South America and Australia 141 



life. We know that these arose successively, primitive 

 birds like the ostriches being older than higher forms 

 like the parrots and singing birds ; the pouched mar- 

 supials preceding the antelopes and the lion; the lemurs 

 coming befors the man-like apes. Each wave of life 

 spread over the whole area producing after its kind ; 

 then, pressing round the northern land area, it met a 

 thousand different conditions of environment, different 

 foods, enemies, and climates, and broke up into differ- 

 ent genera and species. But there was never a wave 

 of life that was not followed bv another wave. In the 

 struggle for existence between the newer and the older 

 forms, the older forms were gradually driven south- 

 wards 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 suc- 

 ceeding 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 Notogoea, 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 Aus- 

 tralia, 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 similar- 

 ities between the invertebrate inhabitants of Australia 

 and of South America of a kind which makes the exist- 

 ence of a direct land connection in the Southern Hemi- 

 sphere extremely probable. Moreover, Ameghino has 

 recently described some marsupial fossils from South 

 America which, he states, belong to the Australian 



