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Darwin Correspondence Project

To Albert Günther   12 May [1868]1

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

May 12th

My dear Dr. Günther

You were so kind as to say that I might ask you some questions.— I have roughly written out my short discussion about secondary sexual differences of fishes, chiefly from your information; & some points have occurred to me about which I shd be grateful for answers.—2 I enclose my queries; & I hope & think they will not cause you great trouble, for “yes” or “no” or “do not know” will answer most of them. Will you write at back of my paper & put corresponding numbers to answers?—3

Be so, kind as to give enclosed note to Mr Ford, when next at the Museum, it is about figures of fishes.—4

When I saw you in London, you said that you would run down here. We shall be most happy to see you at anytime, & you can come down on the Saturday evening or Sunday morning, whichever suits you best, & sleep here & in all probability I can send you in some vehicle as early as you like on Monday morning to the Station.— Bromley is 6 miles distant; but Orpington, (a new station on S. E. Railway) is only about 3 miles distant, though more distant from London.—5

I shd like to hear whenever you have time & inclination to come here, for this reason, that I may be idle in the morning, for if I do my full morning’s work, I am generally dead tired in the evening,— my usual state being one of fatigue.—

With most sincere thanks for all the very great kindness which you have shown towards me, pray believe me | Yours very sincerely | C. Darwin


(1) Am I right in supposing that the two sexes of Callionymus are described by Yarrell as C. Lyra (the male) and C. dracunculus as the female? Yarrell says nothing about the first dorsal fin being brightly striped in C. Lyra which, if I am not mistaken, you said was the case.6

(2) Am I right in believing that both sexes of some species of Blennius have a crest, & that neither sex is thus furnished in B. pholis?7

(3) Yarrell speaks in a manner which makes me suppose that perhaps both sexes of some Gasterostei are crimson beneath. Is this the case? I see that neither sex is crimson beneath in some species.8

(4) Are the sexes known to differ in Colour in any other species of Labrus, besides L. mixtus?9

(5) Cuvier says that some species of Gobius make nests;10 now do any of these species differ at all sexually in colour?

(6) Do any of those fishes which deposit their eggs within the mouth or within the marsupial sac of the male differ sexually in colour?

(7) are Crenilabrus massa and melops, which build nests, brightly coloured species; or is it known that they become brighter during the breeding season?11

(8) Do any other genera besides crenilabrus, gobius & gasterosteus build nests.12

(9) M. Carbonnier maintains that the females of all fishes grow to a larger size than the males.13 Is there any truth in this? You told me of some Cyprinodontae in which this is the case. Do you believe that the females of many kinds of fish are larger than the males? Or do you know of any cases in which the males are larger than the females?


The year is established by the relationship between this letter and the letter from A. C. L. G. Günther, 13 May 1868.
For CD’s discussion of secondary sexual characters in fish, see Descent 2: 1–23. Günther had sent CD information on Cyprinodont fish in his letter of [late December 1867 or early January 1868] (Correspondence vol. 15). The two men had probably also met at the British Museum in London in March: see letter to A. C. L. G. Günther, 23 March [1868], n. 2.
See enclosure, and letter from A. C. L. G. Günther, 13 May 1868.
The note has not been found. George Henry Ford, an artist at the British Museum, provided the illustrations for chapter 12 of Descent, on fish, amphibians, and reptiles.
Günther apparently did not visit Down until 22 to 24 January 1870 (Emma Darwin’s diary (DAR 242)). Orpington was on the Chislehurst to Sevenoaks extension of the South Eastern Railway; the branch opened on 3 March 1868 (Cox 1988, p. 48).
CD refers to William Yarrell and his History of British fishes (Yarrell 1836, 1: 261–8). Yarrell mentioned the suspicion that Callionymus lyra (the gemmeous dragonet) and C. dracunculus (the sordid dragonet) were male and female of the same species in ibid., p. 266–7. Callionymus dracunculus is now a ‘suppressed’ name, synonymous with C. lyra (Pauly 2004, p. 59). For Günther’s discussion of C. lyra, its misclassification as two species, and its appearance, see Günther 1859–70, 3: 139–41. CD gave a reference to this discussion in a note dated 21 June 1867 (DAR 82: B5). See also Descent 2: 7–9.
For crested and uncrested blennies, including Blennius pholis, see Yarrell 1836, 1: 223–38. Yarrell makes no distinction between male and female blennies. CD remarked that in some species of blenny, only the male was crested, and in some, both sexes were crested, in a note dated 21 June 1867 (DAR 82: B5–6). Blennius pholis is a synonym of Lipophrys pholis.
Gasterosteus is a stickleback genus. Yarrell in Yarrell 1836, 1: 81, comments of the first three species he lists (Gasterosteus trachurus, G. semiarmatus, and G. leiurus), ‘Some exhibit various shades of crimson and purple; but these colours are more frequent in males than females’. These three names are all synonyms of G. aculeatus. Yarrell also describes G. pungitius (now Pungitius pungitius) and G. spinachia (now Spinachia spinachia) as having no red coloration (Yarrell 1836, 1: 85–9).
CD described the coloration of Labrus mixtus, the red wrasse, in Descent 2: 9. Günther had shown him specimens in June 1867 (see DAR 82: B6, note dated 21 June 1867).
CD refers to Georges Cuvier and Cuvier 1829–30, 2: 242. Gobius is a genus of gobies.
Crenilabrus massa (the grey wrasse) is now Symphodus cinerea; C. melops (the corkwing wrasse) is now Symphodus melops (Pauly 2004, p. 210).
CD mentions the nests of Crenilabrus, Gobius, and Gasteosterus in Descent 2: 19–20.
CD cited Pierre Carbonnier’s view that in almost all fish species, the females were larger than the male, as quoted in the Farmer 1868, p. 369, in Descent 2: 7.


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

Cox, Dorothy. 1988. The book of Orpington. 2d edition. Buckingham: Barracuda Books.

Cuvier, Georges. 1829–30. Le règne animal distribué d’après son organisation, pour servir de base a l’histoire naturelle des animaux et d’introduction a l’anatomie comparée. New edition, revised and augmented by P. A. Latreille. 5 vols. Paris: Déterville and Crochard.

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

Günther, Albert Charles Lewis Gotthilf. 1859–70. Catalogue of acanthopterygian fishes in the collection of the British Museum. 8 vols. London: by order of the Trustees.

Pauly, Daniel. 2004. Darwin’s fishes. An encyclopedia of ichthyology, ecology, and evolution. Cambridge: Cambridge University Press.

Yarrell, William. 1836. A history of British fishes. 2 vols. London: John Van Voorst.


Sends some questions on secondary sexual differences of fishes [missing], which he hopes AG will look over.

Invites AG to come to Down.

Encloses queries on sexual differences and nest-building habits of fish.

Letter details

Letter no.
Charles Robert Darwin
Albrecht Carl Ludwig Gotthilf (Albert) Günther
Sent from
Source of text
Shrewsbury School, Taylor Library (Gunther letters 2); DAR 82: B21–2
Physical description
4pp encl 3pp

Please cite as

Darwin Correspondence Project, “Letter no. 7186,” accessed on 15 August 2020,

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