| → in 1859 1860 1861 1866 1869 |
| from its allies, in 1872 |
|
| → from its allies, 1859 1860 1861 1866 1869 |
| OMIT 1872 |
|
| → presently 1869 1872 |
| hereafter, I think, clearly 1859 1860 1861 1866 |
|
| → which is a pachydermatous animal, and the 1859 1860 1861 1866 1869 |
| and 1872 |
|
| → mammals 1859 1860 1861 1866 1869 |
| two orders of mammals 1872 |
|
| ↑ 2 blocks not present in 1859 1860 1861 1866 1869; present in 1872 |
| So is the resemblance between a mouse and a shrew-mouse (Sorex), which belong to different orders; and the still closer resemblance, insisted on by Mr. Mivart, between the mouse and a small marsupial animal (Antechinus) of Australia.
These latter resemblances may be accounted for, as it seems to me, by adaptation for similarly active movements through thickets and herbage, together with concealment from enemies.
|
|
|
We can understand why a species or a group of species may
→in
several of its most important characteristics,
→from its allies,
and yet be safely classed with them. This may be safely done, and is often done, as long as a sufficient number of characters, let them be ever so unimportant, betrays the hidden bond of community of descent. Let two forms have not a single character in common,
if these extreme forms are connected together by a chain of intermediate
we may at once infer their community of descent, and we put them all into the same class. As we find organs of high physiological importance— those which serve to preserve life under the most diverse conditions of existence— are generally the most constant, we attach especial value to them; but if these same organs, in another group or section of a group, are found to differ much, we at once value them less in our classification. We shall
→presently
see why embryological characters are of such high classificatory importance. Geographical distribution may sometimes be brought usefully into play in classing large
genera, because all the species of the same genus, inhabiting any distinct and isolated region,
in all probability descended from the same parents. |
|
Analogical
|
| We can understand, on
views, the very important distinction between real affinities and analogical or adaptive resemblances. Lamarck first called attention to this
and he has been ably followed by Macleay and others. The
in the shape of the body and in the fin-like anterior
between
→which is a pachydermatous animal, and the
and between
these
→mammals
and fishes,
analogical. ↑ Amongst insects there are innumerable
thus Linnæus, misled by external appearances, actually classed an
|
