My dear Sir

I am ashamed at myself to think how long I have taken to send you my Mollusca:² I have now got them in a Bottle, & will send with them a catalogue of localities; there about 60 packets, though some are duplicates— I send with them the rudest notes of colour & size made at time.³ The colours are given by comparison with Pat. Symes’ nomenclature.⁴ The notes are those of an ignorant schoolboy as I was almost then, & shamefully written; I w^d have copied them out, if they had had any value.— Will you nevertheless please preserve these notes, for as one sometimes likes to see an old book, so I like to keep my wretched zoological notes.— I fear my specimens can be of hardly any interest to you; they must be so shrunk from the Spirits— I think there are one or two new genera— I will despatch the Box with large bottle on next Wednesday,—the first day our Carrier goes.— You will understand I do not want specimens ever returned.— If there sh^d be any part of M.S. which you by chance sh^d wish to read, I will with pleasure copy it.—

Very many thanks for the Clitia:⁵ it has astonished me & convinced me of my ignorance.— I entirely give up the burrowing of your Alcippe & my Arthrobalanus, I only do not give up Lithotrya⁶ from its large mishapen cup being so ill-formed for burrowing & from its having a beautiful rasping apparatus. How difficult it is to discuss any point by letter; I now see that I omitted to mention to you, that all round the base (& therefore widest part) of the head or shell on the top of the peduncle, there is a beautiful rasping rim or circular toothed saw;—renewed moreover, during every moult when the shell & animal increases in size, & as the peduncle has great power to lengthen & shorten & twist itself about, I cannot doubt if you were to fix a young Lithotrya at the bottom of a deep hole of the diameter of a pin or straw, during growth the animal w^d be enabled to enlarge it to any extent. I confess I am quite puzzled by Clitia; it appears to me from your specimens, (which I must hereafter further examine) that the whole of the corrosion is effected round the margin of the base; that is, that no corrosion or wear goes on except round the growing basal edges— did you come to this conclusion? I cannot doubt that the shell is so fixed that it cannot move; certainly there are no sharp points on basal membrane as I have formerly examined it under high power.— Does not your fact of the Modiola show that the action is effected by solution, or at least not mechanically.—⁷

You ask me about Goodsir’s male Balanus; it is quite a mistake— his male Balanus is a female crustacean allied to Bopyrus & his parasite is the male of this female.—⁸ But now comes the odd case, I have found two genera of cirripedes with males separate & parasitic on the females;⁹ in these cases I am sure there can be no mistake, though I will not take up your time with details.—

I have not yet!! looked at Alcippe for ever since writing last to you, my two-hour-per day-work has been occupied with a tiresome set of fossils.— I have the curious Alepas squalicola sent me from Copenhagen,¹⁰ but I have not looked at it yet.—

Yours very sincerely | C. Darwin