To J. D. Dana 29 December 
Down Farnborough Kent
Decr 29th —
My dear Sir
I thank you very sincerely for your very kind remembrance of me & my cirripedial pursuits; I have no doubt in due time I shall receive the curious unattached cirripede from off Borneo.—1
With respect to Bell,2 allow me to assure you that when I asked him for pamphlet for you, he expressed the most lively pleasure in being able to send to you, anything you required. On the other hand, he is overwhelmed with professional work & with his Secretaryship of the Royal Soc: moreover he is apt to be a dilatory correspondent, as I have found him on several occasion, but at the same time, I really believe a more goodnatured, kind-hearted man does not exist.— Upon the whole I doubt whether he could enter into a long correspondence with any person, but I feel pretty sure he would be more interesting in writing to you than to almost any other Naturalist in the world.— I have given my opinion with the utmost frankness as far as my judgment goes.—
I thank you particularly for calling my attention to the union of the prehensile antennæ of the larvæ of Cirripedes, in relation to a similar structure in other Crustacea.3 I have attended particularly to this attachment of the antennæ, but I can consider it only as it were an accident due to the attachment of both antennæ & the immediately surrounding parts, to the supporting surface.— I doubt how far this attachment can be called organic (though I have put by specimens in order to examine further into this point); the cementing stuff generally presents no trace of structure, though sometimes in its early stages it consists of a mass of cells. Would it be asking too great a favour to beg you to send me one or more specimens (if not very rare) of any crustacea thus attached & still adherent to a fish, or other body?4 How is the exuviation managed in the Lernææ with the united prehensile legs? I feel the greatest interest on this point; for I have found such wonderfully diverse forms in the class Cirripedia, that I have been driven to one character, namely their means of attachment, by a cement ([reverse question mark].tissue?) which first comes out of the prehensile antennæ of the larvæ, & subsequently through special apertures, (varying remarkably in the different families, & even genera) formed usually at each fresh exuviation. But the strangest point is that this cement is conveyed by a duct leading from a gland, which is nothing but a modified part or continuation of one of the ovarian branches.—5 I do not expect you to believe me, though I feel pretty sure of my accuracy; perhaps you will be so kind as not to mention this fact as I shd. like to publish myself this one little point. Hence it is that I am anxious to know how any parasitic crustacea are attached, or how the limbs are attached to each other; from what I had read, I had thought it was exclusively effected by claws to the fish.—
Pray forgive the length of this letter, & accept my sincere thanks for all your kindness | Believe me | Your’s very sincerely | C. Darwin
Discusses attachment of antennae in larvae of cirripedes.
Asks for information about how parasitic cirripedes are attached to host.
Please cite as
Darwin Correspondence Project, “Letter no. 1381,” accessed on 28 September 2016, http://www.darwinproject.ac.uk/DCP-LETT-1381