THE SKELETON OF THE DOG. THE RIBS. 



403 



end is rounded, forming the head or capitlllum, which 

 articulates with a concave surface furnished partly by the cor- 

 responding vertebra and partly by the vertebra next in front. 

 The last three or four however articulate with one vertebra 

 only. A short way behind the capitulum on the dorsal side of 

 the rib is a rounded outgrowth, the tubercle or tuberculum, 

 by means of which the rib articulates with the transverse 

 process. The portion of the rib between the head and the 

 tubercle is known as the neck. The sternal portion of the 

 rib (fig. 76) is a short bar of calcined or imperfectly ossified 

 cartilage, about one-third of the length of the corresponding 

 bony portion. The anterior sternal ribs are somewhat more 

 cartilaginous than the posterior ones. The vertebral portions 



FIG. 76. STERNUM AND STERNAL RIBS OF A DOG (Canis familiaris) 



1. presternum. 4. 



2. first sternebra of mesoster- 



num. 



3. last sternebra of mesoster- 



num. o. 



xiphisternum. The flattened 

 cartilaginous plate termi- 

 nating the xiphisternum is 

 not shown. 



first sternal rib. 



262 



