region to the other in a few days, without ever being out of
sight of land.

The inference that we must draw from these facts is, undoubtedly,
that the whole of the islands eastwards beyond Java and Borneo do
essentially form a part of a former Australian or Pacific
continent, although some of them may never have been actually
joined to it. This continent must have been broken up not only
before the Western Islands were separated from Asia, but probably
before the extreme southeastern portion of Asia was raised above
the waters of the ocean; for a great part of the land of Borneo
and Java is known to be geologically of quite recent formation,
while the very great difference of species, and in many cases of
genera also, between the productions of the Eastern Malay Islands
and Australia, as well as the great depth of the sea now
separating them, all point to a comparatively long period of
isolation.

It is interesting to observe among the islands themselves how a
shallow sea always intimates a recent land connexion. The Aru
Islands, Mysol, and Waigiou, as well as Jobie, agree with New
Guinea in their species of mammalia and birds much more closely
than they do with the Moluccas, and we find that they are all
united to New Guinea by a shallow sea. In fact, the 100-fathom
line round New Guinea marks out accurately the range of the true
Paradise birds.

It is further to be noted--and this is a very interesting point
in connection with theories of the dependence of special forms of
life on external conditions--that this division of the