iscovered.

So far we find nothing to object to in the speculations of Captain Hutton,
with which, on the contrary, we almost wholly concur; but we cannot follow
him when he goes on to suggest an Antarctic continent uniting New Zealand
and Australia with South America, and probably also with South Africa, in
order to explain the existing distribution {480} of struthious birds. Our
best anatomists, as we have seen, agree that both Dinornis and Apteryx are
more nearly allied to the cassowaries and emus than to the ostriches and
rheas; and we see that the form of the sea-bottom suggests a former
connection with North Australia and New Guinea--the very region where these
types most abound, and where in all probability they originated. The
suggestion that all the struthious birds of the world sprang from a common
ancestor at no very remote period, and that their existing distribution is
due to direct land communication between the countries they _now_ inhabit,
is one utterly opposed to all sound principles of reasoning in questions of
geographical distribution. For it depends upon two assumptions, both of
which are at least doubtful, if not certainly false--the first, that their
distribution over the globe has never in past ages been very different from
what it is now; and the second, that the ancestral forms of these birds
never had the power of flight. As to the first assumption, we have found in
almost every case that groups now scattered over two or more continents
formerly lived in intervening areas of existing land. Thus the marsupials
of South America and Australia are connected by forms which lived in North
America and Europe; the camels of Asia and the llamas of the Andes had many
extinct common ancestors in North America; the lemurs of Africa and Asia
had their ancestors in Europe, as had the trogons of South America, Africa,
and tropical Asia. But besides this general evidence we have direct proof
that the struthious birds had a wider range in past times than now. Remains
of extinct rheas have been found in Central Brazil, and those of ostriches
in North India; while remains, believed to be of struthious birds, are
found in the Eocene deposits of England; and the Cretaceous rocks of North
America have yielded the extraordinary toothed bird, Hesperornis, which
Professor O. Marsh declares to have been "a carnivorous swimming ostrich."

As to the second point, we have the remarkable fact that all known birds of
this g