in Borneo and Sumatra, while the Javanese species occurs in Burma and even in
Bengal. Among birds, the small ground-dove, Geopelia striata, and the curious
bronze-coloured magpie, Crypsirhina varians, are common to Java and Siam;
while there are in Java species of Pteruthius, Arrenga, Myiophonus, Zoothera,
Sturnopastor, and Estrelda, the near allies of which are found in various parts of
India, while nothing like them is known to inhabit Borneo or Sumatra.
Such a curious phenomenon as this can only be understood by supposing that,
subsequent to the separation of Java, Borneo became almost entirely submerged,
and on its re-elevation was for a time connected with the Malay peninsula and
Sumatra, but not with Java or Siam. Any geologist who knows how strata have
been contorted and tilted up, and how elevations and depressions must often
have occurred alternately, not once or twice only, but scores and even hundreds
of times, will have no difficulty in admitting that such changes as have been here
indicated, are not in themselves improbable. The existence of extensive coal-
beds in Borneo and Sumatra, of such recent origin that the leaves which abound
in their shales are scarcely distinguishable from those of the forests which now
cover the country, proves that such changes of level actually did take place; and
it is a matter of much interest, both to the geologist and to the philosophic
naturalist, to be able to form some conception of the order of those changes, and
to understand how they may have resulted in the actual distribution of animal
life in these countries; a distribution which often presents phenomena so strange
and contradictory, that without taking such changes into consideration we are
unable even to imagine how they could have been brought about.