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Darwin Correspondence Project

To Alfred Newton   19 January [1867]

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

Jan 19.

My dear Sir

Will you have the kindness to give me some information on one point? Not long since I was speaking to Mr Wallace about his mimetic butterflies,1 & I told him of the case of the Rhynchœa, of which the female is more beautiful than the male, with the young resembling the latter.2 He answered me that you at Nottingham had advanced this or some such case, & that you had simply explained it by the male being the incubator.3 I should be extremely obliged if you wd give me any information on this head & allow me to quote you. The subject interests me greatly, as in the 4th Edit. of the Origin I gave the obvious explanation of female birds not being gaudily coloured &c on account of their incubating;4 I knew then of the Rhynchœa but passed over the case from not having space & from its appearing to me quite inexplicable.

I hope that you will forgive me troubling you & believe me my dear Sir | yours sincerely | Charles Darwin

P.S. As I am writing, I will ask one other question, for the chance of your being able to answer it: Does the male black Australian swan, or the black & white S. American Swans, differ from the females in plumage? ie in the intensity of the black, or in the amount of black in the black-necked species?5


CD may have seen Alfred Russel Wallace when he was in London from 22 to 29 November 1866; see Correspondence vol. 14, Appendix II. See also ibid., letter from A. R. Wallace, 19 November 1866.
CD refers to a species of painted snipe, Rhynchaea (now Rostratula; see Birds of the world). CD discussed secondary sexual characteristics in three species of Rhynchaea in Descent 2: 202–3.
Wallace and Newton attended the 1866 meeting of the British Association for the Advancement of Science in Nottingham (Report of the thirty-sixth meeting of the British Association for the Advancement of Science 1866). In Descent 2: 200, CD wrote that it was Wallace who ‘first called attention to the singular relation … between the less bright colours of the males and their performing the duties of incubation’; he cited [Wallace] 1867a.
See Origin 4th ed., p. 241.
CD saw black-necked swans in South America while on the Beagle voyage (see Journal of researches, pp. 133, 346).


Birds of the world: Handbook of the birds of the world. By Josep del Hoyo et al. 17 vols. Barcelona: Lynx editions. 1991–2013.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Journal of researches: Journal of researches into the geology and natural history of the various countries visited by HMS Beagle, under the command of Captain FitzRoy, RN, from 1832 to 1836. By Charles Darwin. London: Henry Colburn. 1839.

Origin 4th ed.: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 4th edition, with additions and corrections. By Charles Darwin. London: John Murray. 1866.


Seeks explanation of the case of the Rhynchaea, of which the female is more beautiful than the male, with the young resembling the latter. Wallace has told CD that at Nottingham AN explained this by the male being the incubator.

Does the male black Australian swan, or the black and white S. American swan, differ from the female in colour of plumage?

Letter details

Letter no.
Charles Robert Darwin
Alfred Newton
Sent from
Source of text
DAR 185: 87
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5371,” accessed on 25 October 2021,

Also published in The Correspondence of Charles Darwin, vol. 15