My dear Sir

I have delayed thus long to thank you for your letter of the 29^th of July, in order to be able to tell you of the safe arrival of the specimens;¹ they came to me this morning perfectly safe; I may, however, remark that on two of the cards there was a place as if a single shell had been attached, but now missing.— I am astonished at the richness of the collection, & am most truly grateful to you for sending it to me, & for all the trouble which you have so generously taken in the midst of your own far more labours. Indeed I fear that my monograph will greatly disappoint you, though I have taken all the pains I could over it.— You must be impatient, (as well as my very kind friend Prof. Forchhammer) to receive back your collections they shall be sent as soon as the Plates are engraved by M^r Sowerby, & I know that considerable progress has been made.—

I will assuredly attend to your suggestions about M. Augelin.—²

You ask me whether I am now at work on the Pedunculated or Sessile cirripedes; I have finished in M.S. the former & have just described my 41^th species of the genus Balanus: the sessile cirripedes will take me at least six months more. I am therefore quite ready for both pedunculated & sessile, if you can find time to send me any specimens; I especially value those with known habitats. I assure you the cirripedia are very troublesome from their great variation; shape, state of surface, size, & often colour go for nothing.—

I sh^d be very grateful for the Paper which you kindly offered to send me on the Lithotrya from the Nicobar islands; of which the Plate interested me much.—³

As you have attended to the northern Cirripedes can you tell me, wherein I shall find a description of Balanus or Lepas Uddevallensis of Linnæus; I have seen two species thus named from beds of Uddevalla; viz B. tulipa alba of Chemnitz & B. sulcatus of Brugiere (=Lepas balanus of Linn.).—⁴

Believe me I feel truly grateful for all your great kindness, & | I remain, yours very faithfully | C. Darwin

I think the following direction is safer, for a parcel, C. Darwin Es^q 7. Park St^t. Grosvenor Square London it is my Brothers House; & he will communicate to me