302 THE SKELETON OF THE RABBIT. 



of ribs have both capitular and tubercular articu- 

 lations with the vertebrae : in the remaining three 

 (or four) pairs, which are more slender than the 

 anterior ones, the tubercles are absent, and the 

 capitular articulations, which alone are present, 

 are confined to the corresponding vertebrae. 



The sternal portions of the first seven pairs 

 articulate directly with the sternum : the remain- 

 ing ones do not reach the sternum, though those 

 of the eighth and ninth pairs are closely con- 

 nected with the ribs in front of them. 



2. The sternum is an elongated laterally compressed 

 median rod, situated in the ventral wall of the 

 thorax, and divided transversely into 'segments or 

 sternebrae. It is developed in connection with the 

 ventral ends of the ribs, and consists at first of right 

 and left halves. 



The anterior segment or manubrium is much the 

 largest, and is produced ventral! y and in front into 

 a prominent keel. 



Behind the manubrium come four segments of 

 about equal length, then a very short segment, and 

 finally the xiphisternum, a long slender bony rod 

 ending behind in a horizontal plate of cartilage. 



The first pair of ribs articulate with the sides of 

 the manubrium, and the succeeding six pairs be- 

 tween the several sternebrse. 



C. The Skull. 



This is made up of cranium proper, olfactory and auditory 

 capsules, and visceral skeleton. The following description 

 applies not only to the skull of the rabbit but (with certain 

 modifications) to that of the dog, which is the better of the 

 two from its larger size. The differences may be understood 

 by reference to the figures and descriptions. 



In the adult rabbit, the original cartilaginous skull is 

 almost completely replaced by bones. In addition to these 



