Though, of course, present results as to the origin and migrations of
genera of mammals will have to be modified owing to new discoveries, I
cannot help thinking that much will remain unaffected, because in all
geographical and geological discoveries the great outlines are soon
reached, the details alone remain to be modified. I also think much of the
geological evidence is now so accordant with, and explanatory of,
Geographical Distribution, that it is prima facie correct in outline.
Nevertheless, such vast masses of new facts will come out in the next few
years that I quite dread the labour of incorporating them in a new edition.

I hope your health is improved; and when, quite at your leisure, you have
waded through my book, I trust you will again let me have a few lines of
friendly criticism and advice.


LETTER 391. TO A.R. WALLACE.
Down, June 17th, 1876.

I have now finished the whole of Volume I., with the same interest and
admiration as before; and I am convinced that my judgment was right and
that it is a memorable book, the basis of all future work on the subject.
I have nothing particular to say, but perhaps you would like to hear my
impressions on two or three points. Nothing has struck me more than the
admirable and convincing manner in which you treat Java. To allude to a
very trifling point, it is capital about the unadorned head of the Argus-
pheasant. (391/1. See "Descent of Man," Edition I., pages 90 and 143, for
drawings of the Argus pheasant and its markings. The ocelli on the wing
feathers were favourite objects of Mr. Darwin, and sometimes formed the
subject of the little lectures which on rare occasions he would give to a
visitor interested in Natural History. In Mr. Wallace's book the meaning