﻿INTRODUCTION. 3 



Borneo, or its continuation which runs between Lombock on 

 the east, and Bah, at the extremity of Java, on the west, we 

 shall find all the islands lying to the westward of that line 

 devoid of Marsupials, and possessing a Mammalian fauna closely 

 akin to that of India. The line of the channel in question is, 

 therefore, evidently a very important one as regards distribu- 

 tional zoology ; and since this importance was first clearly 

 demonstrated and explained by the great explorer and natural- 

 ist. Dr. A. R. Wallace, it is now by common consent appro- 

 priately denominated " Wallace's line." To the eastward Marsu 

 pials extend as far as New Ireland and the Solomon Islands, 

 but they are unknown in Polynesia proper, as, indeed, they are 

 in New Zealand, where, by the way, save for a few Bats and 

 perhaps a Rat, there are no indigenous Mammals at all. 



Such is, roughly speaking, the general distribution of the 

 Marsupials of the Australian region. It must not, however, be 

 supposed that the group is confined to that part of the world, 

 although it there attains a much greater development than 

 elsewhere. As a matter of fact, a single family of Marsupials 

 — namely, the Opossums — is found throughout the wooded 

 districts of Central and South America, extending southwards 

 to the open pampa of Argentina, and represented in North 

 America by a single species which ranges as far north as the 

 Hudson river and Missouri. These Opossums, which, by the 

 way, must not be confounded with the so-called Opossums 

 (really Phalangers) of the Australian colonists, are all car- 

 nivorous, but differ widely in structure from the members of the 

 group inhabiting Australia. That they were originally Old 

 World forms is proved by the occurrence of their fossil remains 

 in the middle Tertiary deposits of England and other parts of 

 Europe, where Marsupials allied to those of Australia are now 

 unknown. If, however, we descend deeper in the geological 

 sca^e, and reach the lower portion of that great series of rocks 



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