the species which clearly appears to be the parent, co-exists
with one that has been evidently derived from it. Generally the
supposed parent also seems to have been modified, and then the
demonstration is not so clear, for some of the links in the chain
of variation are wanting. The process of origination of a species
in nature as it takes place successively, must be ever, perhaps,
beyond man's power to trace, on account of the great lapse of
time it requires. But we can obtain a fair view of it by tracing
a variable and far-spreading species over the wide area of its
present distribution; and a long observation of such will lead to
the conclusion that new species must in all cases have arisen out
of variable and widely-disseminated forms. It sometimes happens,
as in the present instance, that we find in one locality a
species under a certain form which is constant to all the
individuals concerned; in another exhibiting numerous varieties;
and in a third presenting itself as a constant form quite
distinct from the one we set out with. If we meet with any two of
these modifications living side by side, and maintaining their
distinctive characters under such circumstances, the proof of the
natural origination of a species is complete; it could not be
much more so were we able to watch the process step by step. It
might be objected that the difference between our two species is
but slight, and that by classing them as varieties nothing
further would be proved by them. But the differences between them
are such as obtain between allied species generally. Large genera
are composed in great part of such species, and it is interesting
to show the great and beautiful diversity within a large genus as
brought about by the working of laws within our comprehension."

But to return to the Zoological wonders of the Upper Amazon,