Dear Sir,

I beg to call your attention to an instance of correlation in colour which I have, for some months past, observed as invariable. It is that a cat with a white throat, or with a white spot on the throat, has always four white feet.¹

Black & white, or coloured & white cattle have usually from what I have observed of late, white tails.

I noticed last year when I was in Auvergne that the extremities of the tails of the black & white sheep were invariably white.

That dogs which have any white about their bodies usually have white-tipped tails has been remarked by yourself—² the exceptions are I think most frequent in curly-haired dogs.

I trust that you will not give yourself the trouble to reply to this letter, & I beg to remain, with the profoundest respect, | Yours faithfully | H. W. Jackson

Charles Darwin, Esq^re | F.R.S. &c &c.