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Show 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 Himalayan flora, have probably reached Australia by wa.y of the mountains of Southern Asia, Borneo, the Moluccas, and New Guinea at a somewhat remote period. when loftier ranges and some i~termediate 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 Palreozoic formations in East Australia from Tasmania to Cape York, continued by the lofty ranges of New Guine<t, 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 immiarants of this class no doubt passed over to New Zealand 0 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 \ cnAP. xxm.] AUCTIC PLANTS IN NEW ZEALAND. 493 an~ the lofty equatorial mountains, and mostly at a distant penod when the conditions for migration were somewhat more favourable than th ey are now. Th e much greater di.r ectness of the ~oute from Northern Europe to South Africa than to Austr~ha ; ~nd the existence even now of lofty mountains and exten~I ve highlands for a large portion of the distance will explam ( h t s· J , w a Ir oseph Hooker notes as " a very cuJr ious fact ) why South ~frica ~as more very northern European gene:a than Australia, while Australia has more identical specMs and a better representation on the whole of the Eur~pea.n flora-this being clearly due to the large influx of speCies It ~as received from the Antarctic Islands, in addition t~ those whwh have entered it by way of Asia. The greater dtstance of South Africa even now from any of these islands and ~he much deeper sea to the south of the African continent: than m the case of Tasmania and New Zealand, indicating a S~laller recent extension southward, is all quite in harmony With the facts of distribution of the northern flora above referred to. Sul!posed Connection of South Africa and Australia.-There remams, ho';'ever, the small amount of direct affinity between the vegetatiOn of South Africa and that of Australia New Zealand, and rremperate South America, consisting in' all of fifteen genera, five of which are confined to Australia and ~outh Africa, while several natural orders are better represented m .these two countries than in any other part of the world. This re~emblance has been supposed to imply some former landconnectiOn of all the great southern lands, but it appears to me that any such supposition is wholly unnecessary. The differences between the faunas and floras of these countries are too gre~t and too radical to render it possible that any such conn~ctwn should have existed except at a very remote period. ~ut If we have to go back so far for an explanation, a much Simpler one presents itself, and one more in accordance with what we ha:e learnt of the general permanence of deep oceans a.nd the radical changes that have taken place in the distributiOn of. all ~orms of life. Just as we explain the presence of marsupmls m Australia and America and of Centetidre in |