314 ANTARCTICA: A VANISHED AUSTRAL LAND. 



above will, I tliiuk, account for them not less satisfactorily than tbat 

 by an entirely northern center of dispersion. Mr. Wallace' holds that 

 ''the three most important south temperate land areas — south tem- 

 perate America, South Africa, and Australia — have in all probabiHty 

 always been as widely separated from each other ;is now," and "that 

 it is unnecessary to suppose any land connection to explain the resem- 

 blance between their aninml and vegetable inhabitants," as he !:ionsiders 

 that the northern continuous land was the origin of them all, and that 

 they sjpread meridianally south. That many forms of life did thus 

 reach Notoga^a "under i^ressure" of glacial ej)ochs and "of more 

 specialized types" it is impossible to doubt. But, as 1 have already 

 remarked, this explanation will not account for marks of heredity seen 

 in such southern groups as the piping crows of Australia and the den- 

 drocolaptine birds of America, and the many other instances in tlie 

 same category enumerated by Professor I'arker. That their original 

 ancient progenitor may have come from the north is, of course, possible, 

 but the characters that prove a common parentage — in forms now so 

 diverse — could not have arisen in birds living so far apart as Australia 

 and South America, without, I believe, a large common land area on 

 which the progeny of the original parents could develop and spread 

 over. 



Mr. Wallace believes also that the ancestral forms of the marsupials 

 and monotremes reached West Australia (which for a long period in 

 secondary and primary times was separated oft' as an island from East 

 Australia, an arm of the sea uniting the Banda and the Antarctic seas) 

 from the north, through Java and the intervening islands or land in 

 that sea. Their fossil forms have, however, been chiefly found in East 

 Australia, or if found in West Australia, they occur in strata certainly 

 of no greater age. If such, indeed, were the route of their southward 

 march, it is remarkable that througlumt the extensive regions over 

 which they passed not a single individual has survived — not even in 

 Timor, an island of like vegetation and climate to Australia, and that 

 nearest to West Australia; while marsupials and monotremes are rep- 

 resented abundantly on the northern and eastern Papuasian islands, 

 with which West Australia, as IVfr. Wallace believes, was not at that 

 period in connection. That these gi oups may have originated in Antarc- 

 tica and spread into Australia via its Tasmanian peninsula, since fossils 

 presenting many afiinities with the Australian forms have recently been 

 discovered in Patagonia, appears to me a not less satisfactory explana- 

 tion of their distribution. Their absence so far fi'om New Zealand is 

 not more difficult to account for than their entire absence in the land 

 which, according to Mr. Wallace, they traversed. Again, as regards the 

 dispersal of the ancestors of the struthious birds, Mr. Wallace believes 

 that they reached East Australia from New Guinea, with which it was 

 united across Torres Strait; and that the emus, the cassowaries, the 



' Islaud Life, page. 5U7. 



