624 



ISLAND LIFE 



PART It 



and about half in South Temperate America or New Zea- 

 land ; whence we may conclude that most of these, as well 

 as some others, have reached Australia by the route already 

 indicated. The second set of Australo-European genera, 

 however, and many others characteristic of the South Euro- 

 pean or the Himalayan flora, have probably reached 

 Australia by way of the mountains of Southern Asia, 

 Borneo, the Moluccas, and New Guinea, at a somewhat 

 remote period when loftier ranges and some intermediate 

 peaks may have existed, sufficient to carry on the migration 

 by the aid of the alternate climatal changes which are 

 known to have occurred. The long belt of Secondary and 

 Palaeozoic formations in East Australia from Tasmania to 

 Cape York continued by the lofty ranges of New Guinea, in- 

 dicates the route of this immigration, and sufficiently ex- 

 plains how it is that these northern types are almost wholly 

 confined to this part of the Australian continent. Some of 

 the earlier immigrants of this class no doubt passed over to 

 New Zealand and now form a portion of the peculiar genera 

 confined to these two countries ; but most of them are of 

 later date, and have thus remained in Australia only. 



Proofs of Migration by luay of the African Highlands. — 

 It is owing to this twofold current of vegetation flowing 

 into Australia by widely different routes that we have in 

 this distant land a better representation of the European 

 flora, both as regards species and genera, than in any other 

 part of the southern hemisphere ; and, so far as I can judge 

 of the facts, there is no general phenomenon — that is, 

 nothing in the distribution of genera and other groups of 

 plants as opposed to cases of individual species — that is 

 not fairly accounted for by such an origin. It further 

 receives support from the case of South Africa, which also 

 contains a large and important representation of the north- 

 ern flora. But here we see no indications (or very slight 

 ones) of that southern influx which has given Australia 

 such a community of vegetation with the Antarctic lands. 

 There are no less than sixty genera of strictly north tem- 

 perate plants in South Africa, none of which occur in Aus- 

 tralia ; while very few of the species, so characteristic of 

 Australia, New Zealand, and Fuegia, are found there. It 



