My dear Wallace,—­I have been able to read rather more quickly of late and have finished your book.  I have not much to say.  Your careful account of the temperate parts of South America interested me much, and all the more from knowing something of the country.  I like also much the general remarks towards the end of the volume on the land molluscs.  Now for a few criticisms.

P. 122:[107] I am surprised at your saying that “during the whole Tertiary period North America was zoologically far more strongly contrasted with South America than it is now.”  But we know hardly anything of the latter except during the Pliocene period, and then the mastodon, horse, several great Dentata, etc. etc., were common to the North and South.  If you are right I erred greatly in my Journal, where I insisted on the former close connection between the two.

P. 252, and elsewhere:  I agree thoroughly with the general principle that a great area with many competing forms is necessary for much and high development; but do you not extend this principle too far—­I should say much too far, considering how often several species of the same genus have been developed on very small islands?

P. 265:  You say that the Sittidae extend to Madagascar, but there is no number in the tabular heading.[108]

P. 359:  Rhinochetus is entered in the tabular heading under No. 3 of the Neotropical sub-regions.[109]

Reviewers think it necessary to find some fault, and if I were to review you, the sole point which I should blame is your not giving very numerous references.  These would save whoever follows you great labour.  Occasionally I wished myself to know the authority for certain statements, and whether you or somebody else had originated certain subordinate views.  Take the case of a man who had collected largely on some island, for instance St. Helena, and who wished to work out the geographical relations of his collection; he would, I think, feel very blank at not finding in your work precise references to all that had been written on St. Helena.  I hope you will not think me a confoundedly disagreeable fellow.

I may mention a capital essay which I received a few mouths ago from Axel Blytt[110] on the distribution of the plants of Scandinavia; showing the high probability of there having been secular periods alternately wet and dry; and of the important part which they have played in distribution.

I wrote to Forel, who is always at work on ants, and told him of 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[111]—­My dear Wallace, yours sincerely,