286 SKELETON OF THE EABBIT 



upwards into the orbital process, forming the 

 anterior boundary of the orbit. In front, the 

 maxilla is prolonged into the large fenestrated 

 facial plate, which forms the lateral bound- 

 ary of the olfactory chamber, and is per- 

 forated just above the first grinding tooth by 

 the infra-orbital foramen, for the passage of 

 the maxiUary division of the trigemiual nerve. 



iv. The premaxillcB are a pair of bones, forming the 

 anterior part of the upper jaw, and lodging the 

 incisor teeth : they articulate with the maxillae 

 behind, and with each other in the median 

 plane in front. 



The upper and posterior angle of each 

 premaxilla is produced backwards into a 

 long nasal process, which lies along the outer 

 border of the nasal bone, and above the 

 maxiUa and the anterior process of the frontal. 

 On the under surface of the skuU, bounded 

 laterally by the premaxillse and maxiUfe, 

 and behind by the hard palate, is a large tri- 

 angular aperture, divided longitudinally into 

 the slit-Uke anterior palatine foramina by 

 the palatal processes of the premaxillge, a pair 

 of thin, longitudinally roUed laminse attached 

 in front to the premaxillse, and enclosing the 

 accessory organs of smell known as Jacobson's 

 organs. 



v. The jugals are a pair of laterally compressed bars 

 forming the greater part of the length of the 

 zygomatic arches, which bound the orbits 

 below. Their anterior ends are fused with 

 the zygomatic processes of the maxillae, and 

 posteriorly they articulate along their dorsal 

 edges with the squamosals. 

 To. Bones in relation with the mandibular arch. 



The uppermost part of the mandibular arch 

 gives rise to the incus and malleus, which have 



