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CHAPTER V THE ORIENTAL REGION
(plate V., p. 152) Section I.—Boundaries Of The Oriental Region
The Oriental is the smallest of the six Regions into which the Earth has been divided for the study of zoological distribution. On the west it includes the great peninsula of India and its attendant island of Ceylon. Its boundary on this side is probably the Suliman range of hills, though the fauna of Western Sind and the Punjab, which lie between that range and the Indus, is intermediate in character between those of the Oriental and Palsearctic Regions. Beyond this range the boundary runs eastwards along the slopes of the Himalayas, at an elevation of from 9000 to 10,000 feet above the sea-level. Above this height Palsearctic forms are chiefly met with, below it Oriental forms mostly prevail. Eastwards of Sikkim the boundary between the Palsearctic and Oriental Regions cannot be laid down with certainty, owing to our little acquaintance with the eastern part of Tibet and the adjacent portion of China. What knowledge we have of the fauna of this Region is due almost entirely to the celebrated French missionary, Pere David, who made considerable researches in Moupin, a small mountainous territory, situated at the extreme western edge of the Tibetan plateau. Pere. David's collections have been mostly described by M. Milne-Edwards (1). An examination of the list of the mammals obtained by him in this district shows that the fauna has a character intermediate between those of the Oriental and Palsearctic Regions, besides containing a considerable proportion of peculiar forms. As, however, most of the Oriental genera extend even further north into the Chinese province of Kansu, and some even cross into Japan, countries which are otherwise well within the Palsearctic Region, it will be most convenient to draw the boundary of the Oriental Region to the south of Moupin. Beyond this point again our knowledge of the distribution of the mammals is very scanty, and though the northern part of China appears to be distinctly Palsearctic, and the southern Oriental in its affinity, there is, so far as we know, a considerable admixture of forms all over this part of Asia. Probably the most convenient boundary will be found to be that adopted by Wallace—the northern edge of the basin of the Yang-tze-Kiang. This is, no doubt, to a great extent an artificial boundary, but such a fault is unavoidable in the present instance, as there is here no natural frontier to separate the two regions. In addition to the south-eastern part of Asia, the Oriental Region includes within its boundaries all the large and important islands lying between that continent and the Australian Region. The principal of these are the Chinese islands of Formosa and Hainan, the large group of the Philippines, together with Sumatra, Java, Borneo, and the adjacent islands up to Wallace's Line. With the exception of Celebes, all these islands are truly continental in character—that is to say, are separated from the mainland by seas of less than 100 fathoms of depth. But Celebes is in some respects anomalous, and will be considered in greater detail below.
The boundary between the Australian and the Oriental Regions called Wallace's Line, as having been first pointed out by that distinguished naturalist, runs between the two small islands of Bali and Lombok. Bali is connected by shallow water, and also by its zoological relationships, with Java; while Lombok agrees in character with Timor and the other Australian islands further east. From Bali the boundary of the Oriental Region runs in a north-eastward direction, between Celebes on the one side and the Sula islands and Gilolo on the other.
Section II.—General View Of The Mammal-fauna Of The Oriental Region
The Oriental Region lies almost wholly within the tropics. The greater part of the country within its borders enjoys a bountiful rainfall, and is covered with luxuriant forests; the only portion which is less favoured being the north-western part of India and the strip of country along the northern shores of the Persian Gulf. In these districts there is very little rain, and desert conditions and a desert Fauna, somewhat resembling those of the African Sahara, prevail.
The Fauna of the Oriental Region presents, on the whole, a striking contrast to that of the Australian Region. The characteristic features of the latter are doubtless due to the long isolation to which it has obviously been subjected, whereas the Oriental Region as regards its characteristic forms is more nearly allied to the neighbouring Palsearctic Region, from which probably most of its inhabitants have been derived.