172 



SKELETON OF THE PIG 



maxilla. In the adult the frontal sinus extends into the posterior part of 

 the bone. 



The lacrimal bone is very sharply bent. Its facial surface presents a deep 

 depression, surmounted by a ridge or tubercle. On or close to the orbital margin 

 are two lacrimal foramina which lead to the lacrimal canals. The orbital surface 

 presents a fossa in which the inferior oblique muscle of the eyeball arises, and its 

 lower part bears a crest, which is crossed obliquely by a vascular furrow. The 

 dorsal border articulates with the frontal only. The bone concurs in the formation 

 of the maxillary sinus. 



The malar bone is strongly compressed from side to side. Its facial surface 



is small and presents a fossa which is con- 

 tinuous with the depressions of the maxilla 

 and lacrimal. The orbital surface is still 

 smaller and is smooth and deeply grooved. 

 The zygomatic process is very extensive, 

 especially in the vertical direction. Its 

 lateral surface is convex and free, and 

 bears a rough eminence in its middle. Its 

 medial surface is concave; it is over- 

 lapped in front by the maxilla, and in the 

 remainder of its extent is free and smooth. 

 The dorsal border is thick and rounded in 

 front, where it forms the lower part of the 

 orbital margin; behind this it forms an 

 extensive notch which receives the zygo- 

 matic process of the temporal. (It might 

 be regarded as dividing into frontal and 

 temporal branches.) The ventral border 

 is convex and becomes thinner behind. 



The turbinate bones resemble those 

 of the ox. The dorsal turbinate is, how- 

 ever, relatively longer, less fragile, and 

 more firmly attached to the nasal bone. 

 There is no middle turbinate. 



The vomer is very long. The anter- 

 ior extremitj' reaches to the body of the 

 premaxilla or very close to it. The ven- 

 tral border is received into a groove 

 formed by the nasal crest of the maxillee 

 and palatine bones and in front by the 

 palatine processes of the premaxillse. The 

 posterior border is concave, thin, and 

 sharp. 



The OS rostri (or prenasal bone) is 

 situated in the snout between the nostrils. 

 It has the form of a short, three-sided prism. The dorsal surface is convex and is 

 notched at each end. The lateral surfaces are concave, smooth, and converge 

 below, forming a grooved ventral border. The posterior surface is triangular, 

 notched centrally, and rough laterally. The anterior surface is deeply pitted and 

 is surrounded by an irregular sharp border. 



The mandible is very strong, and differs very much from that of the horse or 

 ox. The body narrows decidedly in front; the lingual surface is deeply concave; 

 the mental surface is strongly convex, slopes downward and backward, and forms 

 a distinct prominence (Tuber mentale) at the point of divergence of the rami. 



Fig. ISl. — AIaxdible of Pig; Dorsal View. 

 A, Body; B, B' , horizontal and vertical parts of 

 ramus; C, condj'le; D, coronoid process; 1, 2, 3, in- 

 cisor teeth; 4, canine tooth; 5, 6, 7, premolar teeth 

 (first absent) ; S, 9, 10, ntolar teeth. 



