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Darwin Correspondence Project

To J. D. Dana   15 February [1852]

Down, Farnborough | Kent

Feby. 15th

My dear Sir

In a weeks time I hope to send to you two volumes on the Fossil & Recent Lepadidæ.1 If you have time & inclination, I shall be delighted if you will look at the latter, more especially at the sexual relations of Ibla & Scalpellum. I hardly expect to be believed on this latter head, though I am well convinced of the truth of my statements, for I honestly & carefully & repeatedly went & rewent over my dissections.—2

With the two vols. I send a Crustacean, taken by Capt. Sulivan3 R.N. out of a Dolphin’s stomach amongst the Gulf Weed:4 I have almost forgotten the very little I ever knew about the Crustacea; but this seems to me a very curious form, & therefore I shall be much pleased if it turns out worthy of your acceptance & description. When I first saw it much shrunk, I actually thought it was the larva of some Homopterous insect!! I call your attention to some fragments, (as I suspect), adhering to the legs, of the curled horns on the carapace; this, however, may be a mistake, as I did not choose to disturb them.

I have examined the Sporillus, which you so very kindly sent me:5 it is a very curious species of Acasta, & cannot be separated from that genus: I have from Sumatra a distantly allied form embedded in the bark of an Isis:6 I have no doubt your specimens had been originally imbedded in some analogous production;7 for they had long lain dead, & carbonate of lime had been deposited on their insides. Do you remember did you dredge up at same time any such corticiferous coral. &c.?— Have you published any name: in my M.S. I have called it, Acasta sporillus: do you object to this, supposing no name yet published? I presume I may state that I owe the specimens to you.?8

And now I am going to beg you to do me a great favour, namely, as far as you can, to give me the names & geographical distribution, of three or four sma〈ll〉 pieces of coral (not to be returne〈d)〉 in which cirripedes were imbedded. I can only spare small fragments, but I have taken care that they resemble the whole pieces in my possession. I have no habitats for the cirripedes in question, & thus hope for the chance (& I know it is a chance) of asertaining their habitats with more or less certainty by that of the corals.9 I am very anxious on this head.— I trust that you will forgive this trouble.

Pray believe me, with my best hopes that you are well & prosperous, Yours with much respect, very sincerely | C. Darwin

The corals shall be numbered & so you can easily refer to them in your answer.—


See letter to J. D. Dana, 9 September [1851].
CD refers to his discovery of deviations from the normal hermaphroditism of cirripedes: separate sexes and also males complemental to hermaphrodites. See Living Cirripedia (1851): 281–93 for a ‘Summary on the nature and relations of the males and complemental males, in Ibla and Scalpellum’.
Bartholomew James Sulivan, a shipmate on the Beagle voyage, had recently returned from the Falkland Islands, where he had been cattle-farming while on leave from the Navy.
Dana was currently at work on a monograph of Crustacea collected by the United States Exploring Expedition, 1838–42 (Dana 1852–3). CD had earlier sent Dana specimens of a Lernaea-like crustacean he had found adhering to a Balanus (Correspondence vol. 4, letter to J. D. Dana, 24 February [1850]). Unfortunately, the specimen referred to in this letter was lost in the mail (see letter to J. D. Dana, 8 May [1852]).
Dana had sent CD two specimens dredged up from the Sooloo Sea in the East Indian Archipelago (see Correspondence vol. 4, letter to J. D. Dana, 8 October 1849). These were described in Living Cirripedia (1854): 319–21.
Acasta purpurata, found embedded in a species of horny coral. CD examined a specimen from Hugh Cuming’s collection (Living Cirripedia (1854): 318–19).
CD repeated this view in Living Cirripedia (1854): 319–20, although Dana assured him that he had dredged up unattached living specimens (see letter to J. D. Dana, 25 November [1852]). A major character of the genus was that it was found embedded in sponges or sponge-like substances.
CD retained the name Acasta sporillus.
Dana, who had previously published a monograph on the coral collected during the United States Exploring Expedition (Dana 1848), identified three of the species of coral, enabling CD to give the habitats for several members of the genus Pyrgoma. See Living Cirripedia (1854): 361 n., 363 n., and 369 n., where CD thanked Dana for his assistance.


Sending first volumes on Living and Fossil Cirripedia. Solicits JDD’s opinion, especially on sexual relations of Scalpellum and Ibla, on which he "hardly expect[s] to be believed".

Sends unusual crustacean specimen collected by B. J. Sulivan.

The Sporillus sent by JDD is a very curious species of Acasta [see Living Cirripedia 2: 319].

Asks JDD to identify and give geographical distribution of pieces of coral in which some cirripedes are imbedded.

Please cite as

Darwin Correspondence Project, “Letter no. 1473,” accessed on 30 April 2017,

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