Darwin Online
Publications
Manuscripts
Biography
Media
About Us
Advanced search

See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1861
1866
1869
1872

→ a dozen characters, in this case the genera, 1859 1860 1861
half a dozen important characters, then the families which existed 1866
→ differ 1859 1860 1861
certainly have differed from each other 1866
→ at 1859 1860 1861
they would at 1866
→ character from the 1859 1860 1861
a less degree from their 1866
→ some slight 1859 1860 1861 1866 1869
a greater or less 1872
→ seem to me 1859 1860 1861 1866
are 1869 1872
other by →a dozen characters, in this case the genera, at the
early
early
period marked
VI.
VI.,
would →differ by a
less
lesser
number of characters; for →at this early stage of descent
they
they
have
not
not
diverged in →character from the common
progenitor.
progenitor
of
of
the
the
order,
order,
nearly
nearly
so
so
much
much
as
as
they
they
sub- sequently
subsequently
subsequently
diverged.
diverged.
Thus it comes that ancient and extinct genera are often in →some slight degree intermediate in
cha- racter
character
between their modified descendants, or between their collateral relations.
Under
In
nature the
process
case
will be far more complicated than is represented in the diagram; for the groups will have been more
numerous;
numerous,
they will have endured for extremely unequal lengths of time, and will have been modified in various degrees. As we possess only the last volume of the geological record, and that in a very broken condition, we have no right to expect, except in
very
very
rare cases, to fill up
the wide
wide
intervals in the natural system, and thus
to unite
unite
distinct families or orders. All that we have a right to
expect
expect,
is,
is
that those
groups
groups,
which
have,
have
within known geological
periods,
periods
undergone much modification, should in the older formations make some slight approach to each other; so that the older members should differ less from each other in some of their characters than do the existing members of the same groups; and this by the concurrent evidence of our best palæontologists
is
seems
frequently
to be
to be
the case.
Thus, on the theory of descent with modification, the main facts with respect to the mutual affinities of the extinct forms of life to each other and to living forms, →seem to me explained in a satisfactory manner. And they are wholly inexplicable on any other view.
On this same theory, it is evident that the fauna
during
of
any
one great
great
period in the earth's history will be
inter- mediate
intermediate
in general character between that which preceded and that which succeeded it.
Thus
Thus,
the species which lived at the sixth great stage of descent in the