| → by 1859 1860 1861 1866 1869 |
| as at present by 1872 |
|
| → but such richness in species, as I find after some investigation, does not commonly fall to the lot of aberrant genera. 1859 1860 1861 1866 |
| or by one or two. 1869 |
| or by two or three. 1872 |
|
| → failing groups 1859 1860 1861 1866 |
| forms which have been 1869 1872 |
|
| → preserved by some unusual coincidence of favourable circumstances. 1859 1860 1861 1866 |
| still preserved under unusually favourable conditions. 1869 1872 |
|
| → 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 |
|
| → naturally have been more or less intermediate in character 1866 1869 1872 |
| have had a character in some degree intermediate 1859 1860 1861 |
|
|
each other, which again implies extinction. The genera Ornithorhynchus and Lepidosiren, for example, would not have been less aberrant had each been represented by a dozen
instead of
→by
a single
→but such richness in species, as I find after some investigation, does not commonly fall to the lot of aberrant genera. We can, I think, account for this fact only by looking at aberrant
as
→failing groups
conquered by more successful competitors, with a few members
→preserved by some unusual coincidence of favourable circumstances.
|
|
| Mr. Waterhouse has remarked that, when a member 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
→naturally have been more or less intermediate in character
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
|
