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Darwin Correspondence Project

From A. G. Butler   18 July 1871

Bankside House | Chalkwell Road | Sittingbourne | Kent

July 18th. 1871

Dear Sir

I thought I would just write to let you know that I shall not be at the Brit Mus until after the 22nd., so that it will be useless to take my notes there before that time.1

I have been looking at our specimens of Brahmæa Certhia at the B.M. & I find that, though their marginal ocelli are not so well developed as in B. Swanzyi they are shaded off so as to appear like hemispheres, they have in fact the appearance of dirty drops of water; moreover on this species the broad central band on the frontwings terminates in a circular patch shaded so as to appear almost like a ball in certain positions thus—


you will see better what I mean if you turn to my paper on Brahmæa in the Zool. Proc. for ?1867:2 Now as all these markings are rather better formed in the males than in the females I think they have been produced by sexual selection: the action on most male moths (especially of this group) when approaching the females is precisely that of a pendulum & therefore the opposite wings would alternately appear to advantage thus—


& this I think may explain why the light falls in exactly opposite directions on the opposite wings.

I heard of a curious monstrosity yesterday, seen by my mothers servant, a baby, half bear & half child, its mother had been to the Zoo. about 6 months ago & could not be got away from the bear’s den, she was suddenly brought to bed the other day by the news of her husband’s death (a false report) & as the child was completely a bear to the middle with long crooked claws to its fore-feet, the doctor ‘did not think it advisable to encourage its growth’ as the Lancet generally puts it.3

yours very sincerely | A G Butler

Xcuse a scrawl written in the dark.

CD annotations

2.1 Brahmæa Certhia] scored red crayon; underl red crayon
3.1 I heard … it. 3.6] crossed pencil
Top of letter: ‘Brahmæa Certhia’ pencil


Butler refers to specimens at the British Museum, and to his paper in Proceedings of the Zoological Society of London for 1866 (Butler 1866). See also letter from A. G. Butler, 29 June 1871 and n. 2. Butler here misspells ‘swanzii’.
Butler’s mother was Jane Isabella Butler. Her servant and the other persons mentioned have not been identified.


Butler, Arthur Gardiner. 1866. Note on the genus Brahmæa of Walker. [Read 27 February 1866.] Proceedings of the Zoological Society of London (1866): 118–21.


Observations on ocelli of Brahmaea certhia.

Monstrosity born to a woman – half bear, half human.

Letter details

Letter no.
Arthur Gardiner Butler
Charles Robert Darwin
Sent from
Source of text
DAR 89: 94–5
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 7873,” accessed on 29 November 2021,

Also published in The Correspondence of Charles Darwin, vol. 19