EVIDENCE FROM TAILS, LIMBS, 6- LUKGS^ Of AJJIMALS,. 101 



region amongst other parts and details of structure. It is not more 

 surprising, in truth, to find that man in early life possesses an undeni- 

 able tail (Fig. 37, D) than to discover that he is provided at the same 

 period with a series of clefts and arches in the side of his neck 

 (Fig. 37, g) corresponding to the gill-clefts and gill-arches of fishes and 

 other gill-possessing vertebrates. Like his gill-clefts, man's caudal 

 appendage gradually becomes abortive as development proceeds ; 

 but he retains the rudiment of his tail, whilst the gill-clefts entirely 

 disappear. Nor is this all. When the coccyx of man (Fig. 36) is 

 examined in its ordinary and adult condition, it is found to be 

 provided with the merest rudiments of muscles, one of which cor- 

 responds to a very large extensor muscle developed in the tail of 

 many quadrupeds just, indeed, as man possesses a representative 

 rudiment of the muscle by which the dog and horse shake their 

 coats, as well as thoroughly useless rudiments of the muscles which 

 move the ears of his lower neighbours. Thus man's coccyx furnishes 

 important evidence of his origin, and the isolated facts of human 

 anatomy regarding the tip of the human spine fall naturally into the 

 service of the theory of development which relates man in the most 

 intimate fashion to lower but no less wondrously formed creatures. 



With the opinions of that learned Scottish judge, Lord Mon- 

 boddo, respecting the causes of disappearance of the human tail, 

 most readers are well acquainted. In his day Lord Monboddo was 

 esteemed the shrewdest of men ; and, despite the fact that his theory 

 of the disappearance of man's tail through the friction of pressure 

 produced by the sitting posture has been a stock subject with those 

 who can afford to treat such subjects in a flippant manner, one may 

 be excused for suspecting that his lordship certainly meant what 

 he wrote. It is extremely interesting, therefore, to find that Mr. 

 Darwin, strengthening himself by observation on the manner in 

 which certain apes dispose of their rudimentary tails, comes to the 

 conclusion that the theory of the tail's disappearance through friction 

 " is not so ridiculous as it at first appears." A certain monkey, a 

 species of Macaque, possesses a short tail composed of eleven joints, 

 whilst its tip is very flexible and sinewy. In the sitting posture this 

 tail may prove a decided inconvenience to the animal. It is fre- 

 quently bent under the body, and a peculiar curve exhibited by the 

 tail leads to the belief that the tail had originally been bent round 

 by the will of the animal, and so disposed as to prevent being pressed 

 into the ground. One result of this adaptation to the sitting posture 

 is that the tail is rough and hard ; and as we know from positive 

 evidence that the mutilations and injuries of the parent may be in- 

 herited by the offspring, it is conceivable that the short tails of many 

 monkeys indicate the results of degeneration from the effects of 

 gradual and inherited mutilation. This idea is strengthened in a 



