To J. D. Hooker   [19 May 1846]¹

My dear Hooker

It has just flashed across me suddenly, that I brought home a very few plants in Spirits of Wine (with the colours noted) namely some sea-weeds, & 2 Orchideous plants from shady parts of Forests of T. del Fuego—a Calceolaria from Elizabeth Is^d. St of Magellan (which at the time I thought a wonderful production of nature!) & a salt-plant from near a Salina at Port St Julians in same jar with Opuntia Darwinii from do.— Has Henslow ever given you these? He is now in Cambridge & c^d probably find them (if you have not seen them & would like them) & this is the reason I write today, though not well— I go to London for a few days tomorrow.

I received the other day another number of your Antarctic Work, & I have now 4 or 5 to read: Hopkirk did not come: I mention this not at all as wanting immediately but in case of any accident. Have you seen Bunbury’s Paper in Last number of Geolog. Journal on American Coal-plants: your observations on uniformity of Floras on W. coast of S. America under equable climate bears on his remarks,² & I will point them out to him; that is, if I am not confounding one of your letters, so valuable to me, with your published remarks.—

Many thanks for your most critical & scientific, & I don’t doubt true specific character of Dieffenbach; but I am sorry you took so much trouble about it: I asked chiefly out of simple curiosity, & partly from having been urged to recommend him as Naturalist on any occasion which might turn up, & I was quite unable to make up my mind about him.— There has always struck me as a want of originality in him.—

I am delighted that you are in the Field, geologising or palæontologising:³ I beg you to read the two Rogers’ account of the Coal-fields of N. America; in my opinion they are eminently instructive & suggestive: I can lend you their resumé of their own labours & indeed I do not know that their work is yet published in full.⁴ L. Horner gives a capital balance of difficulties on the Coal-Theory in his last Anniversary Address, which, if you have not read, will, I think interestyou.—⁵ In a paper just read an Author throws out the idea that the Sigillaria was an aquatic plant, I suppose a Cycad-Conifer with the habits of the Mangrove.—⁶ From simple Geological reasoning, I have for some time been led to suspect, that the great (& great & difficult it is) problem of the Coal would be solved on the theory of the upright plants having been aquatic— But even on such, I presume improbable notion, there are, as it strikes me, immense difficulties; & none greater than the width of the coal-fields. On what kind of coast or land could the plants have lived? It is a grand problem, & I trust you will grapple with it: I shall like much to have some discussion with you. When will you come here again?

I am very sorry to infer from your letter that your Sister⁷ has been ill.

Ever yours | My dear Hooker | C. Darwin

I have heard today that Lyell has found Cheirotherium footsteps in true coal-measures Palæozoic rocks of America!!! Hurrah!⁸