492 



ISLAND LIFE. 



[part II. 



others, have reached Australia by the route already indicated. 

 The second set of Australo-European genera, however, and 

 many others characteristic of the South European or the Hima- 

 layan 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, 

 indicates the route of this immigration, and sufficiently explains 

 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 ly way of the African HigJilands. — 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 repre- 

 sentation of the northern 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 

 temperate plants in South Africa, none of which occur in 

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

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

 clear, therefore, that South Africa has received its European 

 plants by the direct route through the Abyssinian highlands 



