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Section VI.—The Malayan Sub-region
The Malayan Sub-region lies entirely within the tropics, and almost the whole of it is covered with a luxuriant tropical jungle. It is here, consequently, that we find the Oriental fauna in its highest state of development, and with the least admixture of forms belonging to other Regions. With the exception of the Malay Peninsula, the whole of this Sub-region consists of islands, which, however, are separated from the main continental mass by comparatively shallow water, so that an elevation of 100 fathoms would obliterate the whole of the sea between the various islands, leaving them connected with one another and with the Asiatic continent. There can be no doubt that these islands, all of which have very rich faunas, have been stocked from the mainland, and that a careful study and comparison of their component parts would go far to enable us to trace out the past history of the Region, and to find out what changes have taken place from time to time in the distribution of land and sea.
If a careful analysis of the mammalian genera of the Sub-region be made, it will be found that the greater number of the genera found on the mainland extend to all the three larger islands, Sumatra, Java, and Borneo, and that of the remaining genera the larger proportion are common to the Malay Peninsula, Sumatra, and Borneo, and are not found in Java. This would seem to indicate that Java was separated from the mainland before Sumatra and Borneo, and this view is further borne out by the fact that individual species of a genus are frequently common to the Malay Peninsula, Sumatra, and Borneo, whereas in Java they are replaced by slightly different forms. The Philippines, though connected with Borneo by two chains of islands, so that the straits separating the group from Borneo are nowhere very wide, contain a poor mammal-fauna as compared with Borneo. Only about fourteen genera, exclusive of bats, have reached these islands, and, with one exception, these are all widespread. But it must be recollected that the Mammal-fauna of the Philippines is still very imperfectly known.
The following table gives the figures relating to the distribution of the genera within the Sub-region (excluding bats):—
Number of genera that occur in—
(1) The Malay Peninsula, Sumatra, Borneo, and Java . 36
(2) The Malay Peninsula, Sumatra, and Borneo . . 6
(3) The Malay Peninsula and Borneo alone ... 3
(4) The Malay Peninsula, Sumatra, and Java... 2
(5) The Malay Peninsula and Java alone ... 1
As regards the Philippines, the total number of mammal genera (exclusive of bats) is fourteen, thirteen of which occur also in the Malay Peninsula and islands; one is confined to the Philippines alone; in addition five Malayan genera reach Palawan, a large island lying between Borneo and the Philippines.1
Although the Malayan Sub-region does not contain any endemic genera of Ungulates, there is one form the distribution of which is so remarkable that special attention must be drawn to it. This is the Tapir, one species of
1 This calculation was made before Mr. John Whitehead's great discoveries in the highlands of North Luzon (see Ann. N. H., ser. 6, vol. xvi., p. 160, and Tram. Zool. Soe., vol. xiv., pt. 6) were announced by Mr. Thomas. These embrace five new generic forms of rodents, and there are probably more to follow.
which is found in the Malay Peninsula, Sumatra, and Borneo, the only other Tapirs now existing in the world being met with in Central and Southern America. This is one of the most interesting cases known of what is termed "discontinuous" distribution, but the explanation of it is not very difficult. If we turn to the records of palseontology, we find undoubted remains of the members of the genus Tapirus recorded in the Miocene formation of France, in North America, and also in the Pliocene of China. There can be little doubt, therefore, that the Tapir, which is a harmless beast, destitute of all means of offence and defence, has been driven out of these northern countries into the tropical forests of South America and Malaya, where the absence of competition has enabled it to survive.
Among the Malayan Rodents we find the squirrels (Sciuridm) even more abundant than in the last Subregion. Two of the species belong to a separate genus (Rhithrosciwrus) which does not occur elsewhere. There are also two endemic genera of rats (Muridm) — one (Phlmomys) from the Philippines, the other (Pithechirus) from Sumatra and Java.
A genus of Porcupines (Trichys), which differs from Atherura in several important cranial characters, is confined to Borneo.
Three genera of Malayan Carnivores are worthy of special mention. One of these is Hemigale, not very far removed from the Palm-cats, with two species, a second one having been recently discovered by Mr. Hose in the mountains of Borneo. The second is Cynogale, also belonging to the same family. The latter, which is semiaquatic in its habits, and bears a superficial resemblance to an otter, is found in the Malay Peninsula, Borneo, and Sumatra. A third endemic Carnivore, Mydaus, which,
Fig. 28.—The Orang.
like the American Skunk, is remarkable for the very powerful odour emitted from its anal glands, was originally
described from the mountains of Java, but has since been obtained from Sumatra and Borneo.
Of the Insectivores by far the most important genus in the Malayan Sub-region is the Tree-shrew (Tupaia), of which at least a dozen species are here found. The Treeshrews are small animals, of the general appearance of squirrels, that live chiefly among the branches of trees, and, like the squirrels, sit on their haunches and use their fore limbs for holding their food. An allied genus, with an elegant double fringe of long hair to its tail (Ptilocercus), is confined to Sumatra and Borneo.
Tarsius, belonging to a distinct family of Lemurs, inhabits the forests of most of the islands of the Sub-region, as well as Celebes. It is a small animal, about the size of a squirrel, deriving its name from the fact that the tarsal bones of its foot are greatly elongated.
Among the Monkeys, in addition to the three genera found also in the Burmese Sub-region, we have the Proboscis Monkey (Nasalis) of Borneo, very remarkable for its large and projecting nasal organ. Finally, in Sumatra and Borneo we find the Orang (Simia), of which there are possibly two species, although this is by no means certain. These large man-like apes (see Fig. 28, p. 144), which form, along with the Gibbons, and the African Chimpanzee and Gorilla, the family Simiidm, inhabit mostly the low swampy districts near the coast; they may be distinguished at once from their African cousins by the reddish-brown colour of the long hair with which they are clothed. In some respects they are the most closely allied to Man in structure of the anthropoid Apes.
The following is a summary of the Malayan genera of mammals, constructed on the same plan as in the case of