It harmonises with the modification of species; and without admitting this awful postulate, the Glacial epoch in the south and tropics does not work in well.

About Atlantis, I doubt whether the Canary Islands are as much more related to the continent as they ought to be, if formerly connected by continuous land.
Hooker, with whom I have formerly discussed the notion of the world or great belts of it having been cooler, though he at first saw great difficulties (and difficulties there are great enough), I think is much inclined to adopt the idea.

With modification of specific forms it explains some wondrous odd facts in distribution.
But I shall never stop if I get on this subject, on which I have been at work, sometimes in triumph, sometimes in despair, for the last month.
LETTER 328.

ASA GRAY TO CHARLES DARWIN.

Received August 20th, 1856.
I enclose you a proof of the last page, that you may see what our flora amounts to.