LEPUS CUNICULUS 



277 



Ribs and Sternum. 



The ribs in the rabbit number twelve or sometimes thirteen 

 pairs, and together with the backbone and the sternum constitute 

 a bony basket in which lies the thorax. Each rib is a curved, some- 

 what flattened rod of bone passing out laterally and slightly back- 

 wards from the vertebral column. The dorsal end is enlarged to 



M 



5r 



FIG. 89 Rib of Lepus viewed 

 from anterior aspect. 



C., capitulum ; S., sternal portion ; 

 T., tuberculum ; V., vertebral por- 

 tion. 



FIG. 90. Sternum of Lepus from 

 ventral surface. 



M., manubrium ; S., sternal portions of 

 ribs ; St., sternebrap ; V., vertebral por- 

 tions of ribs ; X., xiphisternum. 



form a knob-like head or capitulum which articulates with the 

 facets on the centra. Just lateral to this is given off a dorsal pro- 

 jection, the tuberculum, which, as we have seen, articulates with 

 a facet on the under side of the transverse process of a thoracic 

 vertebra ; but such a tubercle is absent on the posterior three or 

 four pairs which have only a capitulum. To the lateral extremity 

 of each bony vertebral part of the rib is attached a short bar of 

 calcified or incompletely ossified cartilage, the sternal portion, 



