e fossiliferous deposits in the world, even if they could be
thoroughly explored, would still prove highly imperfect, considered as a
history of extinct forms of life. In order that many of these forms
should have been preserved as fossils, it is necessary that they should
have died upon a surface neither too hard nor too soft to admit of their
leaving an impression; that this surface should afterwards have
hardened sufficiently to retain the impression; that it should then have
been protected from the erosion of water, as well as from the
disintegrating influence of the air; and yet that it should not have
sunk far enough beneath the surface to have come within the no less
disintegrating influence of subterranean heat. Remembering thus, as a
general rule, how many conditions require to have met before a fossil
can have been both formed and preserved, we must conclude that the
geological record is probably as imperfect in itself as are our
opportunities of reading even the little that has been recorded. If we
speak of it as a history of the succession of life upon the planet, we
must allow, on the one hand, that it is a history which merits the name
of a "chapter of accidents"; and, on the other hand, that during the
whole course of its compilation pages were being destroyed as fast as
others were being formed, while even of those that remain it is only a
word, a line, or at most a short paragraph here and there, that we are
permitted to see. With so fragmentary a record as this to study, I do
not think it is too much to say that no conclusions can be fairly based
upon it, merely from the absence of testimony. Only if the testimony
were positively opposed to the theory of descent, could any argument be
fairly raised against that theory on the grounds of this testimony. In
other words, if any of the fossils hitherto discovered prove the order
of succession to have been incompatible with the theory of genetic
descent, then the record may fairly be adduced in argument, because we
should then be in possession of definite information of a positive
kind, instead of a mere absence of information of any kind. But if the
adverse argument reaches only to the extent of maintaining that the
geological record does not furnish us with so complete a series of
"connecting links" as we might have expected, then, I think, the
argument is futile. Even in the case of human histories, written with
the intentional purpose of conveying informat