TBE HEAD. 



65 



inferior extremity, at tlie junction of the supermaxilla with the palatine bone. The maxillary 

 sinus is not very spacious, and there is no maxillary spine (Fig. 29). 



E. Rabbit. — The superior maxilla in this animal is less extensive, proportionately, than 

 that of the other animals. The external table is thin, and even cribriform. The malar tubercle 

 is narrow and directed outwards. The palatine process is very narrow, and therefore only 

 very slightly concurs in the formation of the arch of the palate ; it does not extend to the 

 summit of the internal process of the incisive bone (Fig. 36). 



Fig. 37. 



ox's HEAD (POSTERIOR FACE), 



A, Parietal bone: 1. occiintal foramen; 2, occipital condyle; 3, styloid process of that bone; 

 4, condyloid foramina; 5, mastoid process; 6, mastoid protuberance; 7, subuliform (temporal) 

 process; 8, hyoideal sheath ; 9, stylo-mastoid foramen ; 10, external auditory hiatus ; 11, inferior 

 orifice of the" parieto-temporal canal; 12, temporal condyle; 13, posterior foramen lacerum ; 

 14, oval foramen ; 17, subsphenoidal process ; 18, orbital hiatus ; 19, optic foramen. B, Frontal 

 bone : 20, supra-orbital foramen ; 21, orbital foramen ; 22, lachrymal protuberance. C, Malar bone : 

 23, pterygoid bone, d. Palatine bone : 24, nasal foramen ; 25, inferior orifice of the palatine 

 canal. E, Supermaxillary bone : 26, maxillary spine. G, Premaxillary bone : 27, its internal 

 process ; 28, external process ; 29, incisive openings. 



2. Premaxillaey, Inteemaxillary, or Incisive Bone (Figs. 26, 38). 



This bone occupies the inferior extremity of the head, and is composed of a 

 thick prismatic jwrtion, lengthened superiorly by two long processes. 



Thick portion or base. — This presents a solid mass with three faces : an 

 external or labial, smooth and convex : an internal, denticulated for union with the 

 opposite bone, and traversed from before to behind by an inflexed fissure, which 

 forms, with an analogous one in the other premaxilla, the incisive canal or fora- 

 men incisivum ; the third or posterior, also called the buccal, is slightly concave, and 



