312 THE SKELETON OF THE BABBIT. 



u. The anterior incisors are long, and curved 

 almost into semicircles, the greater part of 

 each being lodged in an alveolus which 

 extends almost to the hinder end of the 

 bone. Along the anterior surface the 

 enamel is thick, and folded so as to form 

 a longitudinal groove. Behind and at the 

 side it is much thinner, and hence wears 

 away sooner, rendering the cutting edge 

 chisel-shaped. 

 /3. The posterior incisors, which are lodged in 

 alveoli immediately behind the anterior 

 ones, are much smaller and slightly curved. 



ii. The grinding teeth form a set of six teeth on 



each side, borne by the maxilla, and divisible 



into two groups. 



a. The premolars are the three anterior grinders 



of each side, and are distinguished from 



the posterior ones by the fact that, like the 



incisors, they are preceded in early life by 



' milk ' or deciduous teeth, which in the 



rabbit are shed shortly after birth. 



Each premolar is flattened from before 

 backwards, and each of the two hinder ones 

 has a deep groove along its outer surface 

 which carries the enamel almost across the 

 tooth, giving rise to a prominent ridge on 

 the grinding surface. 



/3. The molars are the three posterior grinders 

 on each side ; they differ from the premolars 

 in having no deciduous predecessors. The 

 first two are similar to the premolars ; the 

 last is small and not grooved. 



b. The teeth of the lower jaw. 



i. The incisors are two in number, and project for- 

 wards from the anterior end of the mandible. 



