ng the Middle and Upper Eocene
epochs. Hence it becomes highly probable that the well-known
similarities, and no less remarkable differences between the present
Faunae of India and South Africa have arisen in some such fashion as the
following. Some time during the Miocene epoch, possibly when the
Himalayan chain was elevated, the bottom of the nummulitic sea was
upheaved and converted into dry land, in the direction of a line
extending from Abyssinia to the mouth of the Ganges. By this means, the
Dekhan on the one hand, and South Africa on the other, became connected
with the Miocene dry land and with one another. The Miocene mammals
spread gradually over this intermediate dry land; and if the condition of
its eastern and western ends offered as wide contrasts as the valleys of
the Ganges and Arabia do now, many forms which made their way into Africa
must have been different from those which reached the Dekhan, while
others might pass into both these sub-provinces.

That there was a continuity of dry land between Europe and North America
during the Miocene epoch, appears to me to be a necessary consequence of
the fact that many genera of terrestrial mammals, such as _Castor,
Hystrix, Elephas, Mastodon, Equus, Hipparion, Anchitherium, Rhinoceros,
Cervus, Amphicyon, Hyoenarctos_, and _Machairodus_, are common to the
Miocene formations of the two areas, and have as yet been found (except
perhaps _Anchitherium_) in no deposit of earlier age. Whether this
connection took place by the east, or by the west, or by both sides of
the Old World, there is at present no certain evidence, and the question
is immaterial to the present argument; but, as there are good grounds for
the belief that the Australian province and the Indian and South-African
sub-provinces were separated by sea from the rest of Arctogaea before the
Miocene epoch, so it has been rendered no less probable, by the
investigations of Mr. Carrick Moore and Professor Duncan, that Austro-
Columbia was separated by sea from North America during a large part of
the Miocene epoch.

It is unfortunate that we have no knowledge of the Miocene mammalian
fauna of the Australian and Austro-Columbian provinces; but, seeing that
not a trace of a Platyrrhine Ape, of a Procyonine Carnivore, of a
characteristically South-American Rodent, of a Sloth, an Armadillo, or an
Ant-eater has yet been found in Miocene deposits of Arctogaea, I cannot
doubt that they already existed in the M