Comparison with 1859 |
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Text in this page (from paragraph 4100, sentence 510, word 29 to paragraph 4100, sentence 600, word 28) is not present in 1859 |
The case most frequently insisted on by palæontologists of the apparently sudden appearance of a whole group of species, is that of the teleostean fishes, low
down down 1859 1860 1861 1866 1869 | down, 1872 |
in in 1859 1860 1861 1866 1869 |
according to Agassiz, in 1872 |
the Chalk period. This group includes the large majority of existing species. ↑2 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | But certain Jurassic and Triassic forms are now commonly admitted to be teleostean; and even some palæozoic forms have thus been classed by one high authority.
If the teleosteans had really appeared suddenly in the northern hemisphere at the commencement of the chalk formation, the fact would have been highly remarkable; but it would not have formed an insuperable difficulty, unless it could likewise have been shown that at the same period the species were suddenly and simultaneously developed in other quarters of the world.
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Lately, Professor Pictet has carried their existence one sub-stage further back; and some palæontologists believe that certain much older fishes, of which the affinities are as yet imperfectly known, are really teleostean. Assuming, however, that the whole of them did appear, as Agassiz believes,
at the commencement of the chalk formation, the fact would certainly be highly remarkable; but I cannot see that it would be an insuperable difficulty on my theory,
unless it could likewise be shown that the species of this group appeared suddenly and simultaneously throughout the world at this same period. It is almost superfluous to remark that hardly any fossil-fish are known from south of the equator; and by running through Pictet's
Palæontology it will be seen that very few species are known from several formations in Europe. Some few families of fish now have a confined range; the teleostean
fish fish 1859 1860 1861 1866 1869 | fishes 1872 |
might formerly have had a similarly confined range, and after having been largely developed in some one sea,
might might 1859 1860 1861 1866 1869 | might 1872 |
have spread widely. Nor have we any right to suppose that the seas of the world have always been so freely open from south to north as they are at present. Even at this day, if the Malay Archipelago were converted into land, the tropical parts of the Indian Ocean would form a large and perfectly enclosed basin, in 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
southern southern 1859 1860 1861 1866 1869 | Southern 1872 |
capes of Africa or Australia, and thus reach other and distant seas. |
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From these
and similar considerations, but chiefly and similar considerations, but chiefly 1859 1860 1861 1866 |
considerations, 1869 1872 |
from our ignorance of the geology of other countries beyond the confines of Europe and the United
States; States; 1859 1860 1861 1866 | States, 1869 1872 |
and from the revolution in our palæontological
ideas on many points, which ideas on many points, which 1859 1860 1861 1866 |
knowledge effected by 1869 1872 |
the discoveries of
even even 1859 1860 1861 1866 | even 1869 1872 |
the last dozen
years years 1859 1860 1861 1866 | years, 1869 1872 |
have effected, have effected, 1859 1860 1861 1866 | have effected, 1869 1872 |
it seems to me to be about as rash
in us in us 1859 1860 1861 1866 | in us 1869 1872 |
to dogmatize on the succession of organic
beings beings 1859 1860 1861 1866 | forms 1869 1872 |
throughout the world, as it would be for a naturalist to land for five minutes on
some one some one 1859 1860 1861 1866 | a 1869 1872 |
barren point in Australia, and then to discuss the number and range of its productions. |
On
On
1859 1860 1861 |
On
1866 1869 1872 |
the
the
1859 1860 1861 |
the
1866 1869 1872 |
sudden
sudden
1859 1860 1861 |
sudden
1866 1869 1872 |
appearance
appearance
1859 1860 1861 |
Appearance
1866 1869 1872 |
of
of
1859 1860 1861 |
of
1866 1869 1872 |
groups
groups
1859 1860 1861 |
Groups
1866 1869 1872 |
of
of
1859 1860 1861 |
of
1866 1869 1872 |
Allied
Allied
1859 1860 |
allied
1861 |
allied
1866 1869 1872 |
Species
Species
1859 1860 1861 |
Species
1866 1869 1872 |
in
in
1859 1860 1861 |
in
1866 1869 1872 |
the
the
1859 1860 1861 |
the
1866 1869 1872 |
lowest
lowest
1859 1860 1861 |
lowest
1866 1869 1872 |
known
known
1859 1860 1861 |
known
1866 1869 1872 |
fossiliferous
fossiliferous
1859 1860 1861 |
Fossiliferous
1866 1869 1872 |
strata
.—
strata
.—
1859 1860 1861 |
Strata
. 1866 1869 1872 |
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There is another and allied difficulty, which is much
graver. graver. 1859 1860 1861 | more serious. 1866 1869 1872 |
I allude to the manner in which
numbers of species numbers of species 1859 1860 1861 1866 |
many species in several 1869 |
species belonging to several 1872 |
of the
same group, same group, 1859 1860 1861 |
same group 1866 |
main divisions of the animal kingdom 1869 1872 |
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