My dear Sir,

The female of Ornithoptera magellanus is slightly shot with opaline, but not by any means to the same extent as the male, the hindwings are also heavily spotted with black as in the allied forms.¹

We have 18 species of the yellow-winged group, but O. magellanus is the only one which shows an opaline lustre; the female of this species, although not in our Collection is figured in the ‘Reise der Novara’.²

The females of Apatura laurentia, lavinia and allies have no shot-colouring, but are mimickers of the genus Heterochroa, a group of black, white and orange butterflies.³

The dash of green which you speak of in the females of Ornithoptera is rather a greenish tint in the yellow common to both sexes when seen with the tail to the light; in the same way you will remember that, when held between you and the light and looked at obliquely the same wings are of a golden orange tint.

Believe me to be | Very sincerely yours | Arthur G. Butler

D^r. Ch. Darwin F.R.S. | &c &c &c