Dear M^r. Darwin,

I was unable last week to visit the B.M., but I examined the rhesus monkeys at the Gardens, & there is no difference whatever in the amount of extension of the nude face in the two sexes.¹ In the females of this group, the sexual organs exhibit an immense development at times, as you cannot but know. In the mandrill & drill, which animals exemplify the culmination of the Macacus & Cercopithecus series, the full grown females are very much smaller than the full-grown males; & in the male mandrill more especially the peculiar characteristics of the series are most highly enhanced; the brilliant colouring of the nude & especially of the sexual organs, most unusual in the class mammalia, but which is also seen in some of the small Cercopitheci.²

That is a capital figure of the musk-deer in last weeks no. of the Illustrated London News, & I furnished the description of it. I have now just written to the editor of that paper, to request him to figure the Abyssinian wart-hog (Phacochœrus Æliani) that has recently arrived, and which is much more different from the Southern species (P. æthiopicus) than I had expected.³ Although a half-grown sow, I can perceive that the curious facial appendages will be much less developed than in the female of the Southern species, and it has immense white whiskers, & very long flowing black hair upon the middle of its back—

Yours very truly, | E Blyth