THE TEETH 285 



side, placed opposite to those of the upper 

 jaw, and like these divisible into two groups. 

 They differ from the upper grinders in being 

 curved so as to be convex instead of concave 

 outwards. 



a. The premolars are the two anterior grinders 

 on each side. They are somewhat similar 

 to the upper ones, but narrower from side 

 to side. The outer surface of the first, which 

 is the larger of the two, is marked by two 

 deep longitudinal grooves, and that of the 

 second by a single groove. The inner sur- 

 face of each is less deeply grooved than the 

 outer. 



ft. The molars are the three hinder grinders on 

 each side ; they are similar to the second 

 premolars, but have no deciduous pre- 

 decessors : the posterior one is smaller and 

 simpler than the other two. 



II. THE APPENDICULAE SKELETON. 



The appendicular skeleton comprises the bones of the two 

 pairs of limbs, and the girdles which support them. The 

 bones of the limbs are mostly elongated, and provided with 

 epiphyses at their ends. 



A. The Pectoral Girdle. 



This lies outside the ribs, and is attached to the axial 

 skeleton by muscles and ligaments only. In the rabbit, as 

 in nearly all other mammals, it is very incomplete : the dorsal 

 or scapular portion on each side is well developed, but the 

 ventral or coracoid portion is almost entirely absent, being 

 represented merely by a small knob of bone fused with the 

 scapula : the clavicles also are imperfect. 



i. The scapula is a triangular plate of bone, the 

 apex of which is directed downwards and for- 

 wards, and is expanded and hollowed on its 



