| → of the bizcacha to Marsupials 1859 1860 1861 1866 |
| OMIT 1869 1872 |
|
| → are due on my theory 1859 1860 1861 1866 |
| must be due in accordance with our view 1869 1872 |
|
| → in common. 1859 1860 1861 1866 |
| from a common progenitor. 1869 1872 |
|
| → have had a character in some degree intermediate 1859 1860 1861 |
| naturally have been more or less intermediate in character 1866 1869 1872 |
|
|
belonging to one group of animals exhibits an affinity to a quite distinct group, this affinity in most cases is general and not special: thus, according to Mr. Waterhouse, of all Rodents, the bizcacha is most nearly related to Marsupials; but in the points in which it approaches this order, its relations are general, and not to any one marsupial species more than to another. As
points of affinity
→of the bizcacha to Marsupials
are believed to be real and not merely adaptive, they
→are due on my theory
to inheritance
→in common. Therefore we must suppose either that all Rodents, including the
branched off from some
ancient Marsupial, which will
→have had a character in some degree intermediate
with respect to all existing Marsupials; or that both Rodents and Marsupials branched off from a common progenitor, and that both groups have since undergone much modification in divergent directions. On either view we
suppose that the bizcacha has retained, by inheritance, more of the
of its ancient progenitor than have other Rodents; and therefore it will not be specially related to any one existing Marsupial, but indirectly to all or nearly all Marsupials, from having partially retained the character of their common progenitor, or of
early member of the group. On the other hand, of all Marsupials, as Mr. Waterhouse has remarked, the
resembles most nearly, not any one species, but the general order of Rodents. In this case, however, it may be strongly suspected that the resemblance is only analogical, owing to the
having become adapted to habits like those of a Rodent. The elder De Candolle has made nearly similar observations on the general nature of the affinities of distinct
of plants. |
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| On the principle of the multiplication and gradual divergence in character of the species descended from
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