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Darwin Correspondence Project

To Albany Hancock   12 May [1850]

Down Farnborough Kent

May 12th

My dear Sir

Owing to a perhaps foolish habit of not reading Periodicals when they come out; I have only just read your very interesting paper on the boring of Mollusca in the Annals;1 & this reminded me that you wished for more information regarding Lithotrya;2 I really do not know what to give. I have 3 specimen of Lithotrya & I enclose one for you. I have picked out one that has lately moulted (this moulting of scales unique in whole order of common Cirripedes.) & therefore has the scales on peduncle,3 with the teeth pretty sharp: the valves of course are not moulted, but the old layers scale or are rubbed off.—

I have not one with the basal calcareous cup; though several have been lent me. I wish you could see the basal cup; I feel sure it wd confirm your opinion that it could not be the borer.—4

I can see no reason yet to alter my opinion, that Lithotrya either crawls into cavity which it enlarges or if not, that the larva has the power of boring a hole, in which it fixes itself & undergoes its metamorphosis.5

I have several foreign species of Clisia6 & I will attend to their to me quite wonderful boring-powers.—7

Yours very sincerely | C. Darwin


A. Hancock 1848, which was published in Annals and Magazine of Natural History. CD’s bound copy of the volume in which this paper appeared is in the Darwin Library–CUL.
Hancock had evidently responded to CD’s letter dated 15 [April 1850], in which CD emphasised the boring capacities of Lithotrya, by asking CD to send specimens.
For CD’s views on the moulting of the scales on the peduncle of Lithotrya, see Living Cirripedia (1851): 336–8.
CD’s final view was the first alternative: that the peduncle of Lithotrya was the wearing agent (Living Cirripedia (1851): 345–8).
CD gave priority to Verruca as the name of this genus.
CD concluded that, unlike the pedunculated genus Lithotrya, Verruca did not burrow mechanically but by means of a solvent excreted by the cement ducts (Living Cirripedia (1854): 512–18).


Hancock, Albany. 1848. On the boring of the Mollusca into rocks, &c.; and on the removal of portions of their shells. Annals and Magazine of Natural History 2d ser. 2: 225– 48.

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.


Mentions AH’s ["On the boring of the Mollusca into rocks", Ann. & Mag. Nat. Hist. 2d ser. 2 (1848): 225–48]. Discusses anatomy and habits of Lithotrya.

Letter details

Letter no.
Charles Robert Darwin
Albany Hancock
Sent from
Source of text
American Philosophical Society (Mss.B.D25.93)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 1327,” accessed on 4 June 2023,

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