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Darwin Correspondence Project

To T. H. Huxley   20 February [1855]1

Down Farnborough Kent

Feb. 20th

My dear Huxley

I send a few specimens of the cementing apparatus of Sessile Cirripedes,2 & shd. be very glad if at some future time you wd have a look at them; merely that I may feel that I have one living witness of this odd structure which I have described.3 I send a single specimen, also, of an ovigerous frænum with its so-called glands;4 as this specimen was in act of moulting it entirely puts out of the question the bodies which you doubt about being foreign organisms.

I saw some time ago that you do not find any anus in the Brachiopod Molluscs;5 I may just mention that this is precisely the case with the Cirripede Alcippe in which rectum & anus are absolutely null.—6

I have this morning just received your Article on Mollusca;7 I am particularly obliged to you for having sent it to me, as I had heard of it & shall be very glad to read it, as indeed everything which you write. But as far as criticism goes, I really do not know enough of the subject to pretend to offer an opinion worth the paper on which it shd be written.

Yours very truly | C. Darwin

This note & specimen &c all goes in a parcel for Dr. Percy.—8

Please look at specimens in following order, with good & varying light & moderately high powers. I shd like to have them back at some future time.— 280. Basal membrane of Coronula; showing cement-glands & ducts simplest structure in any Sessile Cirripede. 219. do of Chelonobia: ducts bifurcating more complicated; cement glands small. 203. do of Elminius: ducts very complicated: main cement trunk tortuous, like a great worm. 285. fragments of basis of Balanus tintinnabulum, after dissolution in acid, showing curious cement glands & bifurcating ducts 179. Piece of ovigerous frænum of Lepas anatiferum, showing glands. N.B. This specimen was in act of moulting, & the old membrane with the old glands & the new membrane with new glands, closely investing the corium, can both be plainly seen. Use 14th. focal distance & good light.—


Dated on the basis of the reference to T. H. Huxley 1855a (see n. 7, below).
See letters to T. H. Huxley, 8 September [1854] and 13 September [1854]. Huxley had examined specimens of cirripedes during his visit to Tenby the previous summer. CD had found the Balaninae, a sub-group of the Balanidae (sessile cirripedes) difficult to dissect, and he had therefore primarily based his views on the Lepadidae (pedunculated cirripedes) (see Living Cirripedia (1854): 134).
See Living Cirripedia (1854), p. 134, where CD described the cementing apparatus in Lepadidae. It was his view that ‘the two cement-glands, with their contents, actually consist of ovarian tubes with their contents … in a modified condition.’
CD described the ovigerous fraena of the Lepadidae and the glandular bodies associated with them in Living Cirripedia (1851): 58–61.
T. H. Huxley 1854b.
T. H. Huxley 1855a. CD’s copy is in the Darwin Pamphlet Collection–CUL.
John Percy, metallurgist, was a colleague of Huxley at the School of Mines.


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.


Sends specimens of sessile cirripedes for corroboration of their cementing apparatus.

Absence of anus in Brachiopoda and Alcippe cirripedes.

Letter details

Letter no.
Charles Robert Darwin
Thomas Henry Huxley
Sent from
Source of text
Imperial College of Science, Technology and Medicine Archives (Huxley 5: 23, 372, 376)
Physical description
4pp, encl Amem 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 1635,” accessed on 1 March 2021,

Also published in The Correspondence of Charles Darwin, vol. 5