Charles DARWIN (1809-1882), the great English naturalist. L.A. (bottom of letter cut off removing signature), November 12, [probably to botanist Gaetano Durando (1811-1892) in Algiers]; 1page in-8 (cut off top of page); in English. Letter, apparently unpublished, concerning a case of atavism (in evolutionary developmental biology: the reappearance of an ancestral trait in an individual). "My dear Sir Many thanks for your extremely kind letter. I shall be pleased to receive your book, though it is wasteful to send it. I am always interested by well-authenticated cases of atavism, so [...] at leisure send me your case. Believe me". An engraved portrait of Erasmus Darwin, Charles's grandfather, is included.