. Barrande, also, shows that there is a striking
general parallelism in the successive Silurian deposits of Bohemia and
Scandinavia; nevertheless he finds a surprising amount of difference in
the species. If the several formations in these regions have not been
deposited during the same exact periods--a formation in one region often
corresponding with a blank interval in the other--and if in both regions
the species have gone on slowly changing during the accumulation of the
several formations and during the long intervals of time between them;
in this case the several formations in the two regions could be arranged
in the same order, in accordance with the general succession of the
forms of life, and the order would falsely appear to be strictly
parallel; nevertheless the species would not all be the same in the
apparently corresponding stages in the two regions.

ON THE AFFINITIES OF EXTINCT SPECIES TO EACH OTHER, AND TO LIVING FORMS.

Let us now look to the mutual affinities of extinct and living species.
All fall into a few grand classes; and this fact is at once explained on
the principle of descent. The more ancient any form is, the more, as a
general rule, it differs from living forms. But, as Buckland long ago
remarked, extinct species can all be classed either in still existing
groups, or between them. That the extinct forms of life help to fill
up the intervals between existing genera, families, and orders, is
certainly true; but as this statement has often been ignored or even
denied, it may be well to make some remarks on this subject, and to give
some instances. If we confine our attention either to the living or to
the extinct species of the same class, the series is far less perfect
than if we combine both into one general system. In the writings of
Professor Owen we continually meet with the expression of generalised
forms, as applied to extinct animals; and in the writings of Agassiz, of
prophetic or synthetic types; and these terms imply that such forms
are, in fact, intermediate or connecting links. Another distinguished
palaeontologist, M. Gaudry, has shown in the most striking manner that
many of the fossil mammals discovered by him in Attica serve to break
down the intervals between existing genera. Cuvier ranked the Ruminants
and Pachyderms as two of the most distinct orders of mammals; but so
many fossil links have been disentombed that Owen has had to alter the
whole classification, and has plac