[Footnote 1: _The Nineteenth Century._]
[Footnote 2: Earlier, if more recent announcements are correct.]
[Footnote 3: It may be objected that I have not put the case fairly
inasmuch as the solitary insect's wing which was discovered twelve
months ago in Silurian rocks, and which is, at present, the sole
evidence of insects older than the Devonian epoch, came from strata of
Middle Silurian age, and is therefore older than the scorpions which,
within the last two years, have been found in Upper Silurian strata in
Sweden, Britain, and the United States. But no one who comprehends the
nature of the evidence afforded by fossil remains would venture to say
that the non-discovery of scorpions in the Middle Silurian strata, up
to this time, affords any more ground for supposing that they did not
exist, than the non-discovery of flying insects in the Upper Silurian
strata, up to this time, throws any doubt on the certainty that they
existed, which is derived from the occurrence of the wing in the Middle
Silurian. In fact, I have stretched a point in admitting that these
fossils afford a colourable pretext for the assumption that the land and
air-population were of contemporaneous origin.]