To Joseph Wolf   3 March 1871

Dear Sir,—

You said that you would be so kind as to endeavour to make a sketch for a wood-cut of a monkey’s face when laughing, as the keepers express it. The Barbary ape would have been incomparably the best, but is dead.¹ I found, however, in the Zoological Gardens a species that does fairly well, viz. the Cynopithecus niger of Celebes, though it unfortunately has permanent transverse wrinkles on the face.² It can be easily caught, and Mr. Bartlett³ said could be put in a separate cage to be drawn. There ought to be a drawing of the face when tranquil and the mouth closed; and another of the same size and in the same position, whilst laughing. When Sutton⁴ the keeper allows this monkey to play with his hair, it chuckles or laughs, and keeps moderately still. The face then becomes a good deal wrinkled, and as far as I could see under disadvantageous circumstances, the skin is especially raised and wrinkled under the lower eyelids. When I asked Mr. Bartlett whether he thought you could possibly draw the laughter of so restless an animal, he answered that “Mr. Wolf has got an eye like photographic paper, it will seize on anything!”

I enclose the size of my page for any figures.

Also a drawing of a leopard which (excepting that the mouth is here more widely opened) shows fairly well the appearance of a cat when savage, and not at all frightened, as I have occasionally though rarely seen.⁵

I hope to get a photograph of Herring’s picture of a savage horse and another of a pleased one.⁶ Your willingness to assist me as far as lies in your power has relieved me from much difficulty.—

Dear Sir, Yours very faithfully, Ch. Darwin.