were accumulating. The Malay Archipelago is one of
the richest regions of the whole world in organic beings; yet if all
the species were to be collected which have ever lived there, how
imperfectly would they represent the natural history of the world!

But we have every reason to believe that the terrestrial productions of
the archipelago would be preserved in an excessively imperfect manner in
the formations which we suppose to be there accumulating. I suspect that
not many of the strictly littoral animals, or of those which lived on
naked submarine rocks, would be embedded; and those embedded in gravel
or sand, would not endure to a distant epoch. Wherever sediment did not
accumulate on the bed of the sea, or where it did not accumulate at a
sufficient rate to protect organic bodies from decay, no remains could
be preserved.

In our archipelago, I believe that fossiliferous formations could be
formed of sufficient thickness to last to an age, as distant in futurity
as the secondary formations lie in the past, only during periods of
subsidence. These periods of subsidence would be separated from each
other by enormous intervals, during which the area would be either
stationary or rising; whilst rising, each fossiliferous formation
would be destroyed, almost as soon as accumulated, by the incessant
coast-action, as we now see on the shores of South America. During the
periods of subsidence there would probably be much extinction of life;
during the periods of elevation, there would be much variation, but the
geological record would then be least perfect.

It may be doubted whether the duration of any one great period of
subsidence over the whole or part of the archipelago, together with
a contemporaneous accumulation of sediment, would EXCEED the average
duration of the same specific forms; and these contingencies are
indispensable for the preservation of all the transitional gradations
between any two or more species. If such gradations were not fully
preserved, transitional varieties would merely appear as so many
distinct species. It is, also, probable that each great period of
subsidence would be interrupted by oscillations of level, and that
slight climatal changes would intervene during such lengthy periods; and
in these cases the inhabitants of the archipelago would have to migrate,
and no closely consecutive record of their modifications could be
preserved in any one formation.

Very many of the marine inh