To Albert Charles Lewis Gotthilf Günther 7 December 1
Down. | Bromley. | Kent. S.E.
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
Sends his photograph.
Asks for any information of well-marked sexual differences in snakes, batrachians, or lizards. The rattlesnakes at the Zoological Garden differ considerably in colour.
Please cite as
Darwin Correspondence Project, “Letter no. 5710,” accessed on 24 January 2017, http://www.darwinproject.ac.uk/DCP-LETT-5710