Dear Sir

I am afraid you will be quite sick of me & my butterflies, but, whilst sketching the moth (of which part is given below) for one of my plates I was struck with the strong analogy between the marginal ocelli & those on the Argus-pheasant & I thought you might be interested by a sight of it;¹

the gradations between the perfect & imperfect ocelli seem to point to the manner in which the former have been developed from the latter; all the species of Brahmæa are similarly ocellated, but B. Swanzyi & perhaps B. lucinæ* are the only species which exhibit an approach to the ball & socket ocellation.²

I think I may be wrong in my supposition respecting the identity of Elymnias Kamara & E. Ceryx, I find that M^r. Wallace has described a ♂ E. Ceryx which he says only differs from the ♀ in its darker colouring; still the ♀ of E. Kamara ought, judging by analogy, to be not unlike it.³

There is a curious example in the B. M. Coll. of ‘Natura facit saltum’⁴ a black form of Junonia Sophia Fabr. which looks exactly like a very small example of Panopea Lucretia Cramer; the ordinary colouring of J. Sophia is tawny, with brown or blackish bars across the wings; both species occur at Sierra Leone, yet it cannot be a case of mimicry since the black form is abnormal & the Panopea is itself a bad mimic of an Acrœa; I think however that such a variety, if necessary to the preservation of the species (i.e if J. Sophia were persecuted & P. Lucretia a protected form) might be retained & a mimic comparatively suddenly created.⁵

Many of M^r. Higgins’ ideas about the formation of markings on butterflies were based upon the notion that the wings of a butterfly were folded within the pupa, this is of course an error, the wing is of the same shape within the pupa as in the imago.⁶

I see that you often speak, in ‘Sexual Selection’, of the pugnacity of the ♂ Stickle-back during the breeding season⁷   I used to be much annoyed by it when a boy, for I always went to the Wandsworth-ponds with the intention of only bringing home the pretty Stickle-backs & I generally threw away most of the females; in two or three days all, or all but one of my fish were dead, many of them being struck in the eye by the spines of their companions.

Believe me to be | yours very sincerely | A G Butler.

*Brahmæa lucina is a species known only from Drury’s figure   See P. Z. S. 1866. p. 121.⁸

Ch. Darwin Esq^re. FRS &c