The year is established by CD’s reference to having received the first instalment of Rolle 1866, which was issued in 1865 (see n. 2, below). See also Correspondence vol. 14, letter from Friedrich Rolle, 28 January 1866, in which Rolle states that he sent the first part of Rolle 1866 to CD the previous summer. The copyist has written ‘1863’ in error.

Rolle’s Der Mensch (Rolle 1866), a study of the development of human society in the light of Origin and recent discoveries in geology, was published in five parts; the first part was published on 1 May 1865 (Börsenblatt für den Deutschen Buchhandel und die mit ihm verwandten Geschäftszweige 32 (1865): 954), the second and third parts were issued on 17 November 1865 (ibid. 32 (1865): 2634), and the fourth and fifth parts were issued on 15 January 1866 (ibid. 33 (1866): 103). CD’s annotated copy of Rolle 1866 is in the Darwin Pamphlet Collection–CUL. CD cited Rolle 1866 in Descent 1: 4 n. as one of several works that had concluded that the human race was ‘the co-descendant with other species of some ancient, lower, and extinct form’ (ibid., p. 3). CD had begun a correspondence with Rolle, a German geologist and palaeontologist, in 1862, after Rolle sent him a copy of his popular exposition of CD’s theory (Rolle 1863; see Correspondence vol. 10). For Rolle’s work in popularising CD’s views, see Correspondence vol. 11, letter from Friedrich Rolle, 26 January 1863, and letter to Friedrich Rolle, 30 January [1863].