THE SKELETON OF THE DOG. THE SKULL. 401 



through the foramen lacemm posterms (fig. 75, IX, X, 

 XI), a large space lying between the auditory bones and the 

 exoccipital. 



i. Finally, the twelfth nerve, the hypoglossal, passes out 

 through the prominent condylar foramen (fig. 75, XII), 

 which perforates the exoccipital just behind the foramen 

 lacerum posterius. 



II. OTHER OPENINGS IN THE SKULL. 



a. The anterior narial opening lies at the anterior end 

 of the skull, and is bounded by the premaxillae and nasals. 

 In the natural condition it is divided into two by a vertical 

 partition, formed by the narial septum, the anterior un- 

 ossified j5art of the mesethmoid. 



b. Penetrating the middle of the maxilla at the side of 

 the face is the rather large infra-orbital foramen (fig. 73, 11), 

 through which part of the second branch of the trigeminal 

 nerve passes out from the orbit to the side of the face. 



c. Several foramina are seen perforating the anterior part 

 of the orbit. The most dorsal of these, perforating the lach- 

 rymal bone, is the lachrymal foramen (fig. 73, 13). Lying 

 below and slightly external to this is a large foramen, through 

 which part of the second branch of the trigeminal enters on 

 its way to the infra-orbital foramen and so to the side of the 

 face. Lastly, lying below these, and perforating the palatine, 

 are two closely apposed foramina, the internal orbital 

 foramina, through which part of the first or ophthalmic 

 branch of the trigeminal nerve leaves the orbit, passing into 

 the nasal cavity. 



d. The anterior part of the palate between the premaxillae 

 and the maxillae is perforated by a pair of long closely apposed 

 apertures, the anterior palatine foramina (fig. 75, 19). 

 They transmit part of the trigeminal nerve. 



e. Towards the posterior part of the palate are two pairs 

 of small posterior palatine foramina (fig. 75, 18). These 



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