robably inhabited Europe, which at
that epoch enjoyed a sub-tropical climate; and this is rendered almost
certain by the discovery in the Miocene of France of fossil remains of
trogons and jungle-fowl. If, then, these Indian birds date back to the very
period during which alone Lemuria could have existed, that continent was
quite unnecessary for their introduction into Madagascar, as they could
have followed the same track as the mammalia of Miocene Europe and Asia;
while if, as I maintain, they are of more recent date, then Lemuria had
ceased to exist, and could not have been the means of their introduction.

_Submerged Islands between Madagascar and India._--Looking at the
accompanying map of the Indian Ocean, we see that between Madagascar and
India there are now extensive shoals and coral reefs, such as are usually
held to indicate subsidence; and we may therefore fairly postulate the
former existence here of several large islands, some of them not much
inferior to Madagascar itself. These reefs are all separated from each
other by very deep {425} sea--much deeper than that which divides
Madagascar from Africa, and we have therefore no reason to imagine their
former union. But they would nevertheless greatly facilitate the
introduction of Indian birds into the Mascarene Islands and Madagascar; and
these facilities existing, such an immigration would be sure to take place,
just as surely as American birds have entered the Galapagos and Juan
Fernandez, as European birds now reach the Azores, and as Australian birds
reach such a distant island as New Zealand. This would take place the more
certainly because the Indian Ocean is a region of violent periodical storms
at the changes of the monsoons, and we have seen in the case of the Azores
and Bermuda how important a factor this is in determining the transport of
birds across the ocean.

[Illustration: MAP OF THE INDIAN OCEAN.

Showing the position of banks less than 1,000 fathoms deep between Africa
and the Indian Peninsula.]

{426}

The final disappearance of these now sunken islands does not, in all
probability, date back to a very remote epoch; and this exactly accords
with the fact that some of the birds, as well as the fruit-bats of the
genus Pteropus, are very closely allied to Indian species, if not actually
identical, others being distinct species of the same genera. The fact that
not one closely-allied species or even genus of Indian or Malayan mammals
is