122 ` Mr. Odilnv on certain Australian Quadrupeds, 
from the contiguous islands of Tasmania and New Zealand*, inhabited by 
races of human beings differing in language and origin from the natives of 
Continental Australia, appears almost to demonstrate his introduction from 
the north, where he is found in New Guinea, in Timor, in many of the smaller 
groups scattered throughout the Pacific Ocean, and in all the great islands of 
the Indian Archipelago. The extirpation of the Thylacinus Harrisii’ and 
Dasyurus Ursinus from the continental portion of Australia, is a strong cor- 
roboration of this supposition. It is contrary to all the principles of Zoolo- 
gical philosophy, and to what we already know of the laws which regulate the 
geographical distribution of animals, to suppose that these species, two of the 
largest Mammals in that part of the world, should have been originally con- 
fined to so small an island as Tasmania, to the exclusion of the neighbouring 
continent. The more probable theory is, that they were extirpated from the 
latter locality by the introduction of some more powerful adversary: this 
could have been no other than the native dog, to whose attacks these two 
species were more peculiarly exposed, from being the slowest, most cowardly, 
and least protected animals in the country. The Wombat, the Echidna, and 
the Ornithorhynchus are indeed more sluggish, but they are less obnoxious to 
attack on account of their burrowing and aquatic habits; the common Dasy- 
ures, Kolas, and Phalangers find security in their powers of climbing trees ; 
and the Kangaroos and Potoroos in speed of foot, or by concealing themselves 
in clumps of impenetrable brushwood. The Thylacine and Ursine Dasyure 
are in reality the only aboriginal inhabitants universally exposed to the attacks 
of the dog ; and their total extirpation from the continental portion of Australia, 
where he has been long established, and their confinement to the compara- 
tively small island of Tasmania, to which he had never found his way before 
the colonization of the country, all but demonstrate the recentness of his intro- 
duction into the neighbouring continent, But I shall not insist further upon 
this question, though its bearings upon the history of the origin and migra- 
tions of the aborigines of Australia are by no means devoid of importance: my 
object is to describe two of the indigenous Rodents of that singular continent ; 
* The dog is at present found in New Zealand, but is believed to have been introduced by the early 
navigators: in Van Diemen's Land he was absolutely unknown previously to the settlement of the 
British colonists at Hobart's Town. 
