OF MAMMALIA. 597 
assume much the same history of events as above to have 
occurred in the secondary strata of Europe, America and 
Africa, and possibly in the Eocene of America. ‘The 
Monotremata have, however, had to compete with the 
Metatheria even in Notogcea and have only survived in 
small numbers. 
It is well to note that the regions of Notogcea form more 
or less of a gradation. (1) Polynesia has practically an 
oceanic fauna and there are no mammals but bats. (2) 
New Zealand is equally bare of mammals but has more 
reptiles and birds. (3) Australia has Prototheria and 
Metatheria with a few incidental Eutheria. (4) Austro- 
Malaysia has more Lutheria, ¢.g., the pig, and approximates 
to Eurasia in faunistic character. The best line of separa- 
tion between Notogcea and the rest of the world would 
pass to the east of Celebes, but the demarcation is merely 
arbitrary. The chief point about the mammalian fauna of 
Notogcea is that it essentially belongs to the two lowest sub- 
classes to the almost entire exclusion of the third. The 
assumption in explanation is that Notogoea has been isolated 
from the rest of the world before the evolution and spread 
of the last sub-class, but not before the two lowest sub- 
classes had spread downwards from the north. 
Extant Mammalia of Notogeea. 
SUB-CLASS, ORDER, FAMILIES, 
Prototheria Monotremata 2 (Duckmoles, Echidne.) 
Metatheria Diprotodontia 3 (Kangaroos, wombats, 
phalangers. ) 
Poly protodontia 3 1c (Dasyurus, bandicoots, 
; marsupial-moles. ) 
Eutheria Rodentia I 7 Species. 
Carnivora rr 
Ungulata IT 
Chiroptera s Large number. 
2. Nroca@a.—This realm contains the remainder of the 
sub-class Ae¢atheria, not found in Wotogwa. These are the 
opossum-rats and the opossums, representatives respectively 
of the orders Dzprotodontia and FPolyprotodontia. Of the 
Eutheria there is no lack in point of numbers. It has a 
monopoly of one sub-order, the Xezarthra, or sloths, anteaters, 
