To Albert Charles Lewis Gotthilf Günther   7 December [1867]1

Down. | Bromley. | Kent. S.E.

Dec 7

My dear Sir

I enclose, as you desired, my photograph. Allow me to thank you cordially for your great kindness in giving me so much information, which is of real value to me.2 Should any cases occur to you of well-marked sexual differences in snakes, batrachians, or lizards (about which I forgot to ask) will you have the kindness to make a memorandum on the subject.3 I think I remember that the males of certain lizards in S. America had a scarlet throat; but this may have been an error.4 In the Zoolog. gardens the keeper shewed me the males & females of the rattle-snake, & they differed considerably in colour;—the males being much more yellow.5 He gave me positive evidence of the sexes, & said all that he had seen presented the same difference. I have told my publisher to send a copy of my book on “Variation &c” which will be published in 2 or 3 weeks, to you at the Brit. Museum; but I much fear it will contain very little that can interest you6

Believe me | my dear Sir | yours very sincerely | Charles Darwin

LS

1
The year is established by the relationship between this letter and the letter from A. C. L. G. Günther, 19 December 1867.
2
No letter from Günther requesting CD’s photograph has been found in the Darwin Archive–CUL. CD probably saw Günther during his visit to London from 28 November until 7 December 1867 (CD’s ‘Journal’ (Correspondence vol. 15, Appendix II)). The information provided by Günther probably included details of sexual differences in fish as reported extensively in Descent.
3
Günther is cited on sexual differences in species of batrachians and reptiles in Descent, chapter 12. See also letter from A. C. L. G. Günther, 19 December 1867. CD’s notes of information from Günther for Descent about snakes, batrachians, and fish are in DAR 82.
4
The lizard species has not been identified. However, CD cited the blue, green, and coppery-red throat pouch of the Chilean lizard Proctotretus tenuis (now Liolaemus tenuis) as an example of males being more brightly coloured than females in Descent 2: 37. For descriptions of the lizards collected in South America by CD, including information on sexual dimorphism, see Reptiles. For CD’s notes on the lizards he collected in South America, see R. D. Keynes ed. 2000.
5
CD refers to the gardens of the Zoological Society of London in Regent’s Park, London. The information on the rattlesnake is given in Descent 2: 29. For names of some contemporary keepers, see Scherren 1905, pp. 127, 143. CD had visited London from 28 November until 7 December 1867 (see n. 2, above).
6
CD refers to John Murray and Variation, which was published on 30 January 1868 (CD’s ‘Journal’ (Correspondence vol. 15, Appendix II)).

Please cite as “DCP-LETT-5710,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-5710