| → hereafter, I think, clearly 1859 1860 1861 1866 |
| presently 1869 1872 |
|
| → 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.
|
|
| → thickened stems 1859 1860 1861 1866 1869 |
| strikingly similar shape 1872 |
|
| → common and 1859 1860 1861 1866 1869 |
| body in the improved breeds of the Chinese and common pig, which are descended from distinct species; and in the similarly thickened stems of the common and specifically distinct 1872 |
|
| → very distinct animals. 1859 1860 1861 1866 |
| widely distinct animals. 1869 |
|
widely different animals.
1872 |
|
|
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
→hereafter, I think, clearly
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 homopterous insect as a moth. We see something of the same kind even
our domestic varieties, as in the
→thickened stems
of the
→common and
turnip. The resemblance
the greyhound and
is hardly more fanciful than the analogies which have been drawn by some authors between
→very distinct animals. On
view of characters being of real importance for classification, only in so far as they reveal descent, we can clearly understand why analogical or
|
