Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/181

AFFINITIES.] APE 167 There are, however, certain islands which seem eminently well suited to support an apo population, where apes, nevertheless, are conspicuous by their absence. Such are the West Indian Islands, Madagascar, 1 and New Guinea ; moreover, no ape inhabits tropical Australia. These facts become the more remarkable, if, as Father David suspects, apes exist in Northern China to-day. Evidently it is not climate which prevents their existing in Central Europe now. The continents of Africa, south of the Sahara; of Asia, south of the Himalaya ; and of America, from Panama to the southern part of Brazil, are, with the islands before mentioned, the special ape regions of the existing fauna. There is a remarkable difference between the ape popu lation of the New and the Old World, the latter being inhabited exclusively by Simiadce, the former as exclusively by the Cebidce. Europe has but a single ape species ; and Asia, north of the Himalaya, has but the few found in Thibet, China, and Japan. Africa, north of the Sahara, is zoologically a part of Europe, and there also Macacus inuus is found, which is the only African species of the genus. African apes are the chimpanzee and gorilla of the west coast, the former extending eastwards to 28 E. long.; the Colobi (which are, in fact, but the African form of Semnopithecus), the long-tailed Cercopitheci, including mangabeys (or white-eyelid monkeys) ; and, lastly, the baboons, Cynocepliali. The genus Cynocephalus extends into Arabia ; but that, zoologically speaking, is a part of Africa. The Asiatic regions possess the orang (Simia) (in Borneo and Sumatra), the long-armed apes (Hylobates), the Scmnopitheci, and Macaci. One form of Macacus, and a very peculiar one (M. niger), is found in the islands Batchian and Celebes ; and it is a noteworthy fact that this, the most baboon-like of all the Macaci, should only exist in a region so extremely remote from Africa. The genus Macacus is the most widely spread of any existing genus namely, from Gibraltar, North Africa, Thibet, and Japan (perhaps even from Northern China), down to the island of Timor, and from the north-west of Africa in the west, to Batchian, Japan, and the Philippine Islands in the east. In ancient times this genus seems to have extended to France, and even to Essex. It is interesting to note that, in the Miocene period, the geographical range of the apes of India was much greater. Gibbon-like monkeys existed in the south of France, while forms intermediate between Sein- nopitheeua and Macacus abounded in Greece. In America, north of Panama, the genera as yet known to be represented are Chrysothrix, Nyctipithecus, Cebus, Ateles, Mycetes, and Hapale, in Veragua; Nyctipitliecus, Cebus, Ateles, and Mycetes, in Costa Rica and Nicaragua; Ateles and Mycetes, in Guatemala; and Ateles, in Southern Mexico. Brazil is, of course, the headquarters of the American apes ; but different portions of that vast region have a somewhat different ape fauna. Thus the genus Eriodes appears in South-Eastern Brazil to represent the species of Ateles inhabiting the more northern and western parts of the empire. Southwards, the genera Cebus, Mycetes, Chrysothrix, and Callithrix extend furthest ; but they do not probably all extend to the furthest limit yet known, namely, 30 S. The species found farthest south are Mycetes caraya, Cebus fatuellus, and Callithrix per sonal us. ZOOLOGICAL POSITION AND AFFINITIES OF APES. By universal consent apes are placed in the highest rank of all brutes, and, excepting man, are generally taken to 1 Madagascar is the special home of the half-apes or lemurs. be the most perfect animals of the mammalian class. It may be questioned, however, whether, if the animal man had never existed, this place would be assigned them by any observing intelligence. The half-apes, or lemurs, commonly placed in the same order with them, are cer tainly inferior mammals; and it might be contended that the perfection of the mammalian type is rather to be found in the Felidae (or cat family), by reasoning analogous to that by which it might also be contended that birds (with their differentiated limbs, perfect circulating and respira tory systems, acute sense organs, complex instincts, and teachableness) are really the highest of all vertebrate animals, and represent the vertebrate type of structure carried to the highest degree of perfection yet attained. The question as to which animals are most nearly allied to apes is one by no means easy to answer. Leaving man aside (whose close anatomical resemblance to apes is so obvious), it is at present extremely difficult to say what are the apes true zoological affinities. It is to be hoped that future palseontological researches may afford us materials for tracing these out; but at present a chasm separates the apes from every other group of animals. The half- apes, or lemurs, were generally considered to lead down from the apes towards the insectivora, and thence to the iniplacental mammals; but the differences between the apes and lemurs are so many and great, that it cannot be considered otherwise than in the highest degree improbable that (on the Evolution hypothesis) they took origin from any common root-form that was not equally the progenitor of other mammalian orders. But if the apes cannot be considered to show evidence of genetic affinity with any other mammalian order, do they constitute so homogeneous a group as to suggest the former existence of one ancient root-form common to them all 1 To this question it may be answered that the differ ences between the Simiadce and Cebidce are such as to render it doubtful whether they may not have had respectively quite different origins, and whether their resemblances may not have been superinduced by similarity of needs and conditions. The differences referred to are as to (1), dentition; (2), nasal septum; (3), tail the Cebidce showing a tendency to a curled tail-end, while the Simiadce never manifest any such tendency ; (4), cheek pouches ; (5), ischiatic callosities; (6), general form and habit of body; (7), opposability of the thumb; (8), bony meatus auditorius externus. All these characters, taken together, seem to make it probable that the Cebidce and Simiadce are not diverging offshots from some common ape parent, but that they have arisen in an independence as complete as that between the origin of either of them and the origin of the lemuroids or carnivores. Possibly further discoveries in the Miocene deposits of North America will reveal to us transitional forms between the Old and the New World apes, but the existence of such forms cannot certainly as yet be affirmed. It may be asked, however, Can the genera, which possess so many points in common as Cebus and Cercopithecus, have come to resemble each other inde pendently ] To this it may be replied, that the number of similarities of structure which must have had an inde pendent origin is so great that it is difficult to see why those of the two genera named may not also have had such an origin. As examples of such similarities of independent origin, the following structures may be referred to : Tho bony covering of the temporal fossa in Chelonia, Pelobates, and Lophiomys ; the compound tooth structure of Orycte- ropiis and Myliobatis; the coexistence of a certain form of dentition with a saltatory habit in Macropus and Macrosce lides; the presence of but eight carpal bones in Troglodytes and Tndri-s; the course of the vertebral artery in Auchenia

and Myrmecophaga ; the flying membrane in certain squirrels