lace the union very far back, to account for the total want of
identity between the winged birds of New Zealand and those peculiar to
Australia, and a similar want of accordance in the lizards, the fresh-water
fishes, and the more important insect-groups of the two countries. From
what we know of the long geological duration of the generic types of these
groups we must certainly go back to the earlier portion of the Tertiary
period at least, in order that there should be such a complete disseverance
as exists between the characteristic animals of the two countries; and we
must further suppose that, since their separation, there has been no
subsequent union or sufficiently near approach to allow of any important
intermigration, even of winged birds, between them. It seems probable,
therefore, that {485} the Bampton shoal west of New Caledonia, and Lord
Howe's Island further south, formed the western limits of that extensive
land in which the great wingless birds and other isolated members of the
New Zealand fauna were developed. Whether this early land extended eastward
to the Chatham Islands and southward to the Macquaries we have no means of
ascertaining, but as the intervening sea appears to be not more than about
1,500 fathoms deep it is quite possible that such an amount of subsidence
may have occurred. It is possible, too, that there may have been an
extension northward to the Kermadec Islands, and even further to the Tonga
and Fiji Islands, though this is hardly probable, or we should find more
community between their productions and those of New Zealand.

A southern extension towards the Antarctic continent at a somewhat later
period seems more probable, as affording an easy passage for the numerous
species of South American and Antarctic plants, and also for the identical
and closely allied fresh-water fishes of these countries.

The subsequent breaking up of this extensive land into a number of separate
islands in which the distinct species of moa and kiwi were developed--their
union at a later period, and the final submergence of all but the existing
islands, is a pure hypothesis, which seems necessary to explain the
occurrence of so many species of these birds in a small area but of which
we have no independent proof. There are, however, some other facts which
would be explained by it, as the presence of three peculiar but allied
genera of starlings, the three species of parrots of the genus Nestor, and
the si