THE ASCENT OF MAN. 453 



icnkv, a muscle present in most mammals and used to |»ull forwiud the 

 shoulder girdle when walking" in a (juadrupetla! position. In negroes 1 

 have frequently fouiul it more or less complete. A librons strip unit- 

 ing- the latissimus dotsi to the triceps is all that remains of an imi)or- 

 tant muscle, the <lorsocpi,troehlearis, passing from the back to the elbow 

 or forearm, used by gibbons and other arboreal apes in swinging from 

 branch to branch. Testut found this fully develoj)ed in a Bushman. I 

 have myself seen various muscular slips that must re[)resent some por- 

 tions of it, and authors generally describe it as occurring in 5 or O per 

 cent, of individuals. 



The hind limbs of apes are popularly thought to be remarkably 

 specialized. The term quadrumana or four-handed is used to charac- 

 terize the class ; yet it is quite true that this term involves a false con- 

 ception. No animal has four exactly similar feet, still less four hands. 

 The feet of the ape differ widely from hands ; the great toe is not really 

 opposable like the thumb, but merely separable from the others and 

 differently set, so as to afford a grasp like that of a cramp iron. The 

 gibbon alone has a small muscle of the foot that may be compared with 

 the opponens of the thumb. That these peculiarities are also shared 

 by man to some extent is well known. It is quite possible to train 

 the toes to do certain kind of prehensile work, even to write, cut paper, 

 and sew. A baby not yet able to walk can often pick u}) small objects 

 with its toes. Compare the marks caused by muscular action on the 

 sole of a baby's foot with those on the hand, and it will be seen that 

 there are distinct; signs of this prehension. Even the opponens hallucis 

 of the gibbon is not infrequently found in man. The fo?tal condition 

 of the foot also approaches that of the apes, the heel being shorter and 

 the joints so arranged that the sole can be easily turned inward. In 

 the ape the first or great toe is turned inward and upward by shorten- 

 ing its metatarsal bone and setting it obliquely upon the ankle. This 

 shortening and obliquity also occurs in the fuitus; the adult condition, 

 in which the metatarsal bone is lengthened and set straight so as to 

 give a longer and firmer internal border to the foot, being gradually 

 acquired. Many savage tribes still use the foot for climbing and have 

 a shorter metatarsal, a wider span between the first and second toes, 

 and greater ease in inverting the sole. Connected with this ease of 

 inv^ersion should be mentioned a i)eculiar, ape-like form of the tibia that 

 occurs in people of the stone age, in the mound builders, and in some 

 American Indians. This is a flattened, saber-like condition of the bone 

 known as platycnemy. It is apparently to give greater surface of 

 attachment and resistance to the pull of the tibialis anticus, the prin- 

 cipal muscle that turns the sole inward. It is interesting to note that 

 this peculiarity is much more marked in some early hnman skeletons 

 than in any of the anthropoid apes. 



The poet says that while other animals grovelling regar<l the earth, 



