Origin of Species Variorum

→ difficulty on my theory, 1859 1860 1861 1866

objection to these views, 1869

→ and similar considerations, but chiefly 1859 1860 1861 1866

considerations, 1869 1872

→ ideas on many points, which 1859 1860 1861 1866

knowledge effected by 1869 1872

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

maintains,

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

Pictets

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

fishes

fish

might formerly have had a similarly confined range, and after having been largely developed in some one sea,

~~might~~

might

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

capes of Africa or Australia, and thus reach other and distant seas.

From these →and similar considerations, but chiefly from our ignorance of the geology of other countries beyond the confines of Europe and the United

States,

States;

and from the revolution in our palæontological →ideas on many points, which the discoveries of

~~even~~

even

the last dozen

years,

years

~~have effected,~~

have effected,

it seems to me to be about as rash

~~in us~~

in us

to dogmatize on the succession of organic