EXTINCT FORMS. , 249 
PART ff. 
EXTINCT MARSUPIALS AND MONOTREMES. 
INTRODUCTORY. 
In addition to remains belonging to existing species, the 
superficial deposits and caverns of Australia have yielded evi- 
dence of the existence of a number of Marsupials belonging to 
species, genera, or even families entirely distinct from all their 
living allies, and in many cases attaining dimensions far ex- 
ceeding any of those of the latter. All these extinct Marsu- 
pials belong, however, to the same general groups as those now 
inhabiting Australia ; and they for the most part appear to have 
existed during the Pleistocene, or latest geological period, that 
Is to say, to the time when the Mammoth and Woolly Rhi- 
noceros flourished in Europe. 
In South America we have likewise evidence that during the 
same period species of Opossum were abundant, at least a large 
number of which were identical with those still, inhabiting the 
Same country. When, however, we examine the older Tertiary 
strata of Patagonia we find remains of extinct Marsupials which 
appear, so far as the present evidence may be credited, to be 
eae 
