My dear Sir

I have not for some years been so much pleased, as I have just been by reading your most able discussion on coral-reefs.— I thank you most sincerely for the very honourable mention you make of me.— This day I heard that the Atlas¹ has arrived & this completes your munificent present to me.— I have not yet come to the chapter on subsidence, & in that I fancy we shall disagree, but in the descriptive part, our agreement has been eminently satisfactory to me, & far more than I ever ventured to anticipate.— I consider that now the subsidence theory is established.—

I have read about half through the descriptive part of the volcanic Geology (last night I ascended the peaks of Tahiti with you, & what I saw in my short excursion was most vividly brought before me by your descriptions) & have been most deeply interested by it: your observations on the Sandwich craters strike me as the most important & original of any that I have read for a long time. Now that I have read you, I believe I saw at the Galapagos, at a distance, instances of those most curious fissures of eruption. There are many points of resemblance between the Galapagos & Sandwich is^ds (even to the shape of the mound-like hills) viz in the liquidity of the lavas, absence of scoriæ & tuff-craters.—² Many of your scattered remarks on denudation have particularly interested me; but I see that you attribute less to sea & more to running water than I have been accustomed to do.— After your remarks in your last very kind letter, I could not help skipping on to the Australian valleys, on which your remarks strike me as exceedingly ingenious & novel, but they have not converted me: I cannot conceive how the great lateral bays could have been scooped out, & their sides rendered precipitous by running water.³ I shall go on & read every word of your excellent volume.—

I have been endeavouring to get the papers &c, which you want. I have procured the 4 first Parts of Thompson Researches;⁴ the 5^th part has been lost, & even the Publisher knows not how;—this I hope you will allow me to give you.— Professor Bell has sent me for you copies of all his Papers;⁵ I have applied elsewhere, but whether I shall succeed I know not. In the course of two or three weeks I will send all off to you through Delf—⁶ I will gratify myself by including copies of several Geolog. papers of my own.

If you look over my Geolog. Instructions,⁷ you will be amused to see that I urge attention to several points, which you have elaborately discussed. I lately read a paper of your’s on Chambers’ book⁸ & was interested by it— I really believe that facts of the order described by Chambers, occur in S. America, which I have described in my Geolog. Volume. This leads me to ask you, (as I cannot doubt that you will have much Geolog. weight in N. America) to look to a discussion at p. 135 in that volume, on the importance of subsidence to the formation of deposits, which are to last to a distant age.⁹ This view strikes me as of some importance.

When I meet a very goodnatured man, I have that degree of badness of disposition in me, that I always endeavour to take advantage of him: therefore I am going to mention some desiderata, which if you can supply I shall be very grateful, but if not no answer will be required. I want much a specimen of Coronula denticulata of Say on the Kings Crab of U. States.—¹⁰ I especially want any species of the genus Scalpellum¹¹ (of course I w^d. return any specimens only lent me, only I require to open one specimen of each kind). How far south in Antarctic sea did you meet any Anatifas; I have Sir J. Ross’ collection¹² but there are no precise localities: the common Antartic Anatifa I have called australis; it differs from all northern forms.—

Do you know any Crustacean which bores in calcareous rocks or shells?¹³ Do you know any crust, whose oviducts open at or near the antennæ? Did you discover where the ovaria are situated in Phyllosoma?¹⁴ Lastly can you tell me whether any list has been published of the plants found on Elevated coral islands; or could you procure me such a list.— Now can you forgive me asking you all these questions; please observe, that I beg you not to answer, without you can inform me on these points (which I well know is not likely) or help me with respect to above specimens.—

I do not know whether Sir C. Lyell has as yet seen your Report, but I wrote to him yesterday & told him how much many parts of your volume would interest him. What an unfortunately short time you were permitted to stay at many of the places, yet how much you managed to see!

With my most sincere thanks for the honour you have done me & the gratification you have afforded me | Pray believe me | Yours very sincerely | C. Darwin

Thank you for your Conspectus Crust,¹⁵ but I am sorry to say I am not worthy of it; though I have always thought the Crustacea a beautiful subject.