To A. A. Gould   20 August [1849]

Dear Sir

I did not receive your very kind note of April 30^th & loan of Cirripedes through M^r Cuming until a fortnight since; for I have been absent from home & all my work interrupted for the last five months. My health became so exceedingly bad, that I could do hardly anything, & I consequently have been to Malvern & tryed the Cold Water Cure under D^r. Gully with great success. I am now at the Cirripedia again, but am allowed to work only two hours a day: I feel truly grateful for your kindness in assisting me: the sessile Cirripedes will come in very useful, when I come to that division,¹ & they shall hereafter be carefully returned to you: I believe I told you that I require to disarticulate a specimen of each species; without this being done it is impossible to describe or recognise the species: I trust you will not object to this; should you do so, there will be time to inform me. The Ibla is a species (not published) which I have named I. Cumingii & was found in numbers by M^r Cuming at the Philippines: I have never seen it from elsewhere, except the specimen from Tavoy sent by you:² it is in some Anatomical respects, perhaps the most interesting cirripede in the world.³

I will send the Scutella to M^r Gray at British Museum, as directed.

I have acted on your kind suggestion & written to M^r Dana

You say “that I have figures & notes of 3 or 4 species of Anatifa which I c^d copy for you if desired”: if you could let me have a specimen of such those figures & notes would be of the greatest service to me, but without you have minutely described the internal surface of the valves, & the Branchiæ of the animal, I find it quite impossible to recognise species of Anatifa. I see in the drawing sent the colours are marked specimens of such w^d be invaluable, for then I sh^d know the colouring.—

I thank you most cordially for your offer of further assistance: from my health & the extreme difficulty of describing the species, I shall certainly be employed a year or two more on the Cirripedia—

Could you tell me in what works M^r Conrad⁴ has described or is likely to have described Cirripedia: in M^r. Cumings collection there as 2 or 3 species (especially a Pollicipes from California) named by him & I am quite at loss to know where to look— Of course I do not intend for one second to hint to you to take the trouble to search for references; but as you have attended so much to shells you may be able to guide me where to search.— I wrote to M^r. Conrad myself on this subject, but either my letter miscarried, or he thought I took too great a liberty in addressing him; anyhow I have had no answer.—

With my sincere thanks | Believe me | Your’s faithfully & respectfully | C. Darwin

If you ever see an Anatifa adherent to a Crab, you may be almost sure it will be new & interesting: there are several species, which I have been compelled to separate under a new generic name:⁵ I am glad to say that I have had to run far more genera together, than to separate & make new ones.—