s belonging to the "Ancient
Continental Islands," for though usually described as wholly volcanic, it
is, more probably, an island of varied geological structure buried under
the lavas of its numerous volcanoes. But of late years extensive Tertiary
deposits of Miocene age have been discovered, showing that it is not a mere
congeries of {451} volcanoes; it is connected with the British Islands and
with Greenland by seas less than 500 fathoms deep; and it possesses a few
mammalia, one of which is peculiar, and at least three peculiar species of
birds. It was therefore almost certainly united with Greenland, and
probably with Europe by way of Britain, in the early part of the Tertiary
period, and thus afforded one of the routes by which that intermigration of
American and European animals and plants was effected which we know
occurred during some portion of the Eocene and Miocene periods, and
probably also in the Pliocene. The fauna and flora of this island are,
however, so poor, and offer so few peculiarities, that it is unnecessary to
devote more time to their consideration.

There remains the great Malay island--Celebes, which, owing to its
possession of several large and very peculiar mammalia, must be classed,
zoologically, as "ancient continental"; but whose central position and
relations both to Asia and to Australia render it very difficult to decide
in which of the primary zoological regions it ought to be placed, or
whether it has ever been united with either of the great continents.
Although I have pretty fully discussed its zoological peculiarities and
past history in my _Geographical Distribution of Animals_, it seems
advisable to review the facts on the present occasion, more especially as
the systematic investigation of the characteristics of continental islands
we have now made will place us in a better position for determining its
true zoo-geographical relations.

_Physical Features of Celebes._--This large and still comparatively
unexplored island is interesting to the geographer on account of its
remarkable outline, but much more so to the zoologist for its curious
assemblage of animal forms. The geological structure of Celebes is almost
unknown. The extremity of the northern peninsula is volcanic; while in the
southern peninsula there are extensive deposits of a crystalline limestone,
in some places overlying basalt. Gold is found in the northern peninsula
and in the central mass, as well as iron, tin,