In a memoir on Fossil Sessile Cirripedes, I
have stated that, from the number of existing and extinct tertiary
species; from the extraordinary abundance of the individuals of many
species all over the world, from the Arctic regions to the equator,
inhabiting various zones of depths from the upper tidal limits to 50
fathoms; from the perfect manner in which specimens are preserved in
the oldest tertiary beds; from the ease with which even a fragment of
a valve can be recognised; from all these circumstances, I inferred
that had sessile cirripedes existed during the secondary periods, they
would certainly have been preserved and discovered; and as not one
species had been discovered in beds of this age, I concluded that this
great group had been suddenly developed at the commencement of the
tertiary series. This was a sore trouble to me, adding as I thought
one more instance of the abrupt appearance of a great group of
species. But my work had hardly been published, when a skilful
palaeontologist, M. Bosquet, sent me a drawing of a perfect specimen
of an unmistakeable sessile cirripede, which he had himself extracted
from the chalk of Belgium. And, as if to make the case as striking as
possible, this sessile cirripede was a Chthamalus, a very common,
large, and ubiquitous genus, of which not one specimen has as yet been
found even in any tertiary stratum. Hence we now positively know that
sessile cirripedes existed during the secondary period; and these
cirripedes might have been the progenitors of our many tertiary and
existing species.
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