the basis of the flora is Australian with a large intermixture of
northern and southern temperate forms and others which have remote
world-wide affinities.

_General Features of the Australian Flora and its Probable Origin._--Before
proceeding to point out how the peculiarities of the New Zealand flora may
be best accounted for, it is necessary to consider briefly what are the
main peculiarities of Australian vegetation, from which so important a part
of that of New Zealand has evidently been derived.

The actual Australian flora consists of two great divisions--a temperate
and a tropical, the temperate being again divisible into an eastern and a
western portion. All that is most characteristic of the Australian flora
belongs to the temperate division (though these often overspread the whole
continent), in which are found almost all the remarkable Australian types
of vegetation and the numerous genera peculiar to this part of the world.
Contrary to what occurs in most other countries, the {492} tropical appears
to be less rich in species and genera than the temperate region, and what
is still more remarkable it contains fewer peculiar species, and very few
peculiar genera. Although the area of tropical Australia is about equal to
that of the temperate portions, and it has now been pretty well explored
botanically, it has probably not more than half as many species.[129]
Nearly 500 of its species are identical with Indian or Malayan plants, or
are very close representatives of them; while there are more than 200
Indian genera, confined for the most part to the tropical portion of
Australia. The remainder of the tropical flora consists of a few species
and many genera of temperate {493} Australia which range over the whole
continent, but these form only a small portion of the peculiarly Australian
genera.

These remarkable facts clearly point to one conclusion--that the flora of
tropical Australia is, comparatively, recent and derivative. If we imagine
the greater part of North Australia to have been submerged beneath the
ocean, from which it rose in the middle or latter part of the Tertiary
period, offering an extensive area ready to be covered by such suitable
forms of vegetation as could first reach it, something like the present
condition of things would inevitably arise. From the north, widespread
Indian and Malay plants would quickly enter, while from the south the most
dominant forms of warm-temperate Australia, a