and a few species had thus acquired a great
advantage over other organisms, a comparatively short time would be
necessary to produce many divergent forms, which would spread
rapidly and widely throughout the world....

In geological treatises, published not many years ago, mammals were
always spoken of as having abruptly come in at the commencement of
the tertiary series. And now one of the richest known accumulations
of fossil mammals belongs to the middle of the secondary series;
and true mammals have been discovered in the new red sandstone at
nearly the commencement of this great series. Cuvier used to urge
that no monkey occurred in any tertiary stratum; but now extinct
species have been discovered in India, South America, and in Europe
as far back as the miocene stage. Had it not been for the rare
accident of the preservation of footsteps in the new red sandstone
of the United States, who would have ventured to suppose that, no
less than at least thirty kinds of bird-like animals, some of
gigantic size, existed during that period? Not a fragment of bone
has been discovered in these beds. Not long ago palaeontologists
maintained that the whole class of birds came suddenly into
existence during the eocene period; but now we know, on the
authority of Professor Owen, that a bird certainly lived during the
deposition of the upper green-sand. And still more recently that
strange bird, the Archeopteryx ... has been discovered in the
oolitic slates of Solenhofen. Hardly any recent discovery shows
more forcibly than this, how little we as yet know of the former
inhabitants of the world.

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 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 recognized; from all these
circumstances, I inferred that had sessile cirripedes existed
during the secondary