→ the 1859 1860 1861 1866 1869 |
or groups, the 1872 |
|
→ I apprehend that 1859 1860 1861 1866 |
OMIT 1869 1872 |
|
→ would have to 1859 1860 1861 1866 |
certainly 1869 1872 |
|
→ from each other 1859 1860 1861 1866 |
OMIT 1869 1872 |
|
→ of the same two groups would be distinguished 1859 1860 1861 1866 |
are separated 1869 1872 |
|
→ quite distinct, at that period made some small 1859 1860 1861 1866 |
quite distinct, made at that period a somewhat nearer 1869 |
made a somewhat nearer 1872 |
|
→ other. 1859 1860 1861 1866 1869 |
other than they now do. 1872 |
|
→ represent 1859 1860 1861 1866 1869 |
in italics represent 1872 |
|
meant that an extinct form is directly intermediate in all its characters between two living
→the
objection is
valid. But
→I apprehend that
in a
natural classification many fossil species
→would have to
stand between living species, and some extinct genera between living genera, even between genera belonging to distinct families. The most common case, especially with respect to very distinct groups, such as fish and reptiles, seems to be,
supposing them to be distinguished at the present day
→from each other
by a
characters, the ancient members
→of the same two groups would be distinguished
by a somewhat lesser number of
so that the two
formerly
→quite distinct, at that period made some small
approach to each
→other.
|
|
It is a common belief that the more ancient a form is, by so much the more it tends to connect by some of its characters groups now widely separated from each other. This remark no doubt must be restricted to those groups which have undergone much change in the course of geological ages; and it would be difficult to prove the truth of the proposition, for every now and then even a living animal, as the Lepidosiren, is
having affinities directed towards very distinct groups. Yet if we compare the older Reptiles and Batrachians, the older Fish, the older Cephalopods, and the eocene Mammals, with the more recent members of the same classes, we must admit that there is
truth in the remark. |
|
Let us see how far these several facts and inferences accord with the theory of descent with modification. As the subject is somewhat complex, I must request the reader to turn to the diagram in the fourth chapter. We may suppose that the numbered letters
→represent
|