To Andrew Murray   5 May [1860]¹

My dear Sir

I must thank you again for your kindness,—or rather I should say generosity. I find that I did not understand you about “prepotency”;² I thought that you referred to fertility,— with respect to resemblance I fully believe there is often the greatest difference both in crossed species (as has been proved) & in crossed varieties in impressing likeness on offspring. I do not yet understand about marrying hermaphrodite opposites.

It is very kind in you to put in a note about the “abominable animal”—³ the case has been struck out in my 2^d. Edition,—the main fact left in as illustration of diversified habits.—

With respect to the cave animals, reflect on the cave-Rat, the fish Amblyopsis & Astacus in America—the Proteus in caves of Europe,⁴ & you will admit that on creation doctrine, there has been surprising diversity for such similar habitations.— Thank you very much for famous list of references.—

I blundered about the Ant-insect— I remembered that some were blind & thought it was Paussus. What a noble thing would natural science be, if all its followers were actuated by your kind & liberal spirit. If ever I feel inclined to write spitefully about an antagonist, I will try & remember & learn a lesson from you, my antagonist.

My dear Sir | Yours very sincerely | Charles Darwin

Since last writing I have heard from capital Geologist Count Keyserling & he makes no difficulty about imperfection of Geological Record.—⁵