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Darwin Correspondence Project

From Roland Trimen   18 November 1869

Colonial Office, | Cape Town.

18th. November, 1869.

My dear Mr. Darwin,

I am very much obliged for your “Notes on the Fertilization of Orchids”, received a fortnight ago, and for your kind notice of my observations in the paper.1 I have examined several fresh Ophryds since my return hither,2 but have not observed any contrivance that seems to require special notice.

What an extraordinary and unique device you notice in Coryanthes!3 There really seems to be no limit to Nature’s versatility: it is impossible to conjecture anything too unusual or unlikely for her to accomplish. Every organism seems to be perpetually on the qui vive for the slightest chance of bettering its position, and it is difficult to separate the fact of this constant fitness and aptitude for making the utmost of opportunities from the idea of conscious and deliberate intent and action. One certainly cannot say at what point in the scale intellectual action or purpose absolutely ceases.

I have not forgotten your query about Baboons; but no person that I have spoken to on the subject can say from observation that males fight for possession of females, though at the same time I notice that no one seems to think such a proceeding at all unlikely.4

Mention of sexes reminds me that I made a note for you respecting the assembling of many ♂s of Sphinx Convolvuli about a single ♀.5 Unfortunately, I cannot lay my hand on it, so as to refer to the work in which I noticed the case, but I am quite sure of the fact’s being on record, and that it was observed in some part of England.

Among Moths whose underside of the wings exceed the upperside in beauty of marking and colouring, I find the South-American Geometræ belonging to the genus Erateina of E. Doubleday. Of those figured (in Trans. Ent. Soc. Lond., New Series, vol. V, pl. XV & XVI), the more striking in this respect are E. Regina, E. Margarita, and E. obscura. 6 In all these the upper surface is brownish or fuscous with a few white markings, while the under surface is elaborately varied with white, red, & chestnut-red, and in E. Regina with yellow also.

About a year ago, I witnessed and made a note of a case of sexual selection in a Moth, Syntomis cerbera. The ♀ in this instance had but recently emerged from the puparium, for her wings (she was clinging to the underside of a leaf of a tall grass) were still limp and hanging downward. When I first noticed her, she was closely beset by four ♂s. One of these flew off as I approached, but the remaining three persisted in their endeavours, clustering about in constant motion, and holding on by the ♀’s back and wings. I watched them closely; and though each ♂ repeatedly contrived to clasp the extremity of the ♀’s abdomen with his own, and the ♀ remained perfectly motionless, no junction was effected. After I had watched the group for about 5 or 6 minutes, one ♂ appeared to consider it a hopeless case, for he suddenly flew off. Shortly afterwards, another ♂ also departed rather abruptly. The ♂ that remained persisted for some little time in his efforts, and at length the obdurate ♀ yielded; but the union was incomplete, for, in attempting to assume the ordinary position in line with the ♀ on the narrow grass-leaf, the ♂’s struggles occasioned a separation.

A second union, however, immediately followed, the usual position was safely taken up, and the ♀ for the first time moved her wings into their ordinary place on each side of the body. I compared this successful suitor with many other ♂s taken in the same field on the same day, and am bound to say that there was nothing in his size or colouring to entitle him to preference; but, of course, I don’t presume to compare my poor ocelli with Mrs. Cerbera’s argus eyes, and there can be little doubt that she found attractions in him to which his disappointed rivals could lay no claim.

I may mention that there was a great number of these Moths in the field; I counted 24 pairs in copulâ on the grass stems, in addition to very many individuals. The Genus Syntomis is one of the family Zygænidæ, to which our English “Burnet Moths” also belong.7

I am sorry to say that I have less time than ever for Nat. History. A cry for what is called “Retrenchment” is now prevalent, and reductions are being made in the Civil Service, the effect of which in our Office is to give me much more work without the consolation of additional pay!8 Alas that the Age of Sinecures is well-nigh passed away! In my opinion, Government ought to provide appointments with little work and decent emoluments expressly for naturalists; but it is surprising how few of the people I meet share in this view!!

Hoping that your health has improved, and with kindest regards to Mrs. Darwin and your family, I remain | Very faithfully yours, | Roland Trimen.

CD annotations

1.1 I am … England. 4.4] crossed blue pencil
6.1 About … also belong. 8.4] ‘Zygænidæ’ added blue crayon
8.2 The Genus … belong. 8.4] scored blue crayon
8.3 Syntomis] underl blue crayon
8.3 Zygænidare] underl blue crayon
9.1 I am … family, 10.2] crossed blue crayon


See ‘Fertilization of orchids’, pp. 143, 144, and 157.
Trimen left England for South Africa in May 1868; see Correspondence vol. 16, letter from Roland Trimen, 13 April 1868.
No query to Trimen on baboons has been found; however, on 27 December 1867, CD spoke to Trimen about the larger size of canines and manes in baboons of South Africa (DAR 83: 19).
In Descent 1: 311–12, CD mentioned the grouping of male moths around a female, but did not cite Trimen’s example. Sphinx convolvuli is now Agrius convolvuli, the convolvulus hawkmoth.
Trimen refers to plates for the article ‘On the genus Erateina, Doubl.; with descriptions of some new species’ (Saunders 1860). Edward Doubleday was the author of Erateina. The lower and upper surface of the three species mentioned are illustrated in plate XV, figures 3 and 3a; plate XVI, figs. 2 and 2a; and plate XVI, figs. 3 and 3a. In Descent 1: 397, CD cited Trimen for information on the wings of Erateina. The former family Geometrae corresponds roughly to the modern family Geometridae.
Syntomis cerbera (the heady maiden moth) is now in the family Ctenuchidae. The valid name for the genus Syntomis is now Amata. Burnet moths (Zygaena) are still in the family Zygaenidae.
Trimen was a clerk of the second class in the Colonial Office at the Cape of Good Hope; between 1868 and 1870, his pay increased from £190 to £220 (Colonial office list, 1868, 1869, and 1870).


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

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

‘Fertilization of orchids’: Notes on the fertilization of orchids. By Charles Darwin. Annals and Magazine of Natural History 4th ser. 4 (1869): 141–59. [Collected papers 2: 138–56.]

Saunders, William Wilson. 1860. On the genus Erateina, Doubl.; with descriptions of some new species. [Read 7 May 1860.] Transactions of the Entomological Society of London n.s. 5 (1858–61): 261–7.


Thanks CD for his orchid paper ["Fertilization of orchids", Collected papers 2: 138–56]. Comments briefly on orchids.

Discusses moths in which the wing underside is the most brightly coloured, and relates his observations on sexual selection by a moth, Syntomis.

Letter details

Letter no.
Roland Trimen
Charles Robert Darwin
Sent from
Colonial Office, Cape Town
Source of text
DAR 82: 27–9
Physical description
6pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6995,” accessed on 4 December 2020,

Also published in The Correspondence of Charles Darwin, vol. 17