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the other Sub-regions. It will be seen that, while the total number of genera has not increased very much, the number of endemic genera is nearly doubled, as compared with those of the other two Sub-regions.
As already mentioned, the island of Celebes presents a problem of considerable interest to the student of geographical distribution. Celebes is separated from the other islands, both to the eastward and to the westward, by seas of considerable depth. Compared with the other Malayan islands, its fauna is scanty. This fact, and the very peculiar shape of the island, suggest a possibility of its having been formerly of greater extent, and of having been subsequently reduced by subsidence.
We will first review the mammal-fauna, and then try and deduce, from a study of it, our conclusions as to its past history.
In Celebes alone of the Oriental Region we find representatives of the marsupials characteristic of the Australian Region. These consist of two species of Phalanger, which differ from those of the Australian islands only in slight particulars.
The next interesting animal of this fauna is the Babirussa, a wild pig remarkable for the enormous size of its upper and lower canine teeth, which form, as it were, two pairs of horns on the upper side of the head. Another peculiar Ungulate, now generally referred to the widespread genus Bos, is the Anoa, which shows many primitive characters, and is entirely confined to the island.
The Mice and Squirrels of Celebes are fairly numerous, and most of the species are peculiar to the island; one rat forms a special genus.
Carnivores are very scarce in Celebes ; Insectivores have not been recorded at all. The Bats, which are numerous, comprise a considerable number of Australian forms, and one peculiar genus.
Among the Primates, Tarsius of the other Malayan islands is also found in this Sub-region, and one Monkey, Macacus maurus, seems to be restricted to it. Finally, one of the most remarkable of the animals of the island is the Black Ape of Celebes, belonging to a genus (Cynopithecus) intermediate between the Macaques and the Baboons. Cynopithecus appears to have found its way from Celebes into the adjoining island of Batchian, which belongs to the Australian Region.
The following table shows the mammals of this Subregion arranged in a form like those of the other Sub-regions :
From this summary it will be seen that the total number of Mammal-genera that occur in Celebes is thirtyone, the greater number of which (twenty in all) are placed under the headings of Palæogean and Cosmopolitan. These are all widespread genera, which do not afford us any particular clue to the origin of the Celebesian fauna. Nine out of the twenty are genera of Bats, which, as has before been remarked, are by nature much less restricted in their range than the true quadrupedal mammals. Of the remaining eleven only two (Mus and Sus) have any extensive distribution in the Australian Region; the others, although they have, in one or two cases, managed to struggle into adjoining islands belonging to the Australian Region, can in no sense be viewed as Australian genera.
Of the genera registered in the table as “Australian,” two are Bats, which have apparently reached Celebes from the more easterly islands of the Australian Region, where they have a wide distribution; the other is the genus Phalanger, which has been already alluded to as being the only member of the Marsupial Order found in the Oriental Region.
The endemic genera of Celebes are four in number, and judging from their affinities, it is impossible to believe that they have any relation to the animals now living in the Australian Region. Everything points to their being remains of a very ancient fauna, which must have been originally derived from the Asiatic continent.
The presence of the three Australian genera in Celebes does not in any way require the supposition of an ancient land-connection with that Region. This is obviously so in the case of the Bats, and the Phalanger is a strictly arboreal animal, and might easily have been drifted across a narrow strait on floating timber. On the other hand, to account for the greater proportion of Oriental forms found in the island, we are driven to the conclusion that at some time or other there has been some sort of land-connection between Celebes and the mainland of Asia. These are the principal reasons for transferring the island of Celebes from the Australian to the Oriental Region.'
SECTION VIII.-THE PAST HISTORY OF THE ORIENTAL
Considerable controversy has arisen from time to time with regard to the similarities that undoubtedly exist between the faunas of the Oriental and Ethiopian Regions. Some writers have urged that, in order to account for this, some form of direct land-connection must have existed at one time or another across the Indian Ocean between Southern India and South Africa. Others have maintained that the points of similarity between the two faunas have been exaggerated, and that no such land-connection is required to account for the facts, which can easily be explained on the supposition of a southward emigration of northern forms due to glacial cold.
1 For the most recent information on the mammals of Celebes see Meyer, “Säugethiere von Celebes und Philippinen-Archipelago," Abh. Mus. Dresden, vi., No. 6.
If we go back to the early part of the secondary epoch of geological time, we find, very well developed in India, a geological system known as the Gondwana, composed of sandstones and shales, which appear to be of fluviatile origin. These beds have long afforded a problem to geologists, as they cannot be at all satisfactorily correlated with any formations in Europe. In South Africa, however, we find a series of beds, also doubtless of fresh-water origin, known as the Karroo formation, which contains a nearly similar set of fossil remains, and in New South Wales, again, there are formations also agreeing in the characters of their fossils with the Gondwana beds. These facts, according to Mr. Oldham (3), our latest authority on this subject, are “inexplicable, unless there has been a continuous land-communication along which plants could freely migrate, and the conclusion is vastly strengthened when we remember that throughout the great part, if not the whole, of this period, a very different type of flora was flourishing in Europe and North America."
This land-connection may be of use in explaining the distribution of some of the lower vertebrates, but is of no assistance so far as the Mammals are concerned ; because in those early times it is probable that none of the families or even orders of our present Mammals had arisen. The best-known and richest of the mammal-bearing formations of India are certain beds in Sind, and the