THE LIFE OF MAMMALS 
mals save a few bats and mice blown or drifted thither from 
the North; for the dingo, finally to prove so severe an enemy, 
was doubtless a late immigrant. In this complete freedom, 
and under favorable conditions, the marsupials soon became 
sufficiently diversified within their type to take advantage of 
all their opportunities, as in the more spacious outside 
world the more numerous other groups of mammals have been 
separated and fitted for a still wider variety of modes of life. 
AUSTRALIAN BEAVER-RAT, 
“We have, for instance,” remarks the latest monographer of the order, 
“both terrestrial and arboreal types, while one form recently discovered 
passes an underground existence like the mole. Some, again, are carnivo- 
rous and others herbivorous; while among the former certain kinds live 
on flesh and others on insects, an equal diversity obtaining among the vege- 
table feeders, some of which live on roots, others on grasses or leaves, others 
on fruits, and yet others on honey or the juices of flowers... It is, how- 
ever, very remarkable that not a single Australian representative of the 
order is aquatic in its habits, so that such an animal as a ‘marsupial 
otter’ does not exist in that region. The place in nature thus left 
vacant by the marsupials has been seized upon by the duckbill, and 
by two members of the rodent order (otherwise so poorly represented 
in Australia), of which the best known is commonly termed the 
‘beaver-rat.’” 
A valuable discussion of the Origin and Evolution of Marsupials, by 
B. A. Bensley, will be found in The .American Naturalist for 1901.7 
494 
