My dear Darwin

I have been intending to write to you for some weeks to call your attention to what seems to me a striking confirmation (or at all events a support) of my views of the land migration of plants from mountain to mountain.¹ In Nature of Dec. 9 p. 126 Mr. Baker of Kew describes a number of the alpine plants of Madagascar as being identical species with some found on the Mt^ns. of Abyssinia, the Cameroons, & other African mountains.² Now if there is one thing more clear than another it is that Madagascar has been separated from Africa since the Miocene (probably the early Miocene) epoch— These plants must therefore have reached the island, either, since then, in which case they certainly must have passed through the air for long distances,— or at the time of the union. But the Miocene and Eocene periods were certainly warm, & these Alpine plants could hardly have migrated over tropical forest lands, while it is very improbable that if they had been isolated at so remote a period exposed to such distinct climatal and organic environments as in Madagascar and Abyssinia, they would have in both places retained their specific characters unchanged. The presumption is, therefore, that they are comparatively recent immigrants, & if so must have passed across the sea from mountain to mountain,— for the richness & speciality of the Madagascar forest-vegetation renders it certain that no recent glacial epoch has seriously affected that island.

Hoping that you are in good health & wishing you the compliments of the season, | I remain | Yours very faithfully | Alfred R. Wallace.

Charles Darwin F.R.S