| → vertebrate 1859 1860 1861 |
| and then less differentiated vertebrate 1866 |
| and at that time less differentiated vertebrate 1869 1872 |
|
| → as in that of 1859 1860 1861 1866 |
| as with 1869 |
| for instance 1872 |
|
| → but 1859 1860 1861 |
| and only partially 1866 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 |
| still 1869 1872 |
|
| → Every intermediate link between these eleven genera and their primordial parent, and every intermediate 1859 1860 1861 1866 |
| with every 1869 1872 |
|
|
of any ancient and noble
even by the aid of a genealogical tree, and almost impossible to do
without this aid, we can understand the
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
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
→vertebrate
classes. There has been
extinction of the forms of life which once connected fishes with batrachians. There has been still less
some
classes,
→as in that of
the Crustacea, for here the most
diverse forms are still
together by
→but
of affinities. Extinction has only
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
→from other groups, as all would blend together by steps as fine as those between the finest existing varieties, nevertheless
a natural classification, or at least a natural arrangement, would be possible. We shall see this by turning to the
the letters, A to L, may represent eleven Silurian genera, some of which have produced large groups of modified
→Every intermediate link between these eleven genera and their primordial parent, and every intermediate
|
