Origin of Species Variorum

→ American 1859 1860 1861 1866

belonging to American 1869 1872

→ given 1859 1860 1861

allowed 1866 1872

allowed many of 1869

→ general forms to the whole 1859 1860 1861

fresh-water productions to prevail throughout the 1866

species to prevail through large portions of the 1869

forms to prevail throughout large portions of the 1872

→ the 1859 1860 1866 1869 1872

some of the 1861

→ blind 1859 1860 1861

character of most of the blind 1866 1869 1872

→ closely-allied 1860 1861 1866

closely allied or 1859 1869 1872

→ showing, in accordance with the foregoing view, that at some former period there has been intercommunication or migration between the two regions. 1859 1860 1861

showing, in accordance with the foregoing views, that at some former period there has been intercommunication or migration between the two regions. 1866

and wherever many closely-allied species occur, there will be found many forms which some naturalists rank as distinct species, and others as mere varieties; these doubtful forms showing us the steps in the progress of modification. 1869 1872

→ under different physical conditions, 1859 1860 1861 1866

OMIT 1869 1872

→ allied to it, 1859 1860 1861 1866

OMIT 1869 1872

→ it would be difficult to prove it. 1859 1860 1861 1866 1869

difficult of proof. 1872

→ it, if we compare 1859 1860 1861 1866

the same rule in 1869 1872

→ fresh-water productions, in which so many genera 1859 1860 1861 1866

of the inhabitants of fresh water, for many of the genera in the most distinct classes 1869 1872

all

strictly of

strictly

of strictly

→American

forms;

forms,

and it is obvious that a mountain, as it became slowly upheaved, would

~~naturally~~

naturally

be colonised from the surrounding lowlands. So it is with the inhabitants of lakes and marshes, excepting in so far

that

great facility of transport has →given the same →general forms to the whole world. We see this same principle in →the →blind animals inhabiting the caves of America and of Europe. Other analogous facts could be given.

And it

will, I believe, be

~~universally~~

universally

found

universally

~~to be~~

to be

true, that wherever in two regions, let them be ever so distant, many →closely-allied

representative

or representative

species occur, there will likewise be found some identical

species;

species,

→showing, in accordance with the foregoing view, that at some former period there has been intercommunication or migration between the two regions. And wherever many closely-allied species occur, there will be found many forms which some naturalists rank as distinct species, and some as

mere varieties;

varieties;

these doubtful forms showing us the steps in the

progress

process

of modification.

The

This

relation between the power and extent of migration

in a

in certain

of a

species, either at the present

~~time~~

time

or at some former

period,

period

→under different physical conditions, and the existence at remote points of the world of

allied

closely-allied

other

species,

species

→allied to it, is shown in another and more general way. Mr. Gould remarked to me long ago, that in those genera of birds which range over the world, many of the species have very wide ranges. I can hardly doubt that this rule is generally true, though →it would be difficult to prove it. Amongst mammals, we see it strikingly displayed in Bats, and in a lesser degree in the Felidæ and Canidæ. We see →it, if we compare the distribution of butterflies and beetles. So it is with most →fresh-water productions, in which so many genera range over the world, and many

of the

individual

species have