By the way, I heard lately from Wollaston, who told me that he had just received eminently Madeira and Canary Island insect forms from the Cape of Good Hope, to which trifling distance, if he is logical, he will have to extend his Atlantis! I have just received your letter, and am very much pleased that you approve. But I am utterly disgusted and ashamed about the dingo. I cannot think how I could have misunderstood the paper so grossly. I hope I have not blundered likewise in its co-existence with extinct species: what horrid blundering! I am grieved to hear that you think I must work in the notes in the text; but you are so much better a judge that I will obey. I am sorry that you had the trouble of returning the Dog MS., which I suppose I shall receive to-morrow. I mean to give good woodcuts of all the chief races of pigeons. (112/2. "The Variation of Animals and Plants under Domestication," 1868.) Except the C. oenas (112/3. The Columba oenas of Europe roosts on trees and builds its nest in holes, either in trees or the ground ("Var. of Animals," Volume I., page 183).) (which is partly, indeed almost entirely, a wood pigeon), there is no other rock pigeon with which our domestic pigeon would cross--that is, if several exceedingly close geographical races of C. livia, which hardly any ornithologist looks at as true species, be all grouped under C. livia. (112/4. Columba livia, the Rock-pigeon. "We may conclude with confidence that all the domestic races, notwithstanding their great amount of difference, are descended from the Columba livia, including under this name certain wild races" (op. cit., Volume I., page 223).) I am writing higgledy-piggledy, as I re-read your letter. I thought that my letter had been much wilder than yours. I quite feel the comfort of writing when one may "alter one's speculations the day after." It is beyond my knowledge to weigh ranks of birds and monotremes; in the respiratory and circulatory system and muscular energy I believe birds are ahead of all mammals. I knew that you must have known about New Guinea; but in writing to you I never make myself civil! After treating some half-dozen or dozen domestic animals in the same manner as I treat dogs, I intended to have a chapter of conclusions. But Heaven knows when I shall finish: I get on very slowly. You would be surprised how long it took me to pick out what seemed useful about dogs out of multitudes of details. I see the force of your remark about more isolated races of man in old times, and therefore more in number. It seems to me difficult to weigh probabilities. Perhaps so, if you refer to very slight differences in the races: to make great differences much time would be required, and then, even at the earliest period I should have expected one race to have spread, conquered, and exterminated the others.