# To Albany Hancock   [29 or 30 October 1849]

Down Farnborough Kent

My dear Sir

I have to thank you sincerely for many things. Your specimens arrived quite safe: I have as yet taken only a cursory glance at them; for I have an odiously tedious job of compiling long generic descriptions from my specific descriptions. When I have done in a fortnights time, I will enjoy the treat of having a good inspection of Alcippe; I hope by that time your Paper will be out, as it will save me much time in comparing every part with common cirripedia:—indeed I will wait till I can get the number with your Paper:—it is an immense time since I have seen a new form of Cirripedia.1 At same time I will look over my Mollusca & my few notes made at time;2 & if they turn out of slightest interest to you, I shall be heartily pleased by your acceptance of them. I will be careful of the specimens of Alcippe.— Your sketches are very spirited; the cirripede from Australia is the Ibla cuvierana;3 that from Madeira is an unnamed species, which I have unwillingly been compelled to make into a new & insignificant genus; I have called it (supposing name be not used) Machairis celata4 (from being encrusted with bark of the Antipathes): If you have any other cirripedes from foreign localities & wd allow me to examine them, it wd be of great service to me.—

With respect to Lithotrya:10 the shells have relation to diameter of hole, but the shell-parts of full-grown ones, I believe, project beyond their hole; this is hard to know as peduncle shrinks much from drying: holes are bored in all directions: the animal often rises $\frac{1}{4}$ of an inch in its hole from [DIAG WITHIN TEXT] thickness of cup: very young specimens have cups, I believe at earliest period: I cannot describe whole process of fixing in letter, but I must think it quite impossible that any cirripede can sink its basis in any object: I have thought that the larva of Lithotrya instinctively (is this not wonderful) creeps into the crevices of the coral-rocks to that depth, from which it can when nearly full-grown freely reach the surface; in interval I believe it feeds on infusoria in water circulating in the crevices. I once thought that the larva of Arthrobalanus might have bored its hole with its prehensile antennæ, but I cannot now believe this. But there is another view or conjecture, which perhaps is the most probable, viz that the larva (in 2d. stage) boring a minute hole by an acid secreted from same glands, & through same duct & orifices in the prehensile antennæ (alluded to by me in Athenæum) by which afterwards the Cement-stuff is poured out:11 this view would perfectly harmonise with the facts, of which I cannot doubt, namely that the cirripede after metamorphosis can never alter its point of attachment & secondly the apparatus of minute points for enlarging its cavity, in Lithotrya Arthrobalanus & Alcippe, is equally applicable.—

But I shall utterly weary you with this discussion.— Your statements about cavities of Alcippe make me doubt my view of the larva creeping into already existing cavities.—

With my sincerest thanks | Your’s very faithfully | C. Darwin

## Footnotes

See letters to Albany Hancock, [c. 21 September 1849] and 29 September [1849]. CD in fact deferred examining Alcippe until after he had finished with the pedunculated and sessile barnacles. See the correspondence with Hancock early in 1853 (Correspondence vol. 5).
CD refers to his Beagle specimens and the notes he made in his zoological diaries about them during the voyage (DAR 30.1, 30.2; 31.1, 31.2). See letter to Albany Hancock, [26 January – March 1850].
A synonym for Ibla quadrivalvis (Living Cirripedia (1851): 203).
In Living Cirripedia (1851): 133–6, CD named and described it as Oxynaspis celata. CD said he had ‘most unwillingly instituted this genus; but … the one known species could not have been introduced into Lepas or Pæcilasma, without destroying these genera’.
Royal Swedish Academy of Sciences, Stockholm.
The description in Living Cirripedia (1851): 204, reads: ‘New South Wales, attached to a mass of the Galeolaria decumbens, (Mus. Hancock)’. G. decumbens is a polychaete worm.
CD may also have wished to alter the name of Arthrobalanus subsequent to his improved expertise in the comparative anatomy and taxonomy of the barnacles. When he began in 1846 to study this cirripede collected on the Beagle voyage, CD asked Joseph Dalton Hooker to help him name it (see Correspondence vol. 3, letter to J. D. Hooker, [2 October 1846]). The name that was chosen referred to the articulated character of this supposed Balanus. Eventually CD changed the name to Cryptophialus minutus, reflecting the fact that it lived hidden away in a ‘flask-shaped’ carapace, and that it was the smallest known cirripede (Living Cirripedia (1854): 563–6). CD generally noted the derivation of the names he gave to new genera (see Living Cirripedia (1851): 99, 115, and 133). See also letter to J. S. Henslow, 2 July [1848], in which CD asked Henslow to check the correctness of his names.
The Athenæum, no. 1143, 22 September 1849, p. 966, reported CD’s comments on Hancock’s paper at the British Association meeting (see Collected papers 1: 250–1). In Living Cirripedia (1854): 512, CD adopted this chemical means of boring for the genus Verruca but held that Lithotrya, Alcippe, and Cryptophialus formed their respective cavities by mechanical means (ibid., pp. 550, 570).

## Summary

Thanks him for specimens of Alcippe.

Comments on sketches by AH and on cirripede paper by Lovén.

Discusses Lithotrya and its burrowing habits.

## Letter details

Letter no.
DCP-LETT-1262
From
Charles Robert Darwin
To
Albany Hancock
Sent from
Down
Source of text
Maine Historical Society
Physical description
6pp