304 THE EVOLUTION OF MAN. 



and a lower (ventral) piece ; the anterior portion of the 

 latter constitutes the pro-key (or collar) bone (procoracoi- 

 dcum) and its posterior part the raven-bone (coracoideum). 

 Tlie simple arch of the pelvic girdle breaks up, correspond- 

 ingly, into an upper (dorsal) piece — the intestinal bone 

 {os iliurn), and a lower (ventral) piece; the anterior portion 

 of the latter becomes the pubic bone (os pubis) and the 

 posterior portion the hip-bone (os ischii). Table XXXIV., 

 p. 278, shows the correspondence of these three parts of 

 the pelvic girdle with those of the shoulder-girdle. The 

 latter, however, in the key-bone or collar-bone (clavicula), 

 possesses a fourth, wanting in the former. (Cf Gegenbaur.^^^) 

 As in the girdle, so in the trunk of the limbs there is 

 originally an absolute agreement between the anterior and 

 posterior limbs. The first section of the trunk is supported 

 by a single strong bone — in the anterior limbs, the upper 

 arm {humerus) ; in the posterior, the upper leg {femur). 

 The second section, on the other hand, contains two bones — 

 on the anterior extremity the spoke-bone {radius. Fig. 

 •270, r), and the ell-bone {ulna, Fig. 270, u) ; in the posterior 

 the two corresponding bones, the shin-bone {tibia) and 

 calf-bone {fibula). (Cf skeletons in Fig. 19G and Figs. 

 204-208). -Moreover, the subsequent small and numerous 

 bones of the wrist {carpus) and of the ankle {tarsus) cor- 

 respond ; so do the five bones of the middle of the hand 

 {metacarpus) and of the middle of the foot {metatarsus). 

 Finally, the same is true of the five digits attached to these 

 parts, which in their characteristic structure of a series of 

 bone-pieces correspond in the anterior and posterior limbs. 

 Charles Martins, of Montpellier, an excellent morphologist 

 has shown that, in detail, the anterior and posterior limbs 

 correspond. ^^^ 



