[30]

(30

[later insertion by Darwin:] Ch. Darwin─ Descent of man.─

Ch. I

its correlated accessory muscles & other structures, is formed especially well developed in birds, in which it & is of high functional importance, as it can be rapidly drawn across the whole eye-ball.

It is found in some reptiles & amphibians, & cru in certain fishes, as in sharks. It is fairly well developed in some few of the higher mammals as in the walrus & in a less degree in the elephant the two lower divisions of the mammalian series, namely the monotremata & marsupials, & in some few of the higher mammals, as in the walrus. But in man, all the g monkey Quadrumana, & some other mammals, it is exists can admitted by all anatomists to exist as a mere useless rudiment under the name of the semilunar fold. *26)

(The sense of smell is of the highest importance to most the greater number of mammals—to some, as the ruminants, in warning them of danger; to others, as the carnivora, in finding their prey, to others, as the wild-boar, for both purposes combined. But the sense of smell is of extremely slight