HKB
mammalia is that of India, containing a great variety of peculiar forms, such as the sloth-bear (Prochilus), the musk-deer (Moscus), the nylghau, the gibbon or long-armed ape, and many others.
6thly. A portion of the islands of the Indian archipelago might, perhaps, be considered by some geologists as an appendage of the same province. In fact, we find in the large islands of Java, Sumatra, and Borneo, the same genera, for the most part, as on the continent of India, and some of the same species, e. g. the tapir (Tapirus Malayanus), the rhinoceros of Sumatra, and some others. Most of the species, however, are distinct, and each island has many, and even a few genera, peculiar to itself. Between eighty and ninety species are known to inhabit Java, and nearly the same number occur in Sumatra. Of these, more than half are common to the two islands. Borneo, which is much less explored, has yielded already upwards of sixty species, more than half of which are met with either in Java or Sumatra. Of the species inhabiting Sumatra and not found in Java, Borneo contains the greater portion. Upon the whole, if these three large islands were united, and a fusion of their respective indigenous mammalia should take place, they would present a fauna related to that of continental India, and comprising about as many species as we might expect from analogy to discover in an area of equal extent. The Philippine Islands are peopled with another assemblage of species generically related to the great Indian type.
7thly. But the islands of Celebes, Amboina, Timor, and New Guinea, constitute a different region of mammalia more allied to the Australian type, as having an intermixture of marsupial quadrupeds, yet showing an affinity also to the Indian in such forms as the deer (Cervus), the weasel (Viverra), the pig (Sus), the Macaque monkey (Cercopithecus), and others. As we proceed in a south-westerly direction, from Celebes to Amboina and thence to New Guinea, we find the Indian types diminishing in number, and the Australian (i. e. marsupial forms) increasing. Thus in New Guinea seven species of pouched quadrupeds have been detected, and among them two singular tree-kangaroos; yet only one species of the whole seven, viz. the flying opossum (Petauris ariel), is common to the Indian archipelago and the main land of Australia. The greater the zoological affinity, therefore, between the latter and the New Guinea fauna, although it seems in some way connected with geographical proximity, is not to be explained simply by the mutual migration of species from the one to the other.
8thly. When Australia was discovered, its land quadrupeds, belonging almost exclusively to the marsupial or pouched tribe, such as the kangaroos, wombats, flying opossums, kangaroo-rats, and others, some feeding on herbs and fruits, others carnivorous, were so novel in their structure and aspect, that they appeared to the naturalist almost as strange as if they were the inhabitants of some other planet. We learn from the recent investigations of Mr. Waterhouse,[875] that no less than 170 species of marsupial quadrupeds have now been determined, and of the whole number all but thirty-two are exclusively restricted to Australia. Of these thirty-two, nine belong to the islands in the Indian archipelago before mentioned, and the other twenty-three are all species of opossum inhabiting the tropical parts of South America, or a few of them extending into Mexico and California, and one, the Virginian opossum, into the United States.