| → past and present distribution. 1859 1860 1861 1866 1869 |
| organic beings. 1872 |
|
| → have left behind them 1859 1860 1861 1866 |
| which formerly lived 1869 1872 |
|
| → the 1859 1860 1861 1866 |
| have left behind them the 1869 1872 |
|
| → have descended from 1859 1860 1861 |
| are the descendants of 1866 1869 1872 |
|
| → constituting the six 1859 1860 1861 |
| which constitute the several species of the 1866 1869 |
| which constitute the 1872 |
|
| → genera. 1859 1860 1861 |
| genera; 1866 1869 |
| genera containing the several species; 1872 |
|
| → the 1859 1860 1861 |
| each of the 1866 |
| each 1869 1872 |
|
| → genera have all 1859 1860 1861 |
| genera having 1866 |
| genus having 1869 1872 |
|
| → which would probably 1859 1860 1861 |
| and this probably would 1866 |
| and this probably will 1869 |
| and this will 1872 |
|
|
more dominant forms, and there will be nothing immutable in the
of
→past and present distribution.
|
|
| It may be asked in ridicule, whether I suppose that the megatherium and other allied huge
→have left behind them
in South
→the
sloth, armadillo, and anteater, as their degenerate descendants. This cannot for an instant be admitted. These huge animals have become wholly extinct, and have left no progeny. But in the caves of Brazil, there are many extinct species which are closely allied in size and in
characters to the species still living in South America; and some of these fossils may
the actual progenitors of
species. It must not be forgotten that, on
theory, all the species of the same genus
→have descended from
some one species; so
if six genera, each having eight species, be found in one geological formation, and in
succeeding formation there be six other allied or representative genera
the same number of species, then we may conclude that
one species of each of the
older genera has left modified descendants,
→constituting the six
new
→genera.
other seven species of
→the
old
→genera have all
died out and
left no progeny. Or,
→which would probably
be a far commoner case, two or three species
or three
of the six older genera will
the parents of the
new
the other
species and the other
having become utterly extinct. In failing orders, with the genera and species decreasing in
as
is the case
the Edentata of South America, still fewer genera and species will
modified blood-descendants. |
|
|
| I
|
