See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1866
1872

and at that time less differentiated vertebrate 1869 1872
vertebrate 1859 1860 1861
and then less differentiated vertebrate 1866

as with 1869
as in that of 1859 1860 1861 1866
for instance 1872

and only partially 1866 1869 1872
but 1859 1860 1861

still 1869 1872
from other groups, as all would blend together by steps as fine as those between the finest existing varieties, nevertheless 1859 1860
from other groups, as all would blend together by steps as fine as those between existing varieties, nevertheless 1861
from other groups, as all would be blended together by steps as fine as those between existing varieties, nevertheless 1866

with every 1869 1872
Every intermediate link between these eleven genera and their primordial parent, and every intermediate 1859 1860 1861 1866

OMIT 1869 1872
of their descendants, may be supposed to be 1859 1860 1861 1866

not greater than 1869 1872
to be as fine as 1859 1860 1861 1866

almost impossible to do
this
so
without this aid, we can understand the
extra- ordinary
extraordinary
difficulty which naturalists have experienced in describing, without the aid of a diagram, the various affinities which they perceive between the many living and extinct members of the same great natural class.
Extinction, as we have seen in the fourth chapter, has played an important part in defining and widening the intervals between the several groups in each class. We may thus account
even
....
for the distinctness of whole classes from each other— for instance, of birds from all other vertebrate animals— by the belief that many ancient forms of life have been utterly lost, through which the early progenitors of birds were formerly connected with the early progenitors of the other and at that time less differentiated vertebrate classes. There has been
less entire
much less
less complete
extinction of the forms of life which once connected fishes with batrachians. There has been still less
within
in
some
whole
other
classes, as with the Crustacea, for here the most
wonder-fully
wonderfully
diverse forms are still
tied
linked
together by
a
a
long,
long
and only partially
broken,
broken
chains
chain
of affinities. Extinction has only
defined the
separated
groups:
the groups:
it has by no means made them; for if every form which has ever lived on this earth were suddenly to reappear, though it would be quite impossible to give definitions by which each group could be
distinguished
distinguished,
still a natural classification, or at least a natural arrangement, would be possible. We shall see this by turning to the
diagram;
diagram:
the letters, A to L, may represent eleven Silurian genera, some of which have produced large groups of modified
descendants.
descendants,
with every link in each branch and sub-branch OMIT still alive; and the links not greater than those between
existing
the finest
varieties. In this case it would be quite impossible to give
any
....
definition
definitions
by which the