1 On 4 July, Orion had written in regard to Clemens’s “Brace of Brief Lectures on Science”: “I had some notion in relation to the scientific lectures to comment editorially, taking extracts from the books to verify your statements if you will let me know where they came from. I like them, but people will think you made the whole thing, maybe—text as well as commentary” (CU-MARK). Orion did in fact comment, drawing his information from Louis Figuier’s Primitive Man (1870), which had been reviewed and extracted at length in Chamber’s Journal for 13 August 1870, Clemens’s source (21 June 71 to Bliss, nn. 2, 4; OC 1871; “Our Earliest Ancestors,” Chambers’s Journal of Popular Literature, Science, and Art 47:521–24).