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Darwin Correspondence Project

To Albany Hancock   25 December [1849]

Down Farnborough Kent

Dec. 25th.

My dear Sir

I am very much obliged for your last very interesting letter, with your answers to all my queries, & the copy of your Paper, which I am very glad of, though I take in the Annals.—1

I have not yet looked at Alcippe for I have found my writing work run out, & I have lately received several new pedunculate species to describe.— I have had such a misfortune in the loss of a parcel of cirripedes from Copenhagen, amongst which was the curious Alepas squalicola! the knowledge of which I owe to Mr Alder’s kindness.— I have of course read your description of Alcippe, & it is most clear & definite: I hope to put Arthrobalanus in same order with it,2 but it will be stretching a point to do so, & they must form distinct families, more distinct than any Pedunculate & any Sessile cirripede are from each other.— I hope before long to indulge in a look at Alcippe.

I have had occasion to re-look over many specimens of Lithotrya,3 & am as fully convinced as ever that the basal cup is fixed at very early period, & is never moved.— In one specimen several specimens were embedded in rock parallel but in reversed positions (& others at right angles) & of the parallel ones the greater number had their capitulums (ie shell & or valves) directed from the exterior surface of the rock inwards, so that they cd never reach the surface, & must have lived in subterranean cavity: I am as much as ever in dark, whether the larva creeps in, or bores in.—

I had intended, but forgot, to ask you about the Clitia,; all which I have seen (except some rare foreign species which I have not yet touched) were fixed on fuci & stones; &, if it be not asking too great a favour, I shd be very much obliged, if you would permit me to look at any fixed on shell. Several months ago I had one rather careful inspection of the basal membrane & was much surprised not to be able to see the prehensile antennæ of the pupa, or any orifices for the cement-stuff; yet from analogy I can hardly doubt that Clitia fixes itself like all other Cirripedes, in the manner briefly explained by me to Brit. Assoc.—4

In case of Coronula, Tubicinella & Chelonobia I have fancied, that the sinking was entirely or chiefly owing to growth of surrounding parts of the animal to which the cirripedes were attached. I am much surprised about Clitia, it shows me that there is even in common cirripedes something about their attachment which I do not understand at all.— I have seen, as I believe, that the cement could corrode through membrane of its own peduncle but not act on the calcareous scales supported by this membrane; so that your fact of the Modiola is still odder, & I hope that you will allow me to quote it from you.—5

I have seen the larvæ of most of the species of Anatifa, & I think of A. vitrea,6 but I have had either to dissect them out of egg & just after their escape, & never as yet when naturally sent forth from parent. In the state, in which I have seen them, they certainly had not any “process or pedicel”; but exactly at the spot figured by you, lies their mouth, which is very slightly prominent, without any trophi, & leading into an œsophagus running anteriorly & lost in cellular matter.7

If you cd let me have a few of these specimens I shd be very much obliged; & especially if you wd give me any precise observations of your own on this “pedicel”, for I do not in the least doubt that, with all your experience in dissecting, your observations wd be more trustworthy than my own.— Goodsir figures something like a masticating organ attached to base of legs of larvæ,8 which I cd never see, & which if such exist, wd be a strange coincidence with Limulus.— No doubt you are aware that in all Cirripedes the larva from the stage which you have figured, becomes (so called) bivalve, hexapod, with prehensile antennæ binocular &c.; & when it attaches itself it is in fact a natatory pupa for it has no mouth only a rudimentary shrivelled œsophagus, surrounded by the forming trophi of the young cirripede.— Arthrobalanus alone passes the 1st larva stage in egg, & appears when first born with prehensile antennae & two eyes. &c.—

But perhaps I weary you with these details; one forgets that others do not care so much for a subject, as he who is at work on it.—

I have not yet gone through my bottles for Mollusca, but will you be so good as to send me one line, to say whether you care for any naked terrestrial (as Vaginulus, Parmacella) or aquatic naked mollusca, or for any of Cuvier’s “Tectibranches” as Aplysia &c.—or whether exclusively for the Nudibranch.; I believe I have a few of each order.—

I fear you will think that I have written to you at unreasonable length.— Pray believe me, | My dear Sir | Your’s very sincerely | C. Darwin

I begin to think I shall spend my whole life on Cirripedia, so slow is my progress working only 2 to 3 hours daily.—


A. Hancock 1849b.
See letter to Albany Hancock, [c. 21 September 1849], n. 4.
CD refers to his comments on Hancock’s paper, published in the Athenæum (Collected papers 1: 250–1).
The excavating apparatus of Clitia (Verruca strömia) is discussed in Living Cirripedia (1854): 512–18. CD concluded that, unlike other cirripedes which excavate by mechanical means, Verruca does so by secretion through the cement ducts of a material that acts on the shell to which it is attached, provided the shell is not protected by an epidermis. Hancock’s description of excavation in Clitia is cited, but no reference is made to the mussel genus Modiolus, to which, among others, Verruca attaches itself.
Described as Lepas fascicularis (Living Cirripedia (1851): 92–9).
Hancock’s observation is cited in Living Cirripedia (1851): 11 in CD’s discussion of the mouth in the larval stages.
Goodsir 1843. CD discussed this point without mentioning Harry Goodsir in Living Cirripedia (1851): 12, but he did refer to the anomalous structure of the mouth in Limulus, ‘that most ancient of crustaceans, and therefore one likely to exhibit a structure now embryonic in other orders.’


Athenæum. 1844. A few words by way of comment on Miss Martineau’s statement. No. 896 (28 December): 1198–9.

Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.

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.

Living Cirripedia (1851): A monograph of the sub-class Cirripedia, with figures of all the species. The Lepadidæ; or, pedunculated cirripedes. By Charles Darwin. London: Ray Society. 1851.

Living Cirripedia (1854): A monograph of the sub-class Cirripedia, with figures of all the species. The Balanidæ (or sessile cirripedes); the Verrucidæ, etc. By Charles Darwin. London: Ray Society. 1854.


Discusses the new genus, Alcippe, described by AH ["Notice of the occurrence on the British coast of a burrowing barnacle", Ann. & Mag. Nat. Hist. 2d ser. 4 (1849): 305–14]. Comments on Lithotrya, Clitia, and Anatifa. Discusses cirripede larvae. Asks which Mollusca specimens AH wishes to borrow.

Letter details

Letter no.
Charles Robert Darwin
Albany Hancock
Sent from
Source of text
American Philosophical Society (Mss.B.D25.87)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 1280,” accessed on 16 June 2021,

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