I did not intend to take any public notice of reviews or criticisms of my book on "Geographical Distribution"; Mr. Gill's letter, however, calls for a few remarks. I have first to thank him for pointing out the errors of a previous critic, and also for a list of errata in the account of North American fresh-water fishes. He very truly remarks, that had I been acquainted with ichthyology and its literature these errors might have been avoided; but he has overlooked the fact that I have twice stated (vol. i, p. 101, and vol. ii, p. 168) that the part of my work relating to fishes is, practically, a summary of Dr. Günther's Catalogue. The labour of going through such an extensive work for the purpose of extracting and tabulating summaries of the geographical materials it contains, was very great, and no doubt I have made some errors. Most of those indicated by Mr. Gill depend, however, either on differences of classification and nomenclature, or on additions to North American ichthyology since the date of Dr. Günther's work, and are therefore due to the plan of this part of my book, and not to oversight. Although possessing a tolerable acquaintance with the literature of ornithology, I had found the task of collating and combining the latest information into a uniform system of classification and nomenclature to be one which severely taxed whatever knowledge and literary ability I possessed. To have attempted to do the same thing in a class of animals which I had never studied would, I felt sure, have resulted in great confusion, and have been far less satisfactory and reliable than the course I have adopted. Had I been able to find any work giving a general account of the fishes of temperate North America, I should gladly have availed myself of it, but I do not gather from Mr. Gill's letter that any such work exists; and notwithstanding the great imperfection of the results (in the eyes of a specialist) as regards the fishes of the United States, I still think I exercised a wise discretion in confining myself to the vast mass of materials, classified on a uniform system, which Dr. Günther's Catalogue affords.

     I may here add, that the "24 peculiar genera" mentioned by me are in addition to the "5 peculiar family types"--making together the "29 peculiar genera" referred to in the succeeding paragraph--so that the contradiction alluded to by Mr. Gill is only apparent.

Alfred R. Wallace
Dorking, October 30