354 



MAMMALIAN ANATOMY 



Fro. 273. 



FRONT VIEW. 



Its upper outer part is continuous with the outer surface of the nasal 

 process. Its internal border is straight and vertical, and unites with 



the corresponding border of the 

 opposite bone. The external 

 border is also straight, vertical, 

 but slightly serrated, and is the 

 anterior border of the external 

 surface, for articulation with the 

 maxillary. The inferior border 

 shows on its inner half three 

 small emarginations, which are 

 the sides of the openings for the 

 incisors on the lower surface, 

 and on its outer half a long 

 faint eniargination marking the 

 diastema between the incisors 

 and the canine. The superior 

 border is hardly distinct, inas- 

 much as the inner half of the 

 anterior surface curves up on 

 the superior surface. At the 

 middle is a tubercle from which 

 springs the anterior border of 

 the nasal process. 



The external surface (Fig. 

 275) faces outward and back- 

 ward ; it is triangular, the apex 

 pointing upward, and continuous 

 with the posterior border of the 

 nasal process. The anterior 

 border is convex, the posterior 

 concave; the base is straight and 

 slants upward and backward. 



The external surface is excavated and rough, and joins the maxillary. 

 The internal surface (Fig. 278) is flat and continuous with the 

 internal surface of the palatine process. It is quadrate, and longer 

 than high, with the upper anterior angle rounded and the posterior 

 lower border emarginate posteriorly. 



LOWER VIEW. 

 POSITION OF LEFT PREMAXILLARY BONE. 



