between the latest secondary and earliest tertiary
formation. But now we may read in the Supplement to Lyell's 'Manual,'
published in 1858, clear evidence of the existence of whales in the
upper greensand, some time before the close of the secondary period.

I may give another instance, which from having passed under my own eyes
has much struck me. 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.

The case most frequently insisted on by palaeontologists of the
apparently sudden appearance of a whole group of species, is that of the
teleostean fishes, low down in the Chalk period. This group includes the
large majority of existing species. Lately, Professor Pictet has carried
their existence one sub-stage further back; and some palaeontologists
believe that certain much older fishes, of which the affinities are as
yet imperfectly known, are really teleostean. Assuming, however, that
the whole of them did appear, as Agassiz believes, at t