The existence, at these and other distant points of the southern hemisphere, of species which, though distinct, belong to genera exclusively confined to the south, is a more remarkable case.

Some of these species are so distinct that we cannot suppose that there has been time since the commencement of the last glacial period for their migration and subsequent modification to the necessary degree." Mr.
Darwin goes on to account for these facts by the probable existence of a rich antarctic flora in a warm period anterior to the last glacial {151} epoch.

There are indeed many reasons for thinking that a southern continent, rich in living forms, once existed.

One such reason is the way in which struthious birds are, or have been, distributed around the antarctic region: as the ostrich in Africa, the rhea in South America, the emeu in Australia, the apteryx, dinornis, &c.

in New Zealand, the epiornis in Madagascar.