(Plate XLI.)
Characters.—This species was first indicated by Du Chaillu on his return from his celebrated journey to the Gaboon, but based on poor skins, which left much doubt as to the species being distinct. Excellently preserved specimens were, however, brought home by Marche and Dr. Compiégne, and some of them passed into the Dublin Museum, but it was not till 1885, when a living specimen, now known to fame as "Sally," was received at the Zoological Gardens in London, and lived there for five years, that the correctness of Du Chaillu, as to the distinctness of his "Kooloo-kamba," A. calvus, from A. troglodytes, was proved and accepted.
Similar to A. troglodytes, but distinguished from it by the face, hands, and feet being quite black, or brownish-black, instead of pale flesh-colour; the front, top, and sides of the head and face are nearly naked, having only a few short hairs on the head, which is quite destitute of any signs of the parting so conspicuous in A. troglodytes. The hair is blacker than in the latter species, and extends only for a short distance in front of the level of the ears, and on the sides of the face; the temporal region and cheeks show a scanty growth; on the chin and upper lip a sparse crop of short hairs, chiefly white; long scattered black eyebrows, which do not meet in the mid-line, spring from the supra-orbital ridges. The ears are as large as in A. troglodytes, very flat, but stand out more prominently from the side of the head; their margin is nude, and there is no lobule. The hands are haired across the knuckles, and again (after a naked band) on the back of the hand and arm; the foot is haired down to the first joints of the toes; the nails and fingers are very human in appearance.
Face very prognathous; the nasal bones ridged in the mid-line; the foot less like a human hand than even in the Orang. "Sally's" brain weighed 83⁄5 ounces.
The expression of the face, the expanded nostrils, the thicker lips, especially the lower lip, and the more elevated skull, all distinguish A. calvus from A. troglodytes; in its muscular anatomy and in its brain it also shows points of difference.
Distribution.—The interior of Gaboon, in Western Africa.
Habits.—The Bald Chimpanzee showed in captivity a disposition to live on animal food, which the Common Chimpanzee never does. "Sally" had also the singular habit of producing pellets, resembling the castings thrown up by Raptorial birds; they were composed of feathers (of the birds she had eaten) and other indigestible substances taken with her food. Moreover, "Sally," as this Chimpanzee, now famous in the annals of zoology, was named, was an expert rat-catcher, and caught and killed many rats that entered her cage. "Her intelligence was far above that of the ordinary Chimpanzee. With but little trouble she could be taught to do many things that require the exercise of considerable thought and understanding." (Bartlett.) In general habits A. calvus differs, so far as known, in no respect from A. troglodytes.
It was on this Ape that the late Dr. G. J. Romanes, attracted by its high intelligence, made his interesting psychological experiments, which are related in the Proceedings of the Zoological Society for 1889. "Her intelligence was conspicuously displayed by the remarkable degree in which she was able to understand the meaning of spoken language—a degree fully equal to that presented by an infant a few months before emerging from infancy, and, therefore, higher than that which is presented by any brute, so far at least as I have met with any evidence to show. Having enlisted the intelligent co-operation of the keepers, I requested them to ask the Ape repeatedly for one straw, two straws, or three straws. These she was to pick up and hand out from among the litter of her cage. No constant order was to be observed in making these requests, but whenever she handed a number not asked for, her offer was to be refused, while if she gave the proper number her offer was to be accepted, and she was to receive a piece of fruit as payment. In this way the Ape was eventually taught to associate these three numbers with their names.... As soon as the animal understood what was required, and had learnt to associate these three numbers with their names, she never failed to give the number of straws asked for. Her education was then extended in a similar manner from three to four and four to five straws." "Sally" rarely made mistakes up to that number, but above five and up to ten, to which one of the keepers endeavoured to advance her education, the result is uncertain. "It is evident that she understands the words seven, eight, nine, and ten, to betoken numbers higher than those below them, and when she was asked for any of these numbers above six, she always gave some number over six and under ten. She sometimes doubled over a straw to make it present two ends, and was supposed to hasten, with the small stock of patience she possessed, the attainment of her task." Dr. Romanes was disposed to think that the uncertainty which attended her dealing with the numbers six and seven was due to her losing patience rather than to her losing count. It was at all events evident that "Sally" could count accurately up to five. Dr. Romanes tried to teach her colours in the same way, but the result was so uniformly negative that he was disposed to think that she was colour-blind, as she was taught to distinguish between white straws and the straws of any other colour, but she could not be taught to go further.
In 1875 a female Ape, which received the name of "Mafuca," was received from the Loango coast at the Dresden Zoological Gardens. "This," says Dr. Hartmann, "was a wild unmanageable creature, 120 cm. in height, reminding us in many respects of the Gorilla. The face was prognathous [more so than in A. troglodytes]; the ears were comparatively small, placed high on the skull, and projecting outwards; the supra-orbital arch was strongly developed, and the end of the nose was broad, and there were rolls of fat on the cheeks. The creature was, moreover, strongly built, and the region of the hips and the belly was contracted, while the hands and feet were large and powerful. The general physiognomical resemblance between Mafuca and a female Gorilla [whose dead body I had examined] was very great." It was suggested that the creature might be a cross between a Chimpanzee and a Gorilla, as the traveller Koppenfels had affirmed he had shot such cross-bred animals. It is still an undecided question to what species it belonged.
Of the four genera of the Simiidæ, "the Gibbons are obviously most remote from Man, and nearest to the Cynopithecini (Cercopithecidæ).