PLATE 4 



EXPLANATION OF FIGURES 



7 Sternum and ends of costal cartilages in pig two weeks old. Note in 

 this and later figures that centers of ossification are intercostal. 



8 Fetal sternum of Bradypus. After Hoffmann. 



9 The ape sternum. After Anthony. 



10 Sternum of Dasypus. After Hoffman. From the lowest to the highest 

 mammals the sternebrae and centers of ossification are between the ribs, and 

 not at their ends as would be expected according to Paige's theory. 



Oc, ossific center 



98 



