THE TEETH 293 



p. 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. 



1). The teeth of the lower jaw. 



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

 wards from the anterior end of the mandible. 

 They are similar to the large upper incisors, but 

 are less strongly curved and are not grooved : 

 the alveoli in which they are lodged extend 

 back in the jaw as far as the anterior grinders. 



ii. The grinding teeth form a set of five on each 

 side, placed opposite to those of the upper 

 jaw, and'like these divisible into two groups. 

 They difier 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. 



/3. 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 APPENDICULAB SKELETON. 



The appendicular skeleton comprises the bones of the two 

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



