148 ANIMAL BIOLOGY. [Part I. 



the hinder part of this bar is a separate bone, the malar or jugal. 

 [The incomplete partition in the dog or cat is formed by an 

 ascending process of the malar, which nearly meets a descending 

 process of the frontal.] 



(5.) The Maxillary Region. The tooth-bearing bones in the 

 upper jaw are the maxillae (mx.) and pre-maxillae (p.mx.). The 

 maxillae are large and irregular. Their palatal processes have 

 already been considered. Each bears three pre-molar and three 

 molar teeth in the adult. The pre-maxillse are long, and articu- 

 late with each other closely, though they do not ankylose. 

 Each has three large processes : (1) a nasal process (n. p.} pass- 

 ing along the outer edge of the nasal bones ; (2) a maxillary 

 process (m. p.) coming into relation with the maxilla; and (3) 

 a palatine process (Fig. 46, pa. p. pr.) passing backwards along- 

 side its fellow, and partially dividing from each other the 

 anterior palatine foramina (a. p. /.). Each bears two incisor 

 teeth, one behind the other; the anterior large, the posterior 

 small. A long space, or diastema, separates the incisors from 

 the pre-molars. There are no canine teeth. 



(6.) The Mandible. The lower jaw is composed of two sym- 

 metrical rami which meet, but do not ankylose, at the symphysis. 

 It articulates directly with the skull by a longitudinally elongated 

 condyle, which fits in beneath the zygomatic process of the 

 squamosal. Running up towards the condyle, from the tooth- 

 bearing or horizontal portion, is an ascending portion which 

 bears an incurved coronoid process. At the junction of the 

 two portions is an inferior dental foramen for a branch of the 

 fifth nerve. The angle is rounded, and has a slight shelf pro- 

 jecting inwards. 



The lower jaw in the adult bears two incisor teeth, one in 

 each ramus ; no canines ; two pre-molars and three molars on 

 each side. The following dental formula will now be under- 

 stood. The numbers above and below the line represent the 

 teeth in the upper and lower jaw respectively those of the 

 opposite sides being separated by the : 



_ ,, ., . 2-2 0-0 3-3 3-3 OQ 



Rabbit, i. I 1 , c. ra , p. m. , m. 3 ^, =28. 



