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Darwin Correspondence Project

From Raphael Meldola   24 March 1873

21 John Street, | Bedford Row, W.C.

March 24th. 1873

Dear Sir,

At a meeting of the Entomological Society last Monday evening Mr. Bates put your questions on ocelli to the Members present.1

I looked through my collection of butterflies to-day to see if any difference existed in the ocelli of the two sexes of any species possessing this marking. The only difference I could find was in our common Satyrus Tithonus.2 The ocellus in this species consists of a black spot with two central white dots. In the ♂ the dots are situated one beneath the other thus


In the ♀ the dots are much more obliquely placed—


The difference is a trifling one but so far as I know has not been observed before. It is moreover a constant sexual character in all specimens that have come under my notice.

My time is so much engaged at present that my researches in mimetic analogy & protective resemblance progress but slowly. The results I have arrived at I propose to publish in a series of papers. The first instalment will appear in the next part of the Proc. Zoo. Soc.3

I must apologise for troubling you with so small a matter but every natural fact has a meaning for those who can & will decipher it.

Yours respectfully, | R. Meldola.

C. Darwin Esq. M.A, F.R.S.

P.S. I notice with pleasure the recent influx of papers on subjects connected with evolution to the Royal Society.

CD annotations

2.2 The only … Tithonus. 2.3] double scored pencil
Top of letter: ‘Descent of Man’ pencil, circled pencil; ‘Ocelli’ red crayon


At a meeting of the Entomological Society of London on 17 March 1873, the vice-president, Henry Walter Bates, asked on CD’s behalf for information on ‘sexual differences in insects furnished with ocellated spots’ (Proceedings of the Entomological Society of London (1873): xiii). In Descent 2d ed., CD expanded his discussion of the extreme variability of the ocelli on the wings of Lepidoptera, admitting that the presence of so ornamental a feature in both sexes was a problem for the theory of sexual selection; he referred to information received in response to this request although he did not name Meldola (Descent 2d ed., p. 320 and n. 25).
Satyrus tithonus is a synonym of Pyronia tithonus (the gatekeeper butterfly).
Meldola had read a paper on variable protective colouring in insects at the Zoological Society of London in February 1873; it was published later in the year (Meldola 1873). No further parts were published. For CD and Meldola’s earlier correspondence on the subject, see Correspondence vol. 20.


Gives some information on variation of ocelli between sexes in butterfly species.

Proposes publishing a series of papers on mimicry.

Letter details

Letter no.
Raphael Meldola
Charles Robert Darwin
Sent from
London, John St, 21
Source of text
DAR 89: 83–4
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 8821,” accessed on 25 June 2019,

Also published in The Correspondence of Charles Darwin, vol. 21