a, as deduced from its geological
structure and the main features of its existing and Tertiary flora, to the
period {499} when New Zealand was first brought into close connection with
it, by means of a great north-western extension of that country, which, as
already explained in our last chapter, is so clearly indicated by the form
of the sea bottom (See Map, p. 471). The condition of New Zealand previous
to this event is very obscure. That it had long existed as a more or less
extensive land is indicated by its ancient sedimentary rocks; while the
very small areas occupied by Jurassic and Cretaceous deposits, imply that
much of the present land was then also above the sea-level. The country had
probably at that time a scanty vegetation of mixed Antarctic and Polynesian
origin; but now, for the first time, it would be open to the free
immigration of such Australian types as were suitable to its climate, and
which _had already reached the tropical and sub-tropical portions of the
Eastern Australian island_. It is here that we obtain the clue to those
strange anomalies and contradictions presented by the New Zealand flora in
its relation to Australia, which have been so clearly set forth by Sir
Joseph Hooker, and which have so puzzled botanists to account for. But
these apparent anomalies cease to present any difficulty when we see that
the Australian plants in New Zealand were acquired, not directly, but, as
it were, at second hand, by union with an island which itself had as yet
only received a portion of its existing flora. And then, further
difficulties were placed in the way of New Zealand receiving such an
adequate representation of that portion of the flora which had reached East
Australia as its climate and position entitled it to, by the fact of the
union being, not with the temperate, but with the tropical and sub-tropical
portions of that island, so that only those groups could be acquired which
were less exclusively temperate, and had already established themselves in
the warmer portion of their new home.[134]

{500}

It is therefore no matter of surprise, but exactly what we should expect,
that the great mass of pre-eminently temperate Australian genera should be
absent from New Zealand, including the whole of such important families as,
Dilleniaceae, Tremandreae, Buettneriacae, Polygaleae, Casuarineae and
Haemodoraceae; while others, such as Rutaceae, Stackhousieae, Rhamneae,
Myrtaceae, Proteaceae, and Santa