varieties; so that
with shells and other marine animals, it is
probably probably 1859 1860 |
highly probable that 1861 1866 |
probable 1869 1872 |
those which have
had the widest range, far exceeding the limits of the known geological formations of Europe,
which which 1859 1860 | which 1861 1866 1869 1872 |
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 one 1859 1860 1866 1869 1872 | ony 1861 |
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.
|
|
It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate
varieties varieties 1859 1860 | varieties, 1861 1866 1869 1872 |
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, numerous, 1859 1860 1872 | numerous 1861 1866 1869 |
fine,
intermediate, intermediate, 1859 1860 1872 | intermediate 1861 1866 1869 |
fossil links, by asking
CHAP. IX. GEOLOGICAL RECORD. CHAP. IX. GEOLOGICAL RECORD. 1859 |
OMIT 1860 1861 1866 1869 1872 |
ourselves ourselves 1859 1860 1869 1872 | our-selves 1861 1866 |
whether, for instance, geologists at some future period will be able to
prove, prove, 1859 1860 | prove 1861 1866 1869 1872 |
that our different breeds of cattle, sheep, horses, and dogs have
descended from a single stock or from several aboriginal stocks; or, again, whether certain sea-shells inhabiting the shores of North America, which are ranked by some conchologists as distinct species from their European representatives, and by other conchologists as only
varieties, are really
varieties varieties 1859 1860 | varieties, 1861 1866 1869 1872 |
or are, as it is called, specifically distinct. This could be effected only by the future geologist
discovering in a fossil state numerous intermediate gradations;
and such success
seems to me seems to me 1859 1860 |
is 1861 1866 1869 1872 |
improbable in the highest degree. |