| → considerations, 1869 1872 |
| and similar considerations, but chiefly 1859 1860 1861 1866 |
|
| → knowledge effected by 1869 1872 |
| ideas on many points, which 1859 1860 1861 1866 |
|
| → many species in several 1869 |
| numbers of species 1859 1860 1861 1866 |
| species belonging to several 1872 |
|
| → main divisions of the animal kingdom 1869 1872 |
| same group, 1859 1860 1861 |
| same group 1866 |
|
| → Silurian trilobites are 1869 |
| Silurian trilobites have 1859 1860 1861 1866 |
| Cambrian and Silurian trilobites are 1872 |
|
|
which any great group of marine animals might be multiplied; and here they would remain confined, until some of the species became adapted to a cooler climate, and were enabled to double the
capes of Africa or Australia, and thus reach other and distant seas. |
|
| From these
→considerations,
from our ignorance of the geology of other countries beyond the confines of Europe and the United
and from the revolution in our palæontological
→knowledge effected by
the discoveries of
the last dozen
it seems to me to be about as rash
to dogmatize on the succession of organic
throughout the world, as it would be for a naturalist to land for five minutes on
barren point in Australia, and then to discuss the number and range of its productions. |
|
|
| There is another and allied difficulty, which is much
I allude to the manner in which
→many species in several
of the
→main divisions of the animal kingdom
suddenly appear in the lowest known fossiliferous rocks. Most of the arguments which have convinced me that all the existing species of the same group
descended from
progenitor, apply with
equal force to the earliest known species. For instance,
cannot
that all the
→Silurian trilobites are
descended from some one crustacean, which must have lived long before the
age, and which probably differed greatly from any known animal. Some of the most ancient
animals, as the Nautilus, Lingula,
do not differ much from living species; and it cannot on
theory be supposed, that these old species were the progenitors of all the species
|
