Imágenes de páginas
PDF
EPUB

(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

REGION

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; (b) 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 Ornithorhynchus 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

shall presently see, has also representatives in the Papuan Sub-region. It inhabits the scrubs throughout the eastern districts of Australia, and is likewise occasionally found as far along the southern coast as Western Australia. In Tasmania a slightly different species (Echidna setosa) with

[graphic][subsumed][ocr errors][subsumed][merged small]

longer fur, almost concealing the spines (by some authors considered to be only a geographical race or sub-species of the typical form), is met with.

After the Monotremes, the most important group of mammals, and that which constitutes by far the most prevalent feature of Australian mammal-life, is the great

order of Marsupials. Although not absolutely restricted to Australia, since one of its component families is purely American, the Marsupials, from their prevalence, constitute a still more noticeable feature of the Australian fauna than the Monotremes. Of the seven families into which this order is usually divided by naturalists, six are entirely confined to the Australian Region. Moreover, the Marsupials are so abundant in Australia proper, as to quite overshadow the few representatives of the higher orders of mammals found within its limits.

The carnivorous Dasyures (Dasyuridæ) forming the first of these families take the place in Australia of the true carnivora of other parts of the world. They are seminocturnal in habits, and prowl about at dusk in search of the smaller mammals and birds which constitute their food. In Tasmania two peculiar forms of Dasyures occur, which are not met with in the Australian continent. These are the Thylacine, a dog-like animal with a long tapering tail, noticeable as being the largest of living carnivorous Marsupials (Fig. 2, p. 25), and in general external appearance so much resembling our familiar domestic friend that the uninitiated can hardly be persuaded that its proper place is in a different order of mammals; and the Sarcophilus ursinus, or Tasmanian Devil, as it is popularly called—a somewhat aberrant dasyure of a prevailing black colour, about the size and somewhat of the shape of an English badger, and remarkable for its savage and voracious disposition. Both these animals, now confined to the island of Tasmania, must have formerly extended into Australia, as their remains have been found fossil in the caves of the Wellington Valley of New South

« AnteriorContinuar »