| Comparison with 1861 |
|
|
old
and intermediate parent-forms having occasionally
transmitted to the present day descendants but little modified, will give to us
our so-called osculant or aberrant groups. The more aberrant any form is, the greater must be the number of connecting forms which on my theory
have been exterminated and utterly lost. And we have some evidence of aberrant forms
having suffered severely from extinction, for they are generally
represented by extremely few species; and such species as do occur are generally very distinct from 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 species
instead of by
a single one;
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 forms
as failing groups
conquered by more successful competitors, with a few members preserved by some unusual coincidence of favourable circumstances.
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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 the
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
biz- cacha, | biz- cacha, 1861 | | bizcacha, 1859 1860 1866 1869 1872 |
|
old | old 1859 1860 1861 1866 1872 |
| of these old 1869 |
| parent-forms having occasionally 1859 1860 1861 1866 |
| forms having 1869 |
| forms have 1872 |
| will give to us 1859 1860 1861 1866 |
| constitute 1869 |
| these constitute 1872 |
| groups. 1859 1860 1861 1866 | | species. 1869 1872 |
| on my theory 1859 1860 1861 1866 |
| OMIT 1869 1872 |
| forms 1859 1860 1861 1866 | | groups 1869 1872 |
| generally 1859 1860 1861 1866 | | almost always 1869 1872 |
| species 1859 1860 1861 1866 1869 | | species, 1872 |
| by 1859 1860 1861 1866 1869 |
| as at present by 1872 |
| one; 1859 1860 1861 1866 | | one, 1869 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 |
| forms 1859 1860 1861 1866 | | groups 1869 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 |
|
|
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
the | the 1859 1860 1861 1866 1869 | | these 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 |
| bizcacha, 1859 1860 1866 1869 1872 | | biz- cacha, 1861 |
| very 1859 1860 1861 | very 1866 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 |
|
