THE SKELETON 



45 



In the anterior part of the thorax the vertebral extremity of 

 each rib is divided into two parts, " head " or " capitnlum," and 

 "tubercle"; the former is attached to the side of the body of the 

 vertebra, the latter to its 

 transverse process ; the 

 former attachment corre- 

 sponds to the interspace 

 between the vertebra?, the 

 head of the rib commonly 

 articulating partly with 

 the hinder edge of the 

 body of the vertebra ante- 

 cedent to that which bears 

 its tubercle. Hence the 

 body of the last cervical 

 vertebra usually supports 

 part of the head of the first 

 rib. In the posterior part 

 of the series the capitular 

 and tubercular attach- 

 ments commonly coalesce, 

 and the rib is attached 

 solely to its corresponding 

 vertebra. The number of pairs of ribs is of course the same as that 

 of the thoracic vertebrae. 



The circumstance that in some of the Anomodont reptiles and 



Fig. 14.— Sternum and strongly ossified sternal ribs 

 of Great Armadillo (Priodon gigas). j>s, Presternum; 

 xs, xiphisternum. 



Fig. 15. — Skeleton of Lion (Felis ho), cd, Caudal vertebrae ; cp, carpus ; cr, coraeoid process 

 of scapula ; cv, cervical vertebrae ; d, dorsal vertebra; ; fb, fibula ; fm, femur ; h, humerus ; il, 

 ilium ; isch, ischium ; I, lumbar vertebras ; m, metatarsus ; mc, metacarpus ; p, patella ; pb, pubis ; 

 ph, phalanges ; pv, pelvis ; r, radius ; s, sacral vertebrae ; sc, scapula ; sk, skull ; tb, tibia ; ts, 

 tarsus ; v., ulna ; zy, zygomatic arch. 



Labyrinthodonts the capitula of the ribs articulate with the inter- 

 central elements of the vertebral column has suggested, as in the 



