From Roland Trimen 31 December 1867
71, Guildford Street, | Russell Square | London, W.C.
31st. December, 1867.
My dear Mr. Darwin,
In a wilderness of ocelli,1 I have stupidly forgotten the exact nature of the information which you indicated as requisite. Am I right in thinking that you wanted one or two instances of gradation in the developement of ocellated spots in the same species? or, if that cannot be found, of gradations from a simple spot to a many-ringed ocellus in closely-allied species?2
With reference to the relative abundance of the sexes, which is apparently very generally in favour of the ♂ in butterflies, I find that Wallace (Trans. Linn. Soc. XXV “On the Papilionidæ of the Malayan Region”) notes that the ♀s of Ornithoptera Crœsus (peculiar to the island of Batchian) were “more plentiful” than the ♂s.3 This is a case in which there is a very wide difference between the sexes, the ♂ being splendidly coloured with shifting green and orange on a black ground, while the ♀ is (like those of all the nearly-allied species) dull-brown with whitish markings.
Mr. Waterhouse Junr.4 has kindly given me the name of the Cape Beetle which I mentioned to you. It is Peritrichia cinerea, a small, long-legged Lamellicorn belonging to the characteristic S. African Pachycnemidæ. The ♂ is slaty-grey clothed with whitish hairs, and the ♀ rufous-brown with pale-yellowish hairs. Though the ♀ has been described as a distinct species (P. proboscidea), I found that the sexes were placed together as one species in the British Museum collection, but without the knowledge that they were sexes of the same insect.5
I have so often taken the two in copulâ that you may rely on the correctness of this observation.
I will not forget to send you any points of importance which appear to bear upon your present special subject of research, if I am fortunate enough to chance upon them.
With my respects to Mrs. Darwin, I remain | Very faithfully yours, | Roland Trimen.
C. Darwin Esqre.
CD annotations
Footnotes
Bibliography
Columbia gazetteer of the world: The Columbia gazetteer of the world. Edited by Saul B. Cohen. 3 vols. New York: Columbia University Press. 1998.
Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.
Poulton, Edward Bagnall. 1920. Roland Trimen, 1840–1916. Proceedings of the Royal Society of London, Series B 91: xviii–xxvii.
Wallace, Alfred Russel. 1864b. On the phenomena of variation and geographical distribution as illustrated by the Papilionidæ of the Malayan region. [Read 17 March 1864.] Transactions of the Linnean Society of London 25 (1865–6): 1–71.
Summary
On ocelli.
Sexual differences and proportion of sexes in butterflies.
Coleoptera.
[See Descent 1: 310; 2: 132.]
Letter details
- Letter no.
- DCP-LETT-5744
- From
- Roland Trimen
- To
- Charles Robert Darwin
- Sent from
- London, Guildford St, 71
- Source of text
- DAR 82: A30–1
- Physical description
- ALS 4pp †
Please cite as
Darwin Correspondence Project, “Letter no. 5744,” accessed on 24 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-5744.xml
Also published in The Correspondence of Charles Darwin, vol. 15