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Darwin Correspondence Project

From Henry Walter Bates   17 January 1870

15 Whitehall Place

Jan 17 1870

My dear Mr Darwin

I have sent to the post stamped & registered, your packet of Manuscript, which I hope will reach you safely. You will see my suggested alterations all marked lightly in pencil in their places & will notice that they nearly all relate to the orthography of scientific names of Insects—a very small Matter!1

As to the facts there is only one which I do not clearly understand: it is the rudiments of horns in ♀ of Onitis furcifer. I conclude, however, that you consider the indented or flattened (retuse) front part of thorax as the rudiment of horn formation. Well, it is so in effeminate males of Phanæus onthophagus & so forth & I presume you are correct in so expressing the fact with regard to O. furcifer; but still some qualification in terms seems necessary.2

Other facts I have noted are additions to your stores. Of course I would not think of giving you new facts of those classes in which you have a superabundance already. But in one case—sexual dissimilarity of colours in Coleoptera,—you have clearly not enough. I have recently been working at Longicorns, a group in which an enormous amount of modification for mere ornament has taken place & I find that there are here many cases of sexual disparity of colours. The genera Mallaspis Pyrodes & Esmeralda, very large & beautiful Prionidæ Longicorns offer the most striking examples. In Esmeralda the two sexes have been placed in different genera partly on account of difference of colour. Many other genera in the tribe offer less striking cases.3

The reasoning I had not ought to touch & have not touched in the M.S.— I almost always agree with you & have less scruple on this account to suggest a modification of your view of females not being made dull-coloured by selection, which will bring your opinion & Wallace’s nearly into harmony.4 It is this—the necessity of females being dull-coloured for protection is true, but they have not been made dull from former brighter hues, but have simply been kept dull by natural selection steadily eliminating all tendency to brightness. This will not disagree with your clenching & true argument against Wallace that females of a genus are truer in colour to the generic type than males.5

Yours sincerely | H W Bates

CD annotations

1.1 I have … Matter! 1.4] crossed pencil
2.2 I conclude, … necessary. 2.6] crossed pencil
3.6 The genera … beautiful 3.7] scored pencil
3.7 Prionidæ … of colour. 3.9] double scored pencil
4.1 The reasoning … males. 4.9] crossed pencil
Top of letter: ‘40 Bartholomew Rd, Kentish Town—’ pencil


CD had evidently sent his chapters on the secondary sexual characters of insects for Descent (Descent 1: 341–423) to Bates for comment.
In Descent 1: 372–3, CD argued that the thoracic crest of the female Onitis furcifer was indeed the rudiment of the projection proper to the male. Onitis furcifer is now Chironitis furcifer.
CD added Bates’s information about sexual difference in colours in Prionidae to Descent 1: 367–8. Many species formerly classified as Mallaspis now are placed in other genera within the tribe Mallaspini (family Cerambycidae, the longhorn or longicorn beetles), to which all the genera mentioned belong. The family Prionidae is now the subfamily Prioninae (family Cerambycidae).
CD and Alfred Russel Wallace had discussed since 1867 the relative influence of protection and sexual selection in determining colour differences between the sexes of various organisms (see Correspondence vol. 15, letter from A. R. Wallace, 24 February [1867]).
See Descent 1: 404.


Returns CD’s MS [of entomological section of Descent] marked with suggested alterations.

Suggests qualifications about rudimentary horn in female Onitis furcifer [See Descent 1: 372].

Sends additional data on colour differences in sexes of longicorn Coleoptera [See Descent 1: 367–8].

Suggests a modification of CD’s view of female coloration that would bring him "nearly into harmony" with Wallace.

Letter details

Letter no.
Henry Walter Bates
Charles Robert Darwin
Sent from
R. Geogr. Soc.
Source of text
DAR 82: A44–5
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 7082,” accessed on 19 August 2017,

Also published in The Correspondence of Charles Darwin, vol. 18