32

27
ductory Essay to the Flora Tasmanieae*), does not go so far as this,
although he, too, says, "that 216 or one-fourth of the New Zealand
Phaenogams are natives of Australia, and of these 115 species are con-
fined to these two countries;" and, "that of the 115 specimens pecu-
liar to Australia and New Zealand, only 26 belong to genera peculiar
to those countries, and only 6 to the long list of Australian genera
which contain upwards of 20 species each." Nevertheless it is believed
that this comparison will be very materially altered, when the whole of
the Flora of New Zeland (and the many other Polynesian Islands)
shall be fully known. Already, since the publication of the Flora
Novae-Zelandiae, have many new species been discovered in New Zea-
land, particularly in the Middle Island; where too, are several South
American genera hitherto not detected in the North Island, (as Donatia,
Rostkovia, Gaimardia, etc), and, consequently, not referred to in this
Essasy. And of those 26 species belonging to genera at present only
common to Australia and New Zealand, may it not reasonably be ex-
pected, that some of these will be also found in the many unexplored
sub-tropical islands? Again, seeing that the striking characteristic
Australian genera (while found in Tasmania) are wholly wanting in
New Zealand; and that the characteristic New Zealand genera are
also (as such) wantng in Australia; is it not evident, that it is not so
much from what is (the positive), as from what is not (the negative),
that the better comparison can in this case be drawn, and the truer
Botanical affinity deduced? Reviewing, then, what is already known
of New Zealand and Southern insular Botany, and looking forward
expectingly to future kindred revelations, it is not unreasonably be-
lieved, that the Botany of the New Zealand group will be found to be
peculiar, and not so closely related with the nearest mainland (Aus[tra]
lia), as with many other small islands, and therefore, forming with
them a Southern Botanical insular region, of which New Zealand is
probably about the existing centre.

22. In bringing this necessarly imperfect outline of the Botanical
Geography of the North Island to a close, many such thoughts as the
following present themselves for consderation:-
Is there a natural law affecting the dissemination of plants?
Is a climatic, or geognostic, difference, of greater value than a mere
geographical one?
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* Page 1xxxviii.:An admirable work, well worthy the serious study of every
student of New Zealand Botany.