To W. D. Fox    [29 July 1828]

Dear Fox

What excuse have you to offer for not having answered my letter long before this? I hope it is nothing worse than idleness; or what would be still better, I hope it arises from your being 10 fathoms deep in the Mathematics, & if you are God help you, for so am I, only with this difference I stick fast in the mud at the bottom & there I shall remain in statu quo.—¹

But you see I can afford time to write a single letter.— but I will not mention, how long I have been hoping in vain to receive a letter from my old master; more especially at this present time, when, if you remember; we talked of meeting on the top of some Welch mountain between Barmouth & Tenby. I will not flatter you, by saying how much I wish to hear what you yourself are doing & how entomology & your 101 other pursuits are going on? After this aweful Philippic I hope I shall soon receive a letter.—

I have been at Barmouth ever since the first of July, & like it very much; the scenery & therefore the walks are quite delightful. I only wish you would make a trip here, & I would Cicerone you up & down the mountains, untill you had not a particle of wind left in your lungs.— I go on very badly with Mathematics; neither have I succeeded so well as I expected in entomology: but I must mention a few of the most conspicuous insects or rather those which I can at all describe. Amongst the Lepidoptera, the Pterophorus Pentadactylus (Lamarck), a most extraordinary moth,—several large moths, one of which is figured in Samouelle; brown with a white band & spots; a beautiful small copper coloured butterfly, with a little tail like the Machæon: allso a sphinx Zigena (Lam:).

Inter Coleoptera—. A carabus, larger than the Violaceus, jet black & smooth.— Of the Carabidæ, one very odd one; black polished; very long; thorax, orbicular, & sep⁠⟨⁠arate⁠⟩⁠ from the abdomen, of this length caught near sea side.— A Donacia, with calves as big as mine; several large Cimices, one most beautiful, scarlet & black;— a red & black Ptinus, with a thorax like a night-cap; et multa alia.— How go on the Chrysalises If you answer this letter, tell me of your success in the science, (of names, I am afraid).—

We have heard several times from Erasmus, he has changed his plans so often; that to follow him in his course would be to pursue a Machæon on a windy day. I have nothing more to write about, but I hope soon to write again.— Heaven knows this effusion will not tempt you to write again: but I must take my chance.—

My dear old Fox I long to see you again, but I suppose it will not be before Term begins | Believe me your most sincere & loving

cousin —– n²

| Charles Darwin

(n, being an unknown quantity, this formula will exactly express our relationship)