My dear Sir

You were so kind as to say that I might trouble you occasionally for information. There is now a point on which I am very curious, & which I think I could make out from your Memoir,² but, as I once said before, it is incomparably safer not to infer but to quote direct opinion of author.— Sir J. Richardson says the Fish of the cooler temperate parts of the S. Hemisphere present a much stronger analogy to the fish of the same latitudes in the North, than do the strictly Arctic forms to the Antarctic.³

Now I sh^d. very much like to know how this is with Crustaceans.—⁴ I have quoted your remarks on the relation of the N. Zealand Crust. to those at these Antipodes;⁵ but can you tell me how it is with those further south. I fear that there are hardly materials.— Cape Horn may throw some light, but it is hardly far enough south: I think, as far as I can remember, very few Crust. are known from the S. Shetland or icy regions.— But if you will give me a sentence on Crustacea, in relation to Sir J. Richardson’s remark, I sh^d be particularly obliged.—⁶

When I shall publish my Book, Heaven only knows, for it daily grows on me; but I do some work every day; but my day’s work, from ill-health is ridiculously short.— I am sorry that I have no scientific news to communicate, for I have left home very seldom of late owing to my health having been worse than usual. The most interesting discovery, I think, made for some years, has been the astonishing find of Mammalian remains in the Purbeck beds;⁷ I have seen at D^r. Falconer’s many of the specimens—⁸ They give one an astonishing idea of the richness of the Fauna at that period. Lyell, as you may suppose is delighted. I never saw anything more curious than the manner in which the Plagyoulax (or some such name) connects the living Hypsiprimnus & the Triassic mammifers, about which the doubts formerly held must now be given up; for it must assuredly have been a Mammifer.—⁹

Some small & very highly organised Lizards in same bed are, I think, even more interesting than the Mammalian remains.— This discovery has made a deep impression on some of our geologists, as Prestwich, who have been strongly inclined to trust in negative evidence. Lyell will very soon publish a little supplement to his Elements & will give an outline of these new facts & many others which he picked up on the continent last autumn.—¹⁰ He visited with Barrande his celebrated region; & will discuss B.’s colonies, which always troubled me as great anomaly.—¹¹

Owen has lately published a new Classification of mammals, taken from structures of Brain;¹² so great an authority ought to be right, but I cannot help always having doubts on a classification founded on one character, however important.— I have had of late a good deal of correspondence with Asa Gray, who has been infinitely kind in giving me valuable information.— I sometimes hope that my Book will be useful as comparing the results which different authors from different data have arrived at; however erroneous my general conclusions may prove.—

Whenever you have time to write, tell me a little what you are about, & believe me, My dear Sir | Your’s very sincerely | Ch. Darwin