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Darwin Correspondence Project

To Philip Lutley Sclater   6 January [1866]1

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

Jan 6

Dear Sclater

I know that you are one of the busiest of men, but I want to beg a little bit of information & I trust to your kindness for I do not know to whom else to apply. Mr Swinhoe writes to me of a domestic race of duck in China as perhaps descended from Anas pœcilorhyncha.2 Now do you consider this form as deserving to be called a distinct species from A. Boschas & may I quote your opinion??3

How does it differ? I suppose it has the curled tail feathers & wing-marks. Is it a native of China? I shd be versuppose it has the curled tail feathers & wing-marks. Is it a native of China? I shd be very grateful for a few lines giving me information on these heads.4

Pray forgive me troubling you & believe me

yours very sincerely | Charles Darwin

P.S. After nine months inaction from illness, I have just begun to do a little work—5


The year is established by the content of the postscript (see n. 5, below).
CD probably refers to the missing portion of the letter from Robert Swinhoe, [before 1 October 1865?] (Correspondence vol. 13); the surviving portion includes a discussion of ducks, but not of Anas poecilorhyncha, the spot-billed duck of Asia. Robert Swinhoe, the British consul in Formosa (now Taiwan), had earlier informed CD of a supposed ‘thorough race’ of duck that had developed from hybrids of the muscovy duck (Carina moschata; then also A. moschata) and the Chinese domestic duck (see Correspondence vol. 10, letter from Robert Swinhoe, 12 November 1862).
No reply from Sclater has been found; in his discussion of breeds of domestic ducks and their descent from the mallard, Anas boschas (now A. platyrhynchos), in Variation 1: 276–87, CD did not cite information from Sclater or Swinhoe.
Anas poecilorhyncha is distributed throughout Asia. Its lack of curled tail-feathers distinguishes it from A. boschas, although both species have conspicuous wing patches (Birds of the world 1: 605, 607). CD mentioned A. boschas, but not A. poecilorhyncha, in Variation.
CD recorded being ill from 22 April until December 1865 (see Correspondence vol. 13, Appendix II).


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–.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Discussion of ducks. CD asks for information on a domestic Chinese race about which Robert Swinhoe wrote to CD. Compares Chinese duck with Anas poecilorhyncha and Boschas.

Notes improvement in health.

Letter details

Letter no.
Charles Robert Darwin
Philip Lutley Sclater
Sent from
Source of text
American Philosophical Society (Mss.B.D25.311)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 4970,” accessed on 28 November 2021,

Also published in The Correspondence of Charles Darwin, vol. 14