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THE AUSTRALIAN REGION (plate II., p. 50) Section I.—Boundaries Of The Australian Region
The Australian Region, as will be seen by the map (Plate II.), includes Australia, New Guinea, and the Moluccas, together with all the Pacific Islands and New Zealand. It is divided from the Oriental, the next adjacent region, by a line drawn between the two small islands of Bali and Lombok (called Wallace's Line), and passing thence through the Flores and Molucca Seas, between the islands of Celebes on the one side, and Sumbawa, Flores, Bouru, Sula, and Gilolo on the other. All the islands westwards of this line (i.e. Bali, Java, Sumatra, Borneo, Celebes, and the Philippines) are included in the Oriental Region; while all the islands to the eastwards, from Lombok to Timor, the Moluccas, and New Guinea, are referred to the Australian Region Besides this, the Australian Region includes all the islands of the Pacific, from the Pelews and Ladrones in the north-west, to the Sandwich Islands in the northeast, the Marquesas in the south-east, and New Zealand and its neighbouring islands in the south-west.
The boundaries, as above given, correspond with those laid down by Wallace in his work on Geographical Distribution, with the exception that the island of Celebes has been transferred to the Oriental Region.
Celebes, as Mr. Wallace has fully shown in his " Island Life" (14), is an anomalous island presenting a very difficult problem. It has doubtless relations to both the Oriental and the Australian Regions, but has besides many peculiar forms inhabiting it, which do not seem to connect it with either region. On the whole, however, the evidence of the mammals, at any rate, serves to connect it more closely with the Oriental Region, as will be seen by the discussion of the subject in the chapter dealing with that Region.
Section II.—General View Of The Mammal-fauna Of The Australian Region
The peculiarities of the Australian Region are very striking. Within its boundaries are found the only representatives of the lowest and most reptilian of the Orders of Mammals; these are the egg-laying forms, Ornithorhynchus, Echidna, and Proechidna, which constitute the order Monotremata (12).
Of the eight generally recognised families of Marsupials, or " Pouched Animals," no less than six are entirely confined to the Australian Region, with the exception of two species of phalanger (Phalanger v/rsinus and P. celebensis), which have crossed the boundary into Celebes. The seventh family, the Didelphyida}, or true Opossums, are found only in the Neotropical Region, whence they have intruded into the southern part of the Nearctic Region.
Of the other mammals, the Rodents and the Bats are the only orders at all adequately represented in the Australian Region. To the former belong six genera of Muridm (Mice), all of which, except the wide-ranging Mus, are confined to this Region; the only other Rodent that occurs in it is the Javan Porcupine, which has just crossed the dividing-line between the Oriental and Australian Regions into the islands of Flores and Sumbawa.
The Bats of the Australian Region (3) are very numerous, more especially in the islands to the north of Australia, where the tropical conditions are specially favourable to the development of this group. No less than twenty-eight genera, containing nearly one hundred species of Bats, are met with within the Region, and of these genera eight are not found elsewhere. This is a high percentage, only excelled in the Neotropical Region, which is extraordinarily rich in Bats, having no less than forty-two out of fortyseven genera confined to it.
The five other Orders of terrestrial mammals—the Ungulata, the Carnivora, the Insectivora, the Edentata, and the Quadrumana—may be considered as practically absent in the Australian Region, though members of several wide-ranging genera have just crossed the line of separation, and are represented in some of the islands on the north of Australia; but, with the exception of the Dingo, none of these reach the actual continent of Australia.
The question of the origin of the Dingo has not yet been settled. Although fossil remains of this animal have been found in the recent Tertiary deposits, it is difficult to say whether the Dingo was introduced into Australia by the aborigines or is indigenous. At the present time it appears to be found both in a wild state and in a semi-domesticated condition among the native Australians.
Section III.—Subdivision Of The Australian
The Australian Region may be most conveniently divided into five Sub-regions (see Plate II., p. 50); these are—
(1) The Austral Sub-region, containing—The islandcontinent of Australia, with the dependent island Tasmania.
(2) The Papuan Sub-region, containing—The islands lying to the north of Australia, including (a) the Timor group from Lombok to Timor-Laut; (£>) the Moluccas, of which the chief islands are Morty, Batchian, Gilolo, Bouru, and Ceram; (c) the large island of New Guinea; (d) the New Britain group, containing New Britain, New Ireland, the Admiralty Islands, and the Solomon group.
(3) The Maorian Sub-region, containing—The two islands of New Zealand, together with their outliers the Norfolk, Kermadec, and Chatham Islands, as also the Auckland, Campbell, and Macquarie Islands.
(4) The Polynesian Sub-region, containing—The various islands in the Pacific, from the Ladrones in the north-west to the Society and Marquesas in the south-east, of which the principal are New Caledonia, the New Hebrides, and the Fiji and Samoan groups.
(5) The Hawaiian Sub-region, containing—The Sandwich-Island group.
Of these, only the first two, the Austral and Papuan Sub-regions, need be considered in detail, as there are, practically speaking, no mammalian inhabitants, except Bats, in the other three Sub-regions.
Section IV.—The Austral Sub-region
The "island-continent" of Australia, as Mr. Wallace terms it, has, as has now been positively ascertained, a large portion of its interior so parched up and barren as to be almost destitute of animal life. But all along the east and south-east coasts, where there is land of sufficient elevation to condense the vapours from the adjoining ocean, more fertile districts are found. Besides the more widely diffused Australian types, some peculiar forms are met with only on this side of the continent. Tasmania, which is, in fact, but a recently separated piece of this portion of Australia, has also a moister and less extreme climate, and contains representatives of many of the special Australian forms, besides some indications of an autochthonous fauna.
The most peculiar mammals of Australia, and those which first claim our attention, are its representatives of the two forms which together constitute the Sub-class of Monotremes. These are the extraordinary genera Omithorhynchus and Echidna, which in their toothless jaws, in the conformation of their sternum and shoulder girdle, and especially in the structure of their reproductive organs, exhibit unmistakable signs of divergence towards the Classes of Reptiles and Amphibians. The first of these, usually known to the colonists as the " Duck-bill" or " Water-mole," (see Fig. 1, p. 23) is entirely aquatic in its habits, and is met with only in the streams and waterholes of New South Wales and Tasmania, where it burrows in the banks, and swims and dives with great facility. The Echidna, or "Spiny Ant-eater," is more widely distributed, and, as we