304 THE EVOLUTION OF MAN. 



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

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

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

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

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

 (os ilium), 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. 182 ) 

 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. 196 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. 183 



