skip to content

Darwin Correspondence Project

To W. H. Edwards   23 April [1872]1

Down, | Beckenham, Kent.

April. 23d

Dear Sir

I am very much obliged to you for your kindness in having sent me Part 9. of your Butterflies, which is one of the most beautiful works which I have seen.2 Your careful observations on the dimorphism or rather trimorphism of Papilio ajax, strike me as most remarkable & interesting.3

Believe me Dear Sir | Yours very faithfully | Charles Darwin


The year is established by the reference to Edwards’s work (see n. 2, below).
Edwards sent part 9 of The butterflies of North America (Edwards 1868–72), which was published in December 1871. CD’s annotated copy is in the Darwin Pamphlet Collection–CUL.
In the section of Edwards 1868–72 (unpaginated) titled ‘Papilio III’, Edwards discussed his experimental breeding of different varieties of Papilio ajax (now Iphiclides ajax, the zebra swallowtail). He concluded that the three forms were seasonal variations of one species.


Thanks for part nine of WHE’s [Butterflies of North America (1868–72)].

Comments on trimorphism in Papilio ajax.

Please cite as

Darwin Correspondence Project, “Letter no. 8299,” accessed on 24 June 2018,

Also published in The Correspondence of Charles Darwin, vol. 20