To Japetus Steenstrup   20 May [1850]

Down Farnborough Kent

May 20th

My dear Sir

I thank you very sincerely for your last letter which answered all my long list of questions quite fully & satisfactorily.1 Mr. J. Sowerby (the author of Min: Conch:)2 is now drawing your specimens; but from having his hands very full of work he is, I am sorry to say, much delayed: for my own sake I do all I can to urge on his progress. I wait with eargerness to receive your northern Cirripedes & remarks: I am now at work on the Genus Balanus & very difficult I find it, as many species are quite undistinguishable by any one external character. I thank you much for the drawing of Lithotrya: I think I may have the same species from Timor: but the manner of boring here indicated is quite new to me.3

I have heard of your work on Hermaphroditism,4 but have not seen it, though I have long wished to do so; for on merely hypothetical grounds I have always thought Hermaphroditism improbable.5 Alas I cannot read Danish at all, & German with extreme difficulty. How much shame does your perfect English cause me!— You will perhaps be interested by hearing that I once found a Balanus which had had its probosciform organ cut off & healed absolutely imperforate, & yet the ova had been impregnated & contained larvæ; some of the neighbouring individuals in the cluster having certainly impregnated these ova.6 I have two cases of bisexual cirripedes, the male differing considerably from the female & being parasitic within the sack of the female.7

Pray believe me With feelings of much respect & gratitude, | Your’s sincerely | C. Darwin

3
Lithotrya nicobarica. For its manner of boring, see Living Cirripedia (1851): 336–47.
4
Steenstrup 1845a. In Living Cirripedia (1851): 55 n., CD referred to Steenstrup 1846 and thanked George Busk for providing him with an English translation from the German. He recorded having read this work on 28 November 1850 (DAR 119; Correspondence vol. 4, Appendix IV).
5
Living Cirripedia (1854): 271. CD doubted that animal hermaphrodites fertilised themselves; he believed cross-fertilisation was necessary between two such organisms (see Natural selection, pp. 42–6). His work on the sexual relationships of cirripedes was critical in establishing this belief (ibid., pp. 44–5).
6
See the description of specimens of Balanus balanoides from Tenby, South Wales (Living Cirripedia (1854): 101–2).
7
Ibla cumingii and Scalpellum ornatum (Living Cirripedia (1851): 189–203, 248–53).

Manuscript Alterations and Comments

1.5 & remarks:] interl

Please cite as “DCP-LETT-1330,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-1330