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Darwin Correspondence Project

To Henri Milne-Edwards   18 November [1847]

Down Farnborough Kent

Nov. 18th.

My dear Sir

I take the liberty of writing to you,1 for the chance of some specimens which I possess, interesting you. Mr Goodsir2 has figured in Eding. New Phil. Journal, July 1843, (Vol. 35, p. 88) what he considers,, certainly quite erroneously, the male of the Balanus:3 I have found 5 individuals of this Lernæa like strange creature within the sack, (or so called mantle) of the Balanus elongatus of the British seas.—4 Mr Goodsir, also, figures, what he considers a new genus of isopodous Crust, as parasitic on his male Balanus. I have found the same, but I believe it is the larva-form of the Lernæa: I have this imagined larva in every stage of development & well preserved & thousands of individuals of them. In fact the Lernæa is a great sack full of these little crustaceans larvæ, which in their early state exist as curious kidney-shaped, papillose bodies. Lastly within the same Balanus, in which 3 of the Lernæa were included, I found a little perfect or mature crustacean animal, something like the larvæ, this I suspect may be the male of the Lernæa. If, then, my conjectures are correct (& I beg to observe that I have only cursorily looked at these specimens) I have the male, female & the larvæ in different states, of this singular Lernæa like animal, which is parasitic on Balanus.—5

I do not know whether you are now attending to Crustacea or would think these specimens worth your acceptance.6 If you will look at Mr Goodsirs drawings you will be able to judge: they seem to me very curious.— Should you like these specimens, I could send them through M. Bailliere, the Bookseller.—7 Should you think them worth having, it would give me great pleasure to send them to you, to whose publications, I have long owed much pleasure & instruction.—8

I trust anyhow that you will excuse my having troubled you with this letter & I beg to remain with much respect & admiration | Yours faithfully | C. Darwin

Not knowing your address I have directed this to the Academy of Sciences9


CD had met Milne-Edwards at the British Association meeting in Oxford in June 1847 (see letter to Henri Milne-Edwards, 1 September [1848]) and both Charles Lyell and Richard Owen described events at which he was present (see K. M. Lyell ed. 1881, 2: 130 and R. S. Owen 1894, 1: 299).
Henry D. S. (Harry) Goodsir, conservator of the Museum of the Royal College of Surgeons, Edinburgh.
Goodsir 1843, in which Goodsir described what he believed to be the male of a Balanus. Although cirripedes were generally thought to be hermaphrodites, Goodsir believed that if they were crustaceans, as John Vaughan Thompson’s work indicated (Thompson 1830), they should, like the Crustacea, have separate sexes. Furthermore, he reasoned that the males would resemble the small, larva-like male of the Lernaea (see n. 4, below), to which group he believed the Cirripedia were most closely allied. Accordingly, when he discovered a small Lernaea-like organism parasitic within the sack of sessile cirripedes, he believed he had discovered the male of the species. In addition, Goodsir described what he took to be an isopod crustacean parasitic on the ‘male’ Balanus.
Lernaea, like the Cirripedia, was a much discussed group at this time. In his series ‘Illustrations in British Zoology’ published in Magazine of Natural History 8 (1835): 565, George Johnston wrote of this family: Of all the curious creatures which the naturalist meets with in his researches, there are none more paradoxical than the Lernææ; none which are more at variance with our notions of animal conformation, and which exhibit less of that decent proportion between a body and its members which constitutes what we choose to call symmetry or beauty. The identification of their larvae in the 1820s showed them to be Crustacea, but their place within the class remained for many years a point of debate. The male Lernaea was first described in the 1830s, presenting a stark contrast to other members of the Crustacea by being much smaller in size than the female, larva-like in appearance, and semi-permanently attached to the female. CD’s parasite was not actually Lernaea, a parasitic copepod, but an isopod now classified as Hemioniscus balani.
From his own observations of these organisms, CD believed that Goodsir’s ‘male’ was, in fact, a crustacean related to Lernaea and that the parasites he found on it were actually the larval stage of this crustacean. If his specimens indeed included males of this species, they would be of great interest to naturalists studying Crustacea, who frequently found it difficult to locate all these forms together.
Milne-Edwards apparently was not interested in these specimens (see letter to Henri Milne-Edwards, 1 September [1848]). CD later offered them to James Dwight Dana, who was at work on a monograph of the Crustacea collected by the United States Exploring Expedition (Dana 1852–3) (see letter to J. D. Dana, 24 February [1850]).
Jean Baptiste Baillière et ses fils, booksellers, had offices in both London and Paris.
Milne-Edwards was also the author of an important essay on classification (Milne-Edwards 1844) and other works published in the Annales des Sciences Naturelles, which CD read in December 1846 (DAR 119; Correspondence vol. 4, Appendix IV).
Milne-Edwards had been elected to the zoology section of the Académie des Sciences in 1838.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Goodsir, Henry D. S. 1843. On the sexes, organs of reproduction, and mode of development, of the cirripeds. Account of the Maidre of the fishermen, and descriptions of some new species of crustaceans. Edinburgh New Philosophical Journal 35: 88–104.

Milne-Edwards, Henri. 1844. Considérations sur quelques principes relatifs à la classification naturelle des animaux, et plus particulièrement sur la distribution méthodique des mammifères. Annales des Sciences Naturelles (Zoologie) 3d ser. 1: 65–99. [Vols. 4,6,8]

Owen, Richard Startin. 1894. The life of Richard Owen … With the scientific portions revised by C. Davies Sherborn; also an essay on Owen’s position in anatomical science by the Right Hon. T. H. Huxley, F.R.S. 2 vols. London: John Murray.

Thompson, John Vaughan. 1830. Memoir IV. On the cirripedes or barnacles; demonstrating their deceptive character; the extraordinary metamorphosis they undergo, and the class of animals to which they indisputably belong. In Zoological researches, and illustrations; or, natural history of nondescript or imperfectly known animals. 6 vols. Cork. 1828-34. Facsimile reprint. London:


Offers HM-E some specimens of Lernaea, a crustacean parasite on Balanus elongatus.

Mentions opinion of Harry Goodsir about a form CD believes to be the larva of Lernaea.

Letter details

Letter no.
Charles Robert Darwin
Henri Milne-Edwards
Sent from
Source of text
American Philosophical Society (Mss.B.D25.66)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 1136,” accessed on 25 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 4