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Letter 7082

Bates, H. W. to Darwin, C. R.

17 Jan 1870


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.


15 Whitehall Place

Jan 17 1870

My dear Mr Darwin

I have sent to the post stamped & registered, your packet ofManuscript, which I hope will reach you safely. You will see mysuggested alterations all marked lightly in pencil in their places& will notice that they nearly all relate to the orthographyof scientific names of Insects—a very small Matter!f1

As to the facts there is only one which I do not clearlyunderstand: it is the rudiments of horns in ♀ of Onitisfurcifer. I conclude, however, that you consider the indented orflattened (retuse) front part of thorax as the rudiment of horn formation.Well, it is so in effeminate males of Phanæus onthophagus & soforth & I presume you are correct in so expressing the fact withregard to O. furcifer; but still some qualification in terms seemsnecessary.f2

Other facts I have noted are additions to your stores. Of courseI would not think of giving you new facts of those classes in whichyou have a superabundance already. But in one case—sexual dissimilarityof colours in Coleoptera,—you have clearly not enough. I haverecently been working at Longicorns, a group in which an enormousamount of modification for mere ornament has taken place & I findthat there are here many cases of sexual disparity of colours. The genera Mallaspis Pyrodes & Esmeralda, very large & beautifulPrionidæ Longicorns offer the most striking examples. In Esmeraldathe two sexes have been placed in different genera partly on accountof difference of colour. Many other genera in the tribe offerless striking cases.f3

The reasoning I had not ought to touch & have not touched in theM.S.— I almost always agree with you & have less scruple on thisaccount to suggest a modification of your view of females not beingmade dull-coloured by selection, which will bring your opinion &Wallace’s nearly into harmony.f4 It is this—the necessity of femalesbeing dull-coloured for protection is true, but they have not beenmade dull from former brighter hues, but have simply been keptdull by natural selection steadily eliminating all tendency tobrightness. This will not disagree with your clenching & true argumentagainst Wallace that females of a genus are truer in colour to thegeneric type than males.f5

Yours sincerely | H W Bates

DAR 82: A44–5



CD had evidently sent his chapters on the secondary sexualcharacters of insects for Descent (Descent 1: 341–423) to Batesfor comment.
In Descent 1: 372–3, CD argued that the thoracic crest of thefemale Onitis furcifer was indeed the rudiment of the projectionproper to the male. Onitis furcifer is now Chironitis furcifer.
CD added Bates’s information about sexual difference in colours inPrionidae to Descent 1: 367–8. Many species formerlyclassified as Mallaspis now are placed in other genera within thetribe Mallaspini (family Cerambycidae, the longhorn or longicornbeetles), to which all the genera mentioned belong. The family Prionidae is now thesubfamily Prioninae (family Cerambycidae).
CD and Alfred Russel Wallace had discussed since 1867 the relativeinfluence of protection and sexual selection in determining colourdifferences between the sexes of various organisms (seeCorrespondence vol. 15, letter from A. R. Wallace, 24 February[1867]).
See Descent 1: 404.
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