254 THE VERTEBRATE SKELETON. 



The maxillae (figs. 43, A, 2 and 44, 2) are a pair of very 

 large bones and bear the remaining teeth of the upper jaw, 

 set in sockets along their alveolar borders. On the dorsal 

 side each maxilla is continuous with the premaxilla, nasal, 

 lachrymal, and jugal, while ventrally it meets its fellow in a 

 long straight suture and forms the greater part of the long- 

 bony palate. The maxillae are separated in the middle line 

 posteriorly by processes from the palatines, while further back 

 they meet the transpalatines. The internal or nasal surface, 

 like that of the premaxilla, is excavated by a deep longitudi- 

 nal groove, the narial passage. In a ventral view of. the 

 skull a number of small openings (fig. 43, A, 21) are seen 

 close to the alveolar border, these are the openings of small 

 vascular canals which lead into the alveolar sinus, a passage 

 traversing the maxilla, and transmitting the superior max- 

 illary branch of the trigeminal nerve and certain blood-vessels. 

 This alveolar sinus opens posteriorly by the more external of 

 the two large holes in the maxilla, which lie close to the 

 anterior edge of the posterior palatine vacuity, to be described 

 immediately. The more internal of these holes, on the other 

 hand, leads into a cavity lodging the nasal sac. Behind the 

 maxillae the completeness of the palate is broken up by the 

 large oval posterior palatine vacuities (fig. 43, A, 7) ; 

 these are separated from one another in the middle line by the 

 palatines, and are bounded elsewhere by the maxillae, trans- 

 palatines, and pterygoids. 



The palatines (fig. 43, A, 3) are long and rather narrow 

 bones interposed between the maxillae in front and pterygoids 

 behind. They meet one another in a long suture and form 

 much of the posterior part of the palate, while the whole length 

 of their dorsal surface contributes to the floor of the narial 

 passage. The dorsal surface of each bone is also drawn out 

 on its outer side into a prominent ridge which forms much of 

 the side and roof of the narial passage, being in contact with 

 the vomer and pterygoid, and at one point by means of a short 



