See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1861
1866
1869
1872

thick 1859 1860
rich in fossils and thick 1861 1866
rich in fossil species of very many kinds and thick 1869
rich in fossil species of many kinds, and thick 1872

the 1859 1860
most of our 1861 1866 1869 1872

local. 1859 1860 1861
local; and lastly, although each species must have passed through numerous transitional stages, it is probable that the periods, during which each underwent modification, though many and long as measured by years, have been short in comparison with the periods during which each remained in an unchanged condition. 1866 1869 1872

must have tended to make the geological record extremely imperfect, and 1859 1860
must have made the geological record extremely imperfect, and 1861
OMIT 1866 1869 1872

not find 1859 1860
find 1861 1866
find many links— we do not find 1869 1872

interminable 1859 1860 1869 1872
many links between the members of the same group— we do not find interminable 1861
many links between the species of the same group— we do not find interminable 1866

1 blocks not present in 1859 1860 1861; present in 1866 1869 1872
It should also be constantly borne in mind that any linking varieties between two or more forms, which might be found, would be ranked, unless the whole chain could be perfectly restored, as so many new and distinct species; for it is not pretended that we have any sure criterion by which species and varieties can be discriminated.

only certain classes of organic beings have been largely preserved in a fossil state; that the number both of specimens and of species, preserved in our museums, is absolutely as nothing compared with the
incalculable
incalculable
number of generations which must have passed away even during a single formation; that, owing to subsidence being
almost necessary
necessary
for the accumulation of
fossiliferous
fossiliferous
deposits thick enough to
outlast
resist
future degradation,
great
enormous
intervals of time
must have
have
elapsed between the successive formations; that there has probably been more extinction during the periods of subsidence, and more variation during the periods of elevation, and during the latter the record will have been least perfectly kept; that each single formation has not been continuously deposited; that the duration of each formation is,
probably,
perhaps,
short compared with the average duration of specific forms; that migration has played an important part in the first appearance of new forms in any one area and formation; that widely ranging species are those which have varied
most
most,
frequently, and
and
have oftenest given rise to new species;
and
and
that varieties have at first
often
often
been local.
All
All
These
these
causes,
causes
taken conjointly, must have tended to make the geological record extremely imperfect, and will to a large extent explain
why— though
why
we do not find interminable varieties, connecting together all
the
the
extinct and existing forms
of life
of life
by the finest graduated steps.
He who rejects
this
these
view
views
of
on
the
imperfection
nature
of the geological record, will rightly reject
the
my
whole theory. For he may ask in vain where are the numberless transitional links which must formerly have connected the closely allied or representative species, found in the
successive
several
stages of the same great
formation?
formation.
He may disbelieve in the
immense
enormous
intervals of time which
must have
have
elapsed between our consecutive formations; he