iods alternately wet and dry, and of the
important part which they have played in distribution.

I wrote to Forel (392/3. See Letter 388.), who is always at work
on ants, and told him your views about the dispersal of the blind
coleoptera, and asked him to observe.

I spoke to Hooker about your book, and feel sure that he would like
nothing better than to consider the distribution of plants in relation
to your views; but he seemed to doubt whether he should ever have time.

And now I have done my jottings, and once again congratulate you on
having brought out so grand a work. I have been a little disappointed at
the review in "Nature." (392/4. June 22nd, 1876, pages 165 et seq.)

LETTER 393. A.R. WALLACE TO CHARLES DARWIN. Rosehill, Dorking, July
23rd, 1876.

I should have replied sooner to your last kind and interesting letters,
but they reached me in the midst of my packing previous to removal here,
and I have only just now got my books and papers in a get-at-able state.

And first, many thanks for your close observation in detecting the two
absurd mistakes in the tabular headings.

As to the former greater distinction of the North and South American
faunas, I think I am right. The edentata being proved (as I hold)
to have been mere temporary migrants into North America in the
post-Pliocene epoch, form no part of its Tertiary fauna. Yet in South
America they were so enormously developed in the Pliocene epoch that
we know, if there is any such thing as evolution, etc., that strange
ancestral forms must have preceded them in Miocene times.

Mastodon, on the other hand, represented by one or two species only,
appears to have been a late immigrant into South America from the north.

The immense development of ungulates (in varied families, genera, and
species) in North America during the whole Tertiary epoch is, however,
the great feature which assimilates it to Europe, and contrasts it
with South America. True camels, hosts of hog-like animals, true
rhinoceroses, and hosts of ancestral horses, all bring the North
American [fauna] much nearer to the Old World than it is now. Even the
horse, represented in all South America by Equus only, was probably a
temporary immigrant from the north.

As to extending too far the principle (yours) of the necessity of
comparatively large areas for the development of varied faunas, I may
have done so, but I think not. There is, I think, every probability that
most islands, e