176 THE BOOK OF THE ANIMAL KINGDOM 



of an animal closely allied to the carnivorous marsupials of Australia 

 have been discovered. It is all very wonderful. But "knowledge 

 grows from more to more," and naturalists who flourish in the next 

 century may find reason either to endorse or to modify or even to 

 discard the theories we students of to-day have faith in and have 

 built up with such care and labour. 



With the knowledge at present possessed, it seems improbable 

 that the primitive marsupials characteristic of Australia entered the 

 continent from the north ; they may have been cradled in Africa, and 

 from thence spread to the two great Southern lands. The higher 

 mammals were kept out of Australia by the Strait of Lombok — that 

 deep, narrow channel of the sea has been a barrier to southern 

 migration for a longer period of time than the mind can easily 

 think upon. 



In the introduction to his Marsupials and Monotremes, Mr. 

 Lydekker gives a lucid summary of the peculiarities of Australian 

 zoology. 



"Differing widely from all other regions of the globe," he writes, 

 "as regards both its fauna and flora, the great island continent of 

 Australia, together with certain of the south-eastern Austro-Malayan 

 islands, is especially characterized by being the home of the great 

 majority of that group of lowly mammals commonly designated 

 marsupials or pouched animals. Indeed, with the exception of the 

 few species of the still more remarkable monotremes, or egg-laying 

 mammals, nearly the whole of the mammalian fauna of Australia 

 consists of these marsupials, the only other indigenous mammals 

 being certain Rodents and Bats, together with the native Dog, or 

 Dingo, which may or may not have been introduced by man. All 

 the other orders, such as the Ungulates, or Hoofed Mammals, the 

 Apes and Lemurs, and the Carnivores are conspicuous by their 

 absence from the Australian landscape, where their respective places 

 are taken by the numerous representatives of the marsupial order, 

 which have adapted themselves to all modes of life. We have, for 

 instance, both terrestrial and arboreal types, while one form recently 

 discovered passes an underground existence like the Mole. Some 

 again are carnivorous and others herbivorous ; while among the 

 former certain kinds live on flesh and others on insects; an equal 

 diversity obtaining among the vegetable feeders." 



Australia has been isolated for countless ages, and its mammals 

 have developed along their own lines. In this region survive the 



