ate varieties which will at first probably exist in the
intermediate zones, will be liable to be supplanted by the allied forms on
either hand; and the latter, from existing in greater numbers, will
generally be modified and improved at a quicker rate than the intermediate
varieties, which exist in lesser numbers; so that the intermediate
varieties will, in the long run, be supplanted and exterminated.

On this doctrine of the extermination of an infinitude of connecting links,
between the living and extinct inhabitants of the world, and at each
successive period between the extinct and still older species, why is not
every geological formation charged with such links? Why does not every
collection of fossil remains afford plain evidence of the gradation and
mutation of the forms of life? We meet with no such evidence, and this is
the most obvious and forcible of the many objections which may be urged
against my theory. Why, again, do whole groups of allied species appear,
though certainly they often falsely appear, to have come in suddenly on the
several geological stages? Why do we not find great piles of strata beneath
the Silurian system, stored with the remains of the progenitors of the
Silurian groups of fossils? For certainly on my theory such {464} strata
must somewhere have been deposited at these ancient and utterly unknown
epochs in the world's history.

I can answer these questions and grave objections only on the supposition
that the geological record is far more imperfect than most geologists
believe. It cannot be objected that there has not been time sufficient for
any amount of organic change; for the lapse of time has been so great as to
be utterly inappreciable by the human intellect. The number of specimens in
all our museums is absolutely as nothing compared with the countless
generations of countless species which certainly have existed. We should
not be able to recognise a species as the parent of any one or more species
if we were to examine them ever so closely, unless we likewise possessed
many of the intermediate links between their past or parent and present
states; and these many links we could hardly ever expect to discover, owing
to the imperfection of the geological record. Numerous existing doubtful
forms could be named which are probably varieties; but who will pretend
that in future ages so many fossil links will be discovered, that
naturalists will be able to decide, on the common view,