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 by way 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 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 
