My dear Hooker

Your drawing is quite beautiful;² I cannot thank you enough, & I feel, as I before said guilty—your goodnature is as wonderful as mesmerism.— I have been reading heaps of papers on Cirripedia, & your drawing is clearer than almost any of them. The more I read, the more singular does our little fellow appear,³ & as you say, looking at its natural size, a microscope is a most wonderful instrument. How different would the drawing have been, if I had employed an artist! not to mention the invaluable assistance of having my loose observations confirmed, & the several points observed only by you.— I shall of course state this in the beginning of my paper,⁴ & when I have not seen the thing, give it on your authority.

I have a few questions to ask & I sh^d. be much obliged for an answer before very long.—

(1) Is the fold at the posterior & lower end of stony, dentated valve, fimbriated & of the same texture, as the two inner fleshy & fimbriated valves? it is shaded in the same manner.—

(2) Regarding fig. 13 & 14, you speak as if you thought the kind of bars at the base of the two jaws were muscles; do you feel sure of this, for on the voyage & since they felt decidedly hard & shelly, & Burmeister has described similar hard supports to the jaws in Lepas.⁵

(3) Did you happen to notice, whether the cherotherium footsteps pointed upwards or to the base of animal? I can look, if you do not remember.—⁶

(4) I see you have not put in, any trace of the oblique articulation between the head & sternum; do you deliberately give it up? I certainly thought that there was one.—

(5) The head in fig. 10 seems to me hardly distinct enough dorsally from body; whereas in fig 11. it appears to me, just as I saw it; I can get artist to vary the line a trifle.

(6) Would you please return my own wretched drawing; & I sh^d be very much obliged for a copy, in same style as your others, of my fig. with legs retracted; the merest outline would do; I want it because the appearance of these larvæ are now so utterly different from what they were when alive & it shows position of legs when fully retracted.— I describe it, as pointed coffin-shaped, & twice as long as the egg in the last previous state, (your fig. 21) that is not including the two projections: I send a tracing of your two figures, for the scale sake: I see I state that the two anterior club-shaped organs in state on fig 21. are very much longer than in fig 20.

I have not knowledge enough to discuss the nature of the limbs in this larva; & indeed I doubt whether any one has, for its relations are to various very distinct families.

I return the lens, with very many thanks, & with ditto for having written to Adie—⁷ My lens have been altered (for 3^s. 6^d. only!) & a great comfort it is. You really are the most goodnatured man I ever knew,—too goodnatured for so true a zealot to your own science,—and I thank you cordially—

Ever yours | My dear Hooker, C. Darwin

P.S. | I find that I have one other query.— In fig. 5. the inner & third tunic, is not represented as enveloping whole animal & ovisac, but folding in & terminating at the posterior & lower edge of ovisac; hence the ovisac appears like a reduplication of this 3^d & inner membrane. My impression is different, viz that this 3^d inner tunic is continuous with muscular tunic.— Pray mind, I beg you not for this or any other query, to dissect any more, indeed I doubt whether you have the specimens; for I will look to this point, only I have so very much more confidence in your observations than in mine own, that I am glad to know your impression.— I am drawing up my description, which runs out much longer than I expected or like.—