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, believes, 1859 1860 1861 | maintains, 1866 1869 |
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, difficulty on my theory, 1859 1860 1861 1866 |
objection to these views, 1869 |
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 Pictet's 1859 1860 1861 1866 1872 | Pictets 1869 |
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. |
|
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
|