4 fe THE ORIGIN OF AUSTRALIA 
are exclusively Australian, none passing beyond the limit® 
of the zoological region, nearly all of them confined to the 
continent itself and to Tasmania, and none reaching New 
Zealand. Not only are they thus strictly lmited, but 
not a single fossil mammal of any kind is found in any Aus- 
tralian deposit older than the Pliocene. No such anomaly 
as this is known elsewhere : yet it has been entirely over- 
looked, and the tacit, or expressed, belief has arisen that our 
Marsupial fauna, with its vast development of types, com- 
parable with almost the entire series of orders of the Placen- 
taila, have been gradually evolved from primitive types 
whose remains will be found in our older Tertiary or Second- 
ary rocks. There is not the slightest evidence in support 
of such a view: it is a pure assumption, diametrically op- 
posed to facts. 
60. So far as geology teaches us, and there is no other 
basis for a sound judgment, the Australian Mammaha 
(except the Cetacae and Phocidae) appeared on the Continent 
in late Tertiary times, developed into the peculiar Australian 
forms with great rapidity, rapidly culminated in gigantic 
forms, and began to wane as rapidly. 
61. It is generally overlooked that our Mammalian 
fauna contains a large number of placental species. Our 
veteran osteologist, Mr. De Vis, so far as I know, is the 
only zoologist who has insisted on this fact. Taking the 
whole Australian Region, and citing only the genera given 
by Wallace in his ‘‘ Geographical Distribution of Animals,” 
we find thirty-five genera, ranging from the Primates and 
including almost every existing order. The number of 
Australian genera is nineteen. The Australian Marsupials 
include thirteen genera of Polyprotodonts and twenty of 
Diprotodonts. There are no less than eighty-two species 
of placental land animals recorded in my friend Ogilby’s 
Australian list. This is no mean proportion. It is quite 
unfair to look upon Australia as devoid of the so-called 
higher forms of mammal. 
62. If we omit the Dugong and the Seals, as hardly 
land animals, and the Dingo, which was probably intro- 
duced by man (perhaps very early man), we find these 
placental mammals are confined to the two _ orders 
(Chiroptera and Rodentia), which are best fitted to cope with 
