The Descent of Man

great kingdom of the Vertebrata it has culminated
in man. It must not, however, be supposed
that groups of organic beings are always supplanted,
and disappear as soon as they have
given birth to other and more perfect groups.
The latter, though victorious over their predecessors,
may not have become better adapted
for all places in the economy of nature. Some
old forms appear to have survived from inhabiting
protected sites, where they have not been
exposed to very severe competition; and these
often aid us in constructing our genealogies, by
giving us a fair idea of former and lost populations.
But we must not fall into the error of looking
at the existing members of any lowlyorganised
group as perfect representatives of
their ancient predecessors.
The most ancient progenitors in the kingdom of
the Vertebrata, at which we are able to obtain
an obscure glance, apparently consisted of a
group of marine animals (32. The inhabitants of