am, two from the Aru Islands,
one from Jobie, one from New Britain, and three from New Guinea--but of
these last one is confined to the northern and another to the southern part
of the island.

This law, of the distribution of allied species in separate areas--which is
found to apply more or less accurately to all classes of animals--is so
entirely opposed to the crowding together of no less that fifteen species
of wingless birds in the small area of New Zealand, that the idea is at
once suggested of great geographical changes. Captain Hutton points out
that if the islands from Ceram to New Britain {479} were to become joined
together, we should have a large number of species of cassowary (perhaps
several more than are yet discovered) in one land area. If now this land
were gradually to be submerged, leaving a central elevated region, the
different species would become crowded together in this portion just as the
moas and kiwis were in New Zealand. But we also require, at some remote
epoch, a more or less complete union of the islands now inhabited by the
separate species of cassowaries, in order that the common ancestral form
which afterwards became modified into these species, could have reached the
places where they are now found; and this gives us an idea of the complete
series of changes through which New Zealand is believed to have passed in
order to bring about its abnormally dense population of wingless birds.
First, we must suppose a land connection with some country inhabited by
struthious birds, from which the ancestral forms might be derived;
secondly, a separation into many considerable islands, in which the various
distinct species might become differentiated; thirdly, an elevation
bringing about the union of these islands to unite the distinct species in
one area; and fourthly, a subsidence of a large part of the area, leaving
the present islands with the various species crowded together.

If New Zealand has really gone through such a series of changes as here
suggested, some proofs of it might perhaps be obtained in the outlying
islands which were once, presumably, joined with it. And this gives great
importance to the statement of the aborigines of the Chatham Islands, that
the Apteryx formerly lived there but was exterminated about 1835. It is to
be hoped that some search will be made here and also in Norfolk Island, in
both of which it is not improbable remains either of Apteryx or Dinornis
might be d