the facts at our command render it probable that it is so. The northern and eastern portions of the Celebes Sea have been ascertained to be from 2,000 to 2,600 fathoms deep, and such depths may extend over a considerable portion of it, or even be much exceeded in the centre. In the Molucca passage a single sounding on the Gilolo side gave 1,200 fathoms, and a large part of the Molucca and Banda Seas probably exceed 2,000 fathoms. The southern portion of the Straits of Macassar is full of coral reefs, and a shallow sea of less than 100 fathoms extends from Borneo to within about forty miles of the western promontory of Celebes; but farther north there is deep water close to the shore, and it seems probable that a deep channel extends quite through the straits, which have no doubt been much shallowed by the deposits from the great Bornean rivers as well as by those of Celebes itself. Southward again, the chain of volcanic islands from Bali to Timor appears to rise out of a deep ocean, the few soundings we possess showing depths of from 670 to 1,300 fathoms almost close to their northern shores. We seem justified, therefore, in concluding that Celebes is entirely surrounded by a deep sea, which has, however, become partially filled up by river deposits, by volcanic upheaval, or by coral reefs. Such shallows, where they exist, may therefore be due to antiquity and isolation, instead of being indications of a former union with any of the surrounding islands.
Zoological Character of the Islands around Celebes.—In order to have a clear conception of the peculiar character of the Celebesian fauna, we must take into account that of the surrounding countries from which we may suppose it to have received immigrants. These we may divide broadly into two groups, those on the west belonging to the Oriental region of our zoological geography, and those on the east belonging to the Australian region. Of the first group Borneo is a typical representative; and from its proximity and the extent of its opposing coasts it is the island which we should expect to show most resemblance to Celebes. We have already seen that the fauna of Borneo is essentially the same as that of Southern Asia, and that it is excessively rich in all the Malayan types of
mammalia and birds. Java and Bali closely resemble Borneo in general character, though somewhat less rich and with several peculiar forms; while the Philippine Islands, though very much poorer, and with a greater amount of speciality, yet exhibit essentially the same character. These islands, taken as a whole, may be described as having a fauna almost identical with that of Southern Asia; for no family of mammalia is found in the one which is absent from the other, and the same may be said, with very few and unimportant exceptions, of the birds; while hundreds of genera and of species are common to both.
In the islands east and south of Celebes—the Moluccas, New Guinea, and the Timor group from Lombok eastward—we find, on the other hand, the most wonderful contrast in the forms of life. Of twenty-seven families of terrestrial mammals found in the great Malay islands, all have disappeared but four, and of these it is doubtful whether two have not been introduced by man. We also find here four families of Marsupials, all totally unknown in the western islands. Even birds, though usually more widely spread, show a corresponding difference, about eleven Malayan families being quite unknown east of Celebes, where six new families make their appearance which are equally unknown to the westward.[[167]]
We have here a radical difference between two sets of islands not very far removed from each other, the one set belonging zoologically to Asia, the other to Australia. The Asiatic or Malayan group is found to be bounded strictly by the eastward limits of the great bank (for the most part less than fifty fathoms below the surface) which
stretches out from the Siamese and Malayan peninsula as far as Java, Sumatra, Borneo, and the Philippines. To the east another bank unites New Guinea and the Papuan Islands as far as Aru, Mysol, and Waigiou, with Australia; while the Moluccas and Timor groups are surrounded by much deeper water, which forms, in the Banda and Celebes Seas and perhaps in other parts of this area, great basins of enormous depths (2,000 to 3,000 fathoms or even more) enclosed by tracts under a thousand fathoms, which separate the basins from each other and from the adjacent Pacific and Indian Oceans (see map). This peculiar formation of the sea-bottom probably indicates that this area has been the seat of great local upheavals and subsidences; and it is quite in accordance with this view that we find the Moluccas, while closely agreeing with New Guinea in their forms of life, yet strikingly deficient in many important groups, and exhibiting an altogether poverty-stricken appearance as regards the higher animals. It is a suggestive fact that the Philippine Islands bear an exactly parallel relation to Borneo, being equally deficient in many of the higher groups; and here too, in the Sooloo Sea, we find a similar enclosed basin of great depth. Hence we may in both cases connect, on the one hand, the extensive area of land-surface and of adjacent shallow sea with a long period of stability and a consequent rich development of the forms of life; and, on the other hand, a highly broken land-surface with the adjacent seas of great but very unequal depths, with a period of disturbance, probably involving extensive submersions of the land, resulting in a scanty and fragmentary vertebrate fauna.
Zoology of Celebes.—The zoology of Celebes differs so remarkably from that of both the great divisions of the Archipelago above indicated, that it is very difficult to decide in which to place it. It possesses only about sixteen species of terrestrial mammalia, so that it is at once distinguished from Borneo and Java by its extreme poverty in this class. Of this small number four belong to the Moluccan and Australian fauna—there being two marsupials of the genus Cuscus, and two forest rats said to be allied to Australian types.
The remaining twelve species are, generally speaking, of Malayan or Asiatic types, but some of them are so peculiar that they have no near allies in any part of the world; while the rest are of the ordinary Malay type or even identical with Malayan species, and some of these may be recent introductions through human agency. These twelve species of Asiatic type will be now enumerated. They consist of five peculiar squirrels—a group unknown farther east; a peculiar species of wild pig; a deer so closely allied to the Cervus hippelaphus of Borneo that it may well have been introduced by man both here and in the Moluccas; a civet, Viverra tangalunga, common in all the Malay Islands, and also perhaps introduced; the curious Malayan tarsier (Tarsius spectrum) said to be only found in a small island off the coast;—and besides these, three remarkable animals, all of large size and all quite unlike anything found in the Malay Islands or even in Asia. These are a black and almost tailless baboon-like ape (Cynopithecus nigrescens); an antelopean buffalo (Anoa depressicornis), and the strange babirusa (Babirusa alfurus).
None of these three animals last mentioned has any close allies elsewhere, and their presence in Celebes may be considered the crucial fact which must give us the clue to the past history of the island. Let us then see what they teach us. The ape is apparently somewhat intermediate between the great baboons of Africa and the short-tailed macaques of Asia, but its cranium shows a nearer approach to the former group, in its flat projecting muzzle, large superciliary crests, and maxillary ridges. The anoa, though anatomically allied to the buffaloes, externally more resembles the bovine antelopes of Africa; while the babirusa is altogether unlike any other living member of the swine family, the canines of the upper jaws growing directly upwards like horns, forming a spiral curve over the eyes, instead of downwards, as in all other mammalia. An approach to this peculiarity is made by the African wart-hogs, in which the upper tusk grows out laterally and then curves up; but these animals are not otherwise closely allied to the babirusa.