In the struggle for existence between the newer and the older forms, the older forms were gradually driven southwards towards the diverging fringes of the land masses. The vanquished left behind them on the field of battle only their bones, to become fossils. Sometimes succeeding waves swept along to the extreme limits of the land, and many early types were utterly destroyed. But others found sanctuary in the ends of the South, and such survivors of older and earlier types of life cause a similarity between the southern lands that Huxley called Notogæa, although the extent of his region must be increased. Recently, however, there has been a recurrence to Huxley's suggested union of South America and Australia, based on new evidence of a direct kind, quite different from that which had just been given. Various groups of naturalists have stated that there are similarities between the invertebrate inhabitants of Australia and of South America of a kind which makes the existence of a direct land connection in the Southern Hemisphere extremely probable. Moreover, Ameghino has recently described some marsupial fossils from South America which, he states, belong to the Australian group of Dasyuridæ, and Oldfield Thomas has described a new mammal from South America which is unlike the opossums of America and like the diprotodonts of Australia. So that, while the general opinion has been against Huxley's division, Notogæa, in the strict meaning which he gave to it, there has recently been an opinion growing in its favour. Huxley also made minor alterations in Mr. Sclater's scheme by forming an additional circumpolar region for the Northern Hemisphere, and by elevating New Zealand into a separate region, distinct from Australia. On these points there is a balance of opinion against his views.