CHAP. XIII.] THE AUSTRALIAN REGION. 391 
Marsupialia and Monotremata, found nowhere else on the globe 
except a single family of the former in America. The Marsu- 
pials are wonderfully developed in Australia, where they exist . 
in the most diversified forms, adapted to different modes of life. 
Some are carnivorous, some herbivorous; some arboreal, others 
terrestrial. There are insect-eaters, root-gnawers, fruit-eaters, 
honey-eaters, leaf or grass-feeders. Some resemble wolves, 
others marmots, weasels, squirrels, flying squirrels, dormice or 
jerboas. They are classed in six distinct families, comprising 
about thirty genera, and subserve most of the purposes in the 
economy of nature, fulfilled in other parts of the world by very 
different groups; yet they all possess common peculiarities of 
structure and habits which show that they are members of 
one stock, and have no real affinity with the Old-World forms 
which they often outwardly resemble. 
The other order, Monotremata, is only represented by two rare 
and very remarkable forms, Ornithorhynchus and Echidna, pro- 
bably the descendants of some of those earlier developments of 
mammalian life which in every other part of the globe have long 
been extinct. 
The bats of Australia all belong to Old-World genera and 
possess no features of special interest, a result of the wandering 
habits of these aerial mammals. The Rodents are more interest-— 
ing. They are all more or less modified forms of mice or rats. 
Some belong to the widely distributed genus Mus, others to four 
allied genera, which may be all modifications of some common 
Old-World form. They spread all over Australia, and allied 
species occur in Celebes and the Papuan Islands; so that al- 
though not yet known from the Moluccas, there can be little 
doubt that some of them exist there. 
Birds.—The typical Australian region, as above defined, is 
almost as well characterized by its birds, as by its mammalia; 
but in this case the deficiencies are less conspicuous, while the 
peculiar and characteristic families are numerous and important. 
The most marked deficiency as regards wide-spread families, is 
the total absence of Fringillide (true finches), Picidee (wood- 
peckers), Vulturide (vultures), and Phasianide (pheasants) 
