134 A NATURALIST IN TASMANIA ch. 



It was suggested long ago that a part at least 

 of the Australian flora and fauna has been derived 

 from an Antarctic continent that sent projecting 

 rays of land to join with the southernmost ex- 

 tension of Tasmania, South America and New 

 Zealand. This explanation of the many elements 

 possessed in common by these countries was 

 rejected by Wallace, and has never entered very 

 much into favour with naturalists, as it has 

 been supported by very dubious evidence, — for 

 instance, the occurrence in the now widely separ- 

 ated land masses of the southern hemisphere of 

 such birds as the Parrots, and the various members 

 of the Ostrich tribe, viz. the Ostrich in South 

 Africa, the Rhea in South America, the Cassowary 

 and Emu in Australia, and the Moa in New Zealand. 

 Whatever may be the true history of the routes 

 of migration of these and similar forms, the fact 

 that the tropics are no barrier to their distribution 

 makes the assumption of an Antarctic continent 

 or any more direct connexion between the south- 

 ern land masses unnecessary. But the case of 

 the Alpine and typically temperate forms of the 

 southern hemisphere which are not known, either 

 themselves or their allies, to be capable of living 

 or of ever having lived in the tropics, is altogether 

 different. In South America the lofty chain of 

 the Andes has permitted a migration of temperate 

 forms from north to south through the tropics, but 

 in the Australian region there is no such highland 

 bridge over which the northern forms could have 



