CHAl’, XV11.1 
MAMMALIA. 
253 
The "Wombats are tail-less, terrestrial, burrowing animals, about 
the size of a badger, but feeding on roots and grass. They 
inhabit South Australia and Tasmania (Plate XI. vol. i. p. 439). 
An extinct wombat, as large as a tapir, has been found in the 
Australian Pliocene deposits. 
General Remarks on the Distribution of Marsupialia. 
We have here the most remarkable case, of an extensive and 
highly varied order being confined to one very limited area on 
the earth’s surface, the only exception being the opossums in 
America. It has been already shown that these are compara- 
tively recent immigrants, which have survived in that country 
long after they disappeared in Europe. As, however, no other 
form but that of the Bidelphyidse occurs there during the 
Tertiary period, we must suppose that it was at a far more 
remote epoch that the ancestral forms of all the other Marsupials 
entered Australia ; and the curious little mammals of the Oolite 
and Trias, offer valuable indications as to the time when this 
really took place. 
A notice of these extinct marsupials of the secondary period 
will be found at vol. i. p. 159. 
Order XIII. — MONO TREMA TA . 
Family 83.— OEXITHOKHYXCHIDyE. (1 Genus, 1 Species.) 
General Distribution. 
Neotropical 
SUB-REGIONS, 
N EARCTIC 
Sub-regions. 
PAL^E ARCTIC 
Sub-regions. 
Ethiopian 
Sub-regions. 
Oriental 
Sub-regions. 
Australian 
Sub-regions. 
— 
The Ornithorliyrwhus, or duck-billed Platypus, one of the most 
remarkable and isolated of existing mammalia, is found in East 
and South Australia, and Tasmania. 
