Among the rudiments that are peculiar to man, and which are supposed to be proofs of his cognate relations to the lower animals, we are referred to certain muscles in a reduced condition, which in the other animals are used to move, twitch, or contract the skin, and remnants of which, in an efficient state, are found in various parts of our bodies; for instance, the muscles which raise the eyebrows, those which contract the scalp, those which, in some individuals, move the external ear, and similar muscular powers in different parts of the body. These are adduced as illustrations of the persistent transmission of an absolutely useless, or almost useless, faculty, "probably" derived from our remote semi-human progenitors. There is also another rudiment in man, found in the covering of the eye, and called by anatomists the "semi-lunar fold," which in birds is of great functional importance, as it can be rapidly drawn across the whole eyeball. In those animals in which, with its accessory muscles and other structures, it is well developed, as in some reptiles and amphibians, and in sharks, it is a third eyelid. In the two lower divisions of the mammalian series, the monotremata and the marsupials, and in some few of the higher mammals, as in the walrus, it is said to be fairly well developed. But in man, in the quadrumana, and most other mammals, it has become a mere rudiment. The sense of smell in man is also classed by Darwin and other naturalists among the rudiments. It is argued that it was not originally acquired by man as he now exists, but that he has inherited this power, in an enfeebled and so far rudimentary condition, from some early progenitor, to whom it was highly serviceable, and by whom it was continually used. Then we have the rudiment of hair, which, so far as it now exists on different parts of our body, is regarded as a mere remnant of the uniform hairy coat of the lower animals. Man, as he is now born, "differs conspicuously from all the other primates in being almost naked." But this nearly nude condition was not, it is said, the condition of his progenitors, and it is not the condition of his co-descendants from the same progenitors. At some time the progenitors of man and his co-descendants became covered all over with a coat of hair. What remains upon our bodies of this peculiar growth, that is called hair, is what was left after the agency of natural selection had worked off what was useless to the successive animals, and sexual selection had operated to transmit to offspring the absence of hair that had accrued in the nearer progenitors and the immediate parents. The illustrations which render this view "probable" do not need to be repeated, nor is it necessary to follow out the speculations concerning the mode in which our progenitors, near or remote, became varied in respect to the quantity, position, or direction of the hairs on various parts of their bodies.