My dear Huxley

I send a few specimens of the cementing apparatus of Sessile Cirripedes,² & sh^d. be very glad if at some future time you w^d have a look at them; merely that I may feel that I have one living witness of this odd structure which I have described.³ I send a single specimen, also, of an ovigerous frænum with its so-called glands;⁴ as this specimen was in act of moulting it entirely puts out of the question the bodies which you doubt about being foreign organisms.

I saw some time ago that you do not find any anus in the Brachiopod Molluscs;⁵ I may just mention that this is precisely the case with the Cirripede Alcippe in which rectum & anus are absolutely null.—⁶

I have this morning just received your Article on Mollusca;⁷ I am particularly obliged to you for having sent it to me, as I had heard of it & shall be very glad to read it, as indeed everything which you write. But as far as criticism goes, I really do not know enough of the subject to pretend to offer an opinion worth the paper on which it sh^d be written.

Yours very truly | C. Darwin

This note & specimen &c all goes in a parcel for D^r. Percy.—⁸

Please look at specimens in following order, with good & varying light & moderately high powers. I sh^d like to have them back at some future time.— 280. Basal membrane of Coronula; showing cement-glands & ducts simplest structure in any Sessile Cirripede. 219. do of Chelonobia: ducts bifurcating more complicated; cement glands small. 203. do of Elminius: ducts very complicated: main cement trunk tortuous, like a great worm. 285. fragments of basis of Balanus tintinnabulum, after dissolution in acid, showing curious cement glands & bifurcating ducts 179. Piece of ovigerous frænum of Lepas anatiferum, showing glands. N.B. This specimen was in act of moulting, & the old membrane with the old glands & the new membrane with new glands, closely investing the corium, can both be plainly seen. Use $\frac{1}{4}$^th. focal distance & good light.—