From R. H. Tiddeman   23 March 1871

Dear Sir

I take the liberty of communicating to you a fact which I think may be of some interest to you. I have been lately reading with much pleasure your ‘Descent of Man’ and was talking about it to an unscientific friend of mine at Lancaster last Sunday. Amongst other subjects I was speaking of reversion and mentioned the occasional existence of supernumerary mammæ in women— He said “You know Charlie—”¹ alluding to a young man in North Lancashire with whom I have only a slight acquaintance, “he has two pairs”   He said that he had often seen them when bathing with him that the second pair were below the usual pair about a finger’s length, that they were altogether similar except in size, being smaller   In other respects he is a well made man and belongs to a good looking family. It would be interesting to know whether this peculiarity exists in other members of the family. Unfortunately from my acquaintance only being very slight and also from the delicacy of the subject I am unable to glean further particulars. I presume such a structure in man, where utility as a preservative would be wholly excluded, might be referred with greater confidence to reversion than the previously recorded cases in women

Permit me to take this opportunity of expressing my gratitude for the great pleasure and interest which I have found in your works

With the greatest respect | I am yours faithfully | R H Tiddeman H.M. Geological Survey

Charles Darwin Esq^re. FRS etc