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 & w^d allow me to examine them, it w^d be of great service to me.—

Will you please to give my sincere thanks to M^r Alder for the specimens, & for the great trouble he has taken in copying Loven’s paper:⁵ it is a most interesting cirripede, & the type of a new family or order; for it has no relation to Alepas, the animal of which I know well: I must write to Loven;⁶ his description is unfortunately short.— Will you add to your kindness by some time asking M^r Alder to what place the Royal Academy of Sciences, given in the title belongs:⁷ Lady Lyell translates the Title, as “Extract from a Review of the Trans. of the R. Acad. of Sciences. 1^st series 1844., p. 192–4” Secondly will you be so kind as to tell me on what being (for I cannot read word) your specimen of the Ibla is attached.⁸ And Thirdly whether you had any motive for calling your cirripede “Alcippe”, as perhaps I will change my long name of Arthrobalanus for a shorter one.—⁹ Anytime will do for an answer.—

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 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 2^d. 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