this extension of the fingers, so as to prevent downward bending (or flexing), they have a complete double set of extensor muscles.
SKELETON OF THE MANDRILL. (From the Cyclopædia of Anatomy and Physiology.)
All the Cynomorpha have the lifting muscle of the blade-bone; and the muscle which pulls the elbow back and assists in climbing, both in the Gorilla and its fellows, is present (the slip from the back to the elbow, Dorso-epitrochlearis).
The nature of the spine and back-bone processes has been noticed in the Mandrill, but it is necessary to state that the hip-and haunch-bones are not closed in behind by a distinct sacrum, as is the case in the Anthropomorpha. The arrangement in the Cynomorpha closely resembles that of the great beasts of prey, but the haunch-bones are turned out slightly so as to form a seat. There is considerable variation in the number of the bones in the back and tail. With regard to the hinder limbs, the thigh-bone has a round ligament at its joint with the pelvis, and the shaft bends forwards, and when the animal is at rest on all-fours the thigh projects forwards and downwards, thus indicating the almost permanent position of this great bone in most runners on all-fours, the Elephant being a remarkable exception. The heel-bone is flat from side to side, and the toe-thumb, which reaches about half way up the first joint of the next toe, has considerable powers of motion, and can be struck out from the foot or be pulled in. The climbing muscle exists ([page 106]), as does also the peculiar stretching muscle of the little toe (abductor of the metacarpal bone). A transversus pedis, already noticed, exists. As the fore-limb assists greatly in locomotion, and much climbing is done by it, the “calf” is not much required for the hind limbs; and one of the muscles of it (the soleus) has a comparatively small surface of origin—from the fibula alone. The great muscle of the back of the thigh, which assists in the perfect erect posture and in the running also in man, is incomplete in the Cynomorpha. Its fibres reach from the haunch-bone to the small bone of the fore-leg in these last, but in man they arise also all down the back of the thigh, and enable the knee joint to be kept straight. All these Monkeys have a muscle on the sole of the foot called the plantaris, but it is not seen in animals lower in the scale than the Quadrumana; moreover, all the other muscles of the sole are more isolated than in man, and consequently they produce more distinct and separate movements of the toes, and especially in the toe-thumb. The tail, so variable in its development, consists of numerous bones, which are modified “back-bones,” or vertebræ, and in some there are little bones which are under these, and arranged in a rude V-shape, their office being to protect the blood-vessels which are enclosed by them. The muscles and nerves of this tail are special, and contribute to its different movements. The huge canine teeth and the cutting first pre-molars have been noticed, and it only remains to observe that the Cynomorpha have a first set of teeth (milk teeth) which fall out gradually, and are replaced by the permanent ones. The milk teeth consist of four incisors above and below, two pre-molars above and below, and four true molars above and below, making twenty teeth in all. All these animals, except the first two genera, have simple stomachs, but the liver has several fissures in it in the Baboons (as it has in the Gorilla), and but few in the Asiatic species (as in the Orangs)—facts of no small significance, for it is very probable that the Gorilla is one of the Baboon line, as the Orang is one of the genealogical tree of a Semnopithecus. The brain exhibits all the convolutions seen in the Anthropomorpha, but the very monkeyish external perpendicular one is well marked. The little brain is not uncovered by the brain proper, which is shortest in the Sacred Apes and longest in the Baboons.
The description of the Cynocephali ends that of the Monkeys of the Old World—The Catarrhini—and the whole of the group may be classified as follows:—