But supposing for an
instant, in this and other such cases, that the record of the first
appearance and disappearance of the species was complete, which is far from
the case, we have no reason to believe that forms successively produced
necessarily endure for corresponding lengths of time. A very ancient form
may occasionally have lasted much longer than a form elsewhere subsequently
produced, especially in the case of terrestrial productions inhabiting
separated districts. To compare small things with great; if the principal
living and extinct races of the domestic pigeon were arranged in serial
affinity, this arrangement would not closely accord with the order in time
of their production, and even less with the order of their disappearance;
for the parent rock-pigeon still lives; and many varieties between the
rock-pigeon and the carrier have become extinct; and carriers which are
extreme in the important character of length of beak originated earlier
than short-beaked tumblers, which are at the opposite end of the series in
this respect.
Closely connected with the statement, that the organic remains from an
intermediate formation are in some degree intermediate in character, is the
fact, insisted on by all palaeontologists, that fossils from two
consecutive formations are far more closely related to each other, than are
the fossils from two remote formations. Pictet gives as a well-known
instance, the general resemblance of the organic remains from the several
stages of the Chalk formation, though the species are distinct in each
stage.
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