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Darwin Correspondence Project

From Edward Blyth   26 April 1869

21 Chalcot Crescent, | Regent’s Pk,

April 26/69.

Dear Mr. Darwin,

I was unable last week to visit the B.M., but I examined the rhesus monkeys at the Gardens, & there is no difference whatever in the amount of extension of the nude face in the two sexes.1 In the females of this group, the sexual organs exhibit an immense development at times, as you cannot but know. In the mandrill & drill, which animals exemplify the culmination of the Macacus & Cercopithecus series, the full grown females are very much smaller than the full-grown males; & in the male mandrill more especially the peculiar characteristics of the series are most highly enhanced; the brilliant colouring of the nude & especially of the sexual organs, most unusual in the class mammalia, but which is also seen in some of the small Cercopitheci.2

That is a capital figure of the musk-deer in last weeks no. of the Illustrated London News, & I furnished the description of it. I have now just written to the editor of that paper, to request him to figure the Abyssinian wart-hog (Phacochœrus Æliani) that has recently arrived, and which is much more different from the Southern species (P. æthiopicus) than I had expected.3 Although a half-grown sow, I can perceive that the curious facial appendages will be much less developed than in the female of the Southern species, and it has immense white whiskers, & very long flowing black hair upon the middle of its back—

Yours very truly, | E Blyth

CD annotations

1.1 I was . . . examined] crossed blue crayon
1.1 the rhesus … sexes. 1.3] enclosed in square bracket blue crayon
1.3 In … back— 2.8] crossed blue crayon
Top of letter: ‘(Naked skin & Colour)’ blue crayon; square brackets in MS; ‘Add that no difference in Hairiness in the 2 sexes.—’ ink


The mandrill (probably Mandrillus sphinx is referred to) and drill (Mandrillus leucophaeus) are members of the family Cercopithecidae. The genera Macaca (formerly Macacus) and Cercopithecus are also part of the same family.
A picture of musk-deer recently arrived at the gardens of the Zoological Society of London was published in the Illustrated London News for 24 April 1869, p. 408; Blyth’s description was on p. 422. The editor of the Illustrated London News was John Lash Latey. No picture of a warthog appeared in May 1869. An Abyssinian warthog was purchased by the Zoological Society and arrived on 15 April 1869 (Proceedings of the Zoological Society of London (1869): 665). Phacochoerus aethiopicus is the desert warthog; P. aeliani is now P. africanus aeliani, the Eritrean warthog.


Has found no difference between male and female rhesus monkeys at the Zoological Gardens in amount of facial hairiness. Observations on other monkeys.

Letter details

Letter no.
Edward Blyth
Charles Robert Darwin
Sent from
London, Chalcot Crescent, 20
Source of text
DAR 85: A107–8
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6713,” accessed on 3 August 2020,

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