confined to some one spot. Most marine animals have a wide range; and we have seen that with plants it is those which have the widest range, that oftenest present varieties; so that
with shells and other marine animals, it is probably
those which have
had the widest range, far exceeding the limits of the known geological formations of Europe, which
have oftenest given rise, first to local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any one
geological formation. ↑| 1 blocks not present in 1859 1860 1861; present in 1866 1869 1872 | | It is a more important consideration, clearly
leading to the same result, as lately insisted on by Dr. Falconer, namely, that the periods
during which species have been undergoing
modification, though very
long as measured by years, have probably been
short in comparison with the periods
during which these same species
remained without undergoing any change.
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It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate varieties
and thus proved to be the same species, until many specimens have been
collected from many places; and in the case of
fossil species this could
rarely be effected by palæontologists. We shall, perhaps, best perceive the improbability of our being enabled to connect species by numerous,
fine, intermediate,
fossil links, by asking
CHAP. IX. GEOLOGICAL RECORD. | CHAP. IX. GEOLOGICAL RECORD. 1859 |
| OMIT 1860 1861 1866 1869 1872 |
| 4 blocks not present in 1859 1860; present in 1861 1866 1869 1872 | | It has been asserted over and over again, by writers who believe in the immutability of species, that geology has
yielded
no linking forms.
This assertion
is entirely
erroneous.
As Mr.
Lubbock has recently
remarked, "Every
species is a link between other allied forms." We clearly see this if
we take a genus having a score of recent and extinct species
and destroy four-fifths of them;
for in this case
no one will
doubt
that the remainder will stand much more distinct from each other.
If the extreme forms in the genus happen to have been thus destroyed, the genus itself in most cases
will stand more distinct from other allied genera.
|
| 2 blocks not present in 1859 1860 1872; present in 1861 1866 1869 | | The camel and the pig, or the horse and the tapir, are now obviously very distinct forms; but if we add the several fossil quadrupeds which have already been discovered to the families including the camel and pig, these forms become joined by links not extremely wide apart.
The chain of linking forms does not, however, in these cases, or in any case, run straight from the one living form to the other, but takes a circuitous sweep through the forms which lived during long past
ages.
|
| 2 blocks not present in 1859 1860; present in 1861 1866 1869 1872 | | What geological research has not revealed
is the former existence of infinitely numerous gradations, as fine as existing varieties, connecting all known
species.
And
this not having been effected by geology is the most obvious of the many objections which may be urged
against my views.
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