From Albert Günther   13 May 1868

Brit. Mus.

13.5.68

My dear Sir

I send the answers;1 if they are in any way deficient, or if you can think of any other questions, remember that I have the greatest pleasure in seeing the few facts I have observed, utilized by you. I have not forgotten your wish about the modification of colors in Snakes, but I wait until I take up for further study the family in which the colors vary, which will be before long.2

I send you also the two proofs of fish which I promised, the paper itself will be published in a few weeks, when I shall send it to you.3

I have given the note to Ford, he will attend to your woodcuts during the course of next month.4

Many thanks for your kind invitation which I shall follow as soon as I have finished my portion of the ‘Zoolog. Record’.5

Beside this work I am studying at present the development of the Axolotl, which has bred in my aquarium.

Yours most truly | A Günther

[Enclosure]

ad 1.

Yes.— The first & second dorsal fins are brightly spotted & banded in the male.— Get from one of the libraries the 3d volume of my “Catalogue of Fishes”, where the subject is more fully treated of on p. 139–141. You will find there described numerous other species of Callionymus, with their sexual differences indicated.6

ad 2

I have found the crest to be the character of the male in Blennius pavo (Catal. of Fish III. p. 221). Bl. pholis has never a crest. A similar observation I have made in the Blennioid genus, Salarias, (Catal. of Fish III. p. 240).7 Our knowledge of other species is very incomplete at present, owing to the difficulties in ascertaining the sex in small & badly preserved examples. But this I can maintain at present, there are species in these two genera, in which the crest is a sexual character; others in which both sexes are provided with a crest; others in which the crest is absent in both sexes.

ad 3

I can speak, from experience, only of G. aculeatus = trachurus = liurus.8 In this species I have only the male seen with bright colors, the female never.

ad 4

L. mixtus is the most striking example known; I should infer from analogy that the males of other species are also more brightly colored, but you cannot be certain about this from examining spec. in spirits.9

ad 5

Nothing is known on this subject; if they differ, the differences are very slight.10

Ad 6

Not those which carry the young in the mouth. I believe the Hippocampi-males are more brightly colored than the females. But in Solenostoma it is the female which carries the eggs in the pouch, & this is most vividly colored. (see Günth. Fish. of Zanzibar p. 138. pl. 20 figs 2 & 3, both females).11

Ad 7

Yes; it is not positively known, but I should think they have a “wedding-dress” (I don’t know whether the word is admissible)

Ad 8

Many Siluroids, for instance Callichthys, of which we have a nest in the Museum

Ad 9

I do not recollect one case in which the male is larger.12

CD annotations

Enclosure
1.0 ad 1. … indicated. 1.4] crossed ink
2.0 ad 2 … sexes. 2.7] crossed ink
3.0 ad 3 … never 3.2] crossed pencil
4.0 ad 4 … spirits. 4.3] crossed pencil, ‘Labrus’ added pencil
9.0 Ad 9 … larger. 9.1] crossed pencil
Bottom of enclosure: ‘Gunther on Fishes | Capital | The ♀ Pipe Fish which carry eggs & so depart from type by brighter colours is wonderfully good— for she wd require protection. | Ask about Callichthys which builds whether males take share in building.’ pencil
1
For CD’s questions, see the letter to Albert Günther, 12 May [1868].
3
See Correspondence vol. 15, letter from A. C. L. G. Günther, [late December 1867 or early January 1868] and n. 4. The proofs were probably for plates 86 and 87 of Günther 1864–6, a paper on South American fish published in the Transactions of the Zoological Society of London. Plates 86 and 87 showed the peten molly, Mollienesia petenensis (a questionable synonym for Poecilia petenensis: FishBase (internet resource), consulted 15 September 2005), and the green swordtail, Xiphophorus helleri, species in which the differences between male and female were strongly marked. The part containing Günther’s paper was published in 1868; CD’s lightly annotated copy is among the unbound journals in the Darwin Library–CUL. CD used the engravings of Xiphophorus helleri, male and female, in Descent 2: 10, and cited Günther 1864–6 in ibid., p. 9 n. 14.
5
See letter to Albert Günther, 12 May [1868] and n. 5. Günther was the founding editor of the Zoological Record, or Record of Zoological Literature, and worked on the sections on fish and reptiles (Gunther 1975, p. 289).
6
Günther refers to Günther 1859–70. See letter to Albert Günther, 12 May [1868] and n. 6. CD cited the third volume of Günther 1859–70 for information on Callionymus in Descent 2: 9.
7
CD cited Günther 1859–70, vol. 3, for information on blennies and an ‘allied genus’ in Descent 2: 12–13. Blennius pholis is a synonym of Lipophrys pholis. Blennius pavo, the peacock blenny, is now Salaria pavo. In Günther 1859–70, 3: 240, Günther remarked of the genus Salarias that since he had found the crest to be a male character in other genera, it was possible that some specimens that had been classified as uncrested species would turn out to be females of apparently crested species. Salaria and Lipophrys are both in the family Blenniidae. Salaria and Salarias are both current genera.
10
See letter to Albert Günther, 12 May [1868] and n. 10. In Descent 2: 20, CD said that gobies were not known to differ in colour.
11
CD repeated Günther’s information on Hippocampus and Solenostoma in Descent 2: 21–2. Günther refers to Playfair and Günther 1866. Solenostoma is now an invalid synonym of Solenostomus.
12
CD reported Günther’s statement that he did not know of any species of fish in which the males were larger than the females in Descent 2: 7.

Please cite as “DCP-LETT-6170,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-6170