Neural arck 



k t/^^X 



Neural arc 



Centrum — • ) 



True rib^^ 



A. Dogfish 



Fish rib 



B. Crossopterygian 



C. Amphibian 



Fig. 89. Structure of Ribs. Evohition of the true (myoseptal) ribs; and 

 the position of the ''fish" ribs of the Crossopterygii and Teleostei. 



Sternum 



Fig. 90. Thorax of Man. The 



relationship between the ribs, the 



vertebrae and the sternum is 



shown. 



Centrum 



Sternum 



Fig. 91. Cross Section of the 



Thorax of Man. Compare with 



Figures 89 and 90. 



