basin began to be laid down, an arm of the
sea broke up the connection which once subsisted between Australia and
the rest of the world, probably by a land bridge, _via_ Java, Sumatra,
the Malay peninsula, and Asia generally. 'But how do you know,' asks the
candid inquirer, 'that such a connection ever existed at all?' Simply
thus, most laudable investigator--because there are large land mammals
in Australia. Now, large land mammals do not swim across a broad ocean.
There are none in New Zealand, none in the Azores, none in Fiji, none in
Tahiti, none in Madeira, none in Teneriffe--none, in short, in any
oceanic island which never at any time formed part of a great continent.
How could there be, indeed? The mammals must necessarily have got there
from somewhere; and whenever we find islands like Britain, or Japan, or
Newfoundland, or Sicily, possessing large and abundant indigenous
quadrupeds, of the same general type as adjacent continents, we see at
once that the island must formerly have been a mere peninsula, like
Italy or Nova Scotia at the present day. The very fact that Australia
incloses a large group of biggish quadrupeds, whose congeners once
inhabited Europe and America, suffices in itself to prove beyond
question that uninterrupted land communication must once have existed
between Australia and those distant continents.

In fact, to this day a belt of very deep sea, known as Wallace's Line,
from the great naturalist who first pointed out its far-reaching
zoological importance, separates what is called by science 'the
Australian province' on the southwest from 'the Indo-Malayan province'
to the north and east of it. This belt of deep sea divides off sharply
the plants and animals of the Australian type from those of the common
Indian and Burmese pattern. South of Wallace's Line we now find several
islands, big and small, including New Guinea, Australia, Tasmania, the
Moluccas, Celebes, Timor, Amboyna, and Banda. All these lands, whose
precise geographical position on the map must of course be readily
remembered, in this age of school boards and universal examination, by
every pupil-teacher and every Girton girl, are now divided by minor
straits of much shallower water; but they all stand on a great submarine
bank, and obviously formed at one time parts of the same wide Australian
continent, because animals of the Australian type are still found in
every one of them. No Indian or Malayan animal, however, of the