My dear Sir

I am much obliged for your note received this morning, with as full answers as you could send to my queries, & for a former note received some time since with excellent remarks on the classification of Alcippe.¹ I have been very troublesome, but shall cause no more; & am truly obliged for all you have for me. If in your power, I am sure you will kindly in course of summer get me a few specimens for the British Museum & for distribution.—

I yet have a few specimens of other cirripedes of yours, in my possession.—

I have now finally finished with my S. American boring cirripede; & this has utterly confounded my previous confusion how to rank Alcippe & it; for they present some most remarkable similarity, for instance they are both bisexual, with the males remarkably alike.—& yet in what I must consider their fundamental organisation, & in their metamorphosis, they are so totally unlike that I cannot place them in the same order!²

My classification does not satisfy myself, nor, I fear, you if you ever look to my volume on this point.

Pray believe me | My dear Sir | Yours truly obliged | Ch. Darwin

The bosses on the cirri of Alcippe are hardish or crustaceous, they are all four opposed to each other & the little ridges on them are crenated; these facts made me suspect that their use was not for simple prehension, but for triturating the food;³ & now I find in my analogous S. American burrower, & in no other cirripede that the œsophagus is provided with the most beautiful discs set with teeth, & brushes of hairs, worked by muscles, certainly for triturating food; which strengthens my notion.—⁴