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Darwin Correspondence Project

To Edward Blyth   [after July 1868]1

Please return this paper

I have said in my M.S. on your authority, (but I suppose it is a blunder on my part?) that the F. of Euplocomus has spurs.2 I see in Jerdon (III. p. 541) that the Fs. of Galloperdix have spurs, but fewer than in the Male3

[There are different types of Euplocamus (as admitted by Sclater).4 In one of them, consisting of the “small fire-back pheasants” (Acomus), the females bear spurs, but not in the other types of that group, as the “great fire-backs,” the Kallij-pheasants, the silver, the Swinhoe’s, and the Sha’n pheasants.5 Acomus comprises the Phasianus erythropthalmus, Raffles, of Malacca and Sumatra; and a “Duplicate race in Borneo.6 The ♀ of Galloperdix is spurless.]

In the Indian Field (1858. p. 52) you say that both sexes of Passer castanopterus 7 “may be said to approximate in plumage to the female of the common sparrow, with a spot of bright yellow on the breast & some maronne at the shoulder of the wing.”8 I also enclose an extract from one of your letters on 2 other species of Passer: In birds I know of no other case like that of Passer montanus, in which the young, as well as the adults of both Sexes, are clad in a plumage analogous to that characteristic of the adult male only of P. domesticus, while in other sparrows, as P. petronius, P. flavicollis, &c, both sexes retain the colouring analogous to that of the female and young of P. domesticus.9

Now will you consider whether I may say that the F. of the common Sparrow is closely analogous in plumage to both sexes of any of the above species.

[Yes. I think that you may fairly do so. But refer to the Ibis for April 1868, p. 205–6, with coloured figure published at the end of July No, & you will find another remarkable instance in Petronia brachydactyla, Tristram, of Palestine in which also the sexes are alike—clad in plumage analogous to the ♀ of common sparrow.10]

I see in Ibis vol. 6. p. 65 that the young Male of Petrocincla Cyanea acquires some blue as a nestling.11 How are the adult & young Females coloured? Is not this case analogous to that of Orocetes erythrop:?12 And are not these birds allied?

[In habit, Orocetes is a forest thrush, Petrocincla (QQQQ’s Petrocossyphus) a rock thrush; but as thrushes they are akin, & in both groups the males are chiefly blue, the females brown; now, in the first or nestling dress of the males, those feathers which are not shed and renewed at the first moult, viz. the primaries and rectrices, are blue-edged as in the adults in ♂, brown-edged as in the adult in ♀—13]

What does Swinhoe (Ibis. 1866 p. 296) mean by saying of the full grown young of Urocissa Cerulea that they have “a few of the occipital feathers tipped with violet: Darwin again!”?14

[Swinhoe evidently refers to the resemblance in this instance of the occipital feathers of the young (or distinguished from the adult) of Urocissa cærulea to what is seen in adults of U. sinensis, U. occipitalis, and U. magnirostris—three very nearly allied races.15 In the young of U. occipitalis (and probably of the others also) the occipital pale colouring referred to is more developed in the young than in the adult.]

CD annotations

2.1 I have … spurless. 3.7] crossed ink
2.3 have spurs] ‘(p. 6 A.)’16 above ‘spurs’, blue crayon
3.1 There are … spurless. 3.6] scored ink
4.1 In the Indian … above species. 6.2] crossed ink
7.1 Yes.... sparrow. 7.4] scored ink
9.1 In habit … ♀— 9.5] scored ink
11.1 Swinhoe … in the adult. 11.5] scored ink


The date is established by the reference to the July 1868 issue of Ibis.
CD refers to the manuscript of the section on birds for Descent; he began writing this section on 17 May 1868 (see ‘Journal’ (Correspondence vol. 16, Appendix II)). CD left a space after each question for Blyth’s answers. Blyth’s answers are reproduced here in square brackets. Blyth made some alterations to CD’s text; he corrected CD’s spelling of Euplocamus, the genus of small fireback pheasants.
Thomas Claverhill Jerdon wrote that females of the genus Galloperdix (spurfowls) had one or two spurs (Jerdon 1862–4, 2: 541). In Descent 2: 46, CD cited Jerdon, but wrote that females had only one spur.
Euplocamus (family Phasianidae) was the genus of gallopheasants, now replaced by the genus Lophura. For Philip Lutley Sclater’s division of the genus into five sections, see Sclater 1863, pp. 118–21.
The ‘great fire-backs’ included Euplocamus vieilloti ( now Lophura ignita rufa, Viellot’s crested fireback), E. ignitus (now L. ignita ignita, the lesser Bornean crested fireback), E. nobilis (now L. ignita nobilis, the greater Bornean crested fireback), and E. swinhoii (Swinhoe’s pheasant; now L. swinhoii). On Kalij pheasants, see the letter from Edward Blyth, [before 25 March 1868] and n. 16 (see also Sclater 1863, p. 121). The silver pheasant was E. nycthemerus (now L. nycthemera). Blyth was mistaken in including the Shan pheasant, which was not a species of Euplocamus; it was Phasianus amherstiae (now Chrysolophus amherstiae, Lady Amherst’s pheasant).
Included in the section Acomus were Euplocamus erythrophthalmus (now Lophura erythrophthalma erythrophthalma, the Malayan crestless fireback pheasant), and E. pyronotus (now Lophura erythrophthalma pyronota, the Bornean crestless fireback pheasant). In Descent 2: 46, CD cited Blyth for information on spurs in females of E. erythrophthalmus.
Blyth deleted ‘castanopterus’ and wrote ‘flavicollis’ above. Passer castanopterus is the Somali sparrow; P. flavicollis is now P. pyrrhonotus (the Sind jungle sparrow).
[NEED TO FIND COPY OF the Indian Field ONLY ONE IN BL BUT SEEMS NOT TO HAVE ALL 1858. HAVE PUT IN BL QUERIES]. ‘Maronne’ is evidently a reference to the colour maroon.
See letter from Edward Blyth, [before 25 March 1868] and n. 33.
Blyth refers to Tristram 1865–8, pp. 205–6. In the bound volume, the illustration of Petronia brachydactyla (the pale rock sparrow) is facing page 204.
CD refers to Wright 1864, p. 65, in which the author notes that male nestlings of Petrocincla cyanea (now Monticola solitarius, the blue rock thrush) can be distinguished by their blue wing-coverts.
Blyth crossed out ‘Erythrop’ and wrote ‘erythrogaster’ above it. Orocetes erythrogaster is now Monticola cinclorhynchus (the blue-capped rock thrush).
In Descent 2: 219–20, CD discussed plumage differences in these thrushes and cited the information from Wright 1864, p. 65. Blyth used an upside-down female symbol instead of a male symbol here.
CD quotes from Robert Swinhoe’s description of Urocissa caerulea (the Formosan magpie) in Swinhoe 1866, pp. 296–7.
Urocissa sinensis is now U. erythrorhyncha (the blue magpie); U. occipitalis and U. magnirostris are now considered subspecies of U. erythrorhyncha.
The page reference is presumably to CD’s manuscript (see n. 1, above).


Questions from CD related to bird plumage and sexual differences, with answers by EB.

Letter details

Letter no.
Charles Robert Darwin
Edward Blyth
Sent from
Source of text
DAR 84.2: 183, 187, 187v
Physical description
3pp ††

Please cite as

Darwin Correspondence Project, “Letter no. 6532,” accessed on 27 April 2017,

Also published in The Correspondence of Charles Darwin, vol. 16