My dear Sir

I am obliged for your interesting fact.¹ I have heard of analogous cases, especially of a striking one in Ceylon.² Like you I have often wondered at the different food of the old and young, as with graminivorous birds feeding their young with insects. I imagine we must look back to primeval times when the young and old lived on the same food. Sir J. Lubbock in his forthcoming Vol. in the Ray Soc. will give some valuable remarks on the means of transition between the mandibulata and haustellata.³ I think the Gonepteryx must feed on some plants besides the Rhamnus, for I believe this bush in many districts is absent, whilst the butterfly is common.⁴

With many thanks for your note believe me | Yours very sincerely | Ch. Darwin.