THE HEAD. 



67 



cavity. The incisive opening is very small, and the external process does not reacli the 

 nasal bone. 



C. Pig. — III the Pig, the external process of the preiuaxiliary bone is very long and wide 

 at its base, and cons>li(lated with the nasal bone for about the upper two-thirds of its length. 

 There is no incisive foramen or cavity for the tusk, The incisive openings are oval. 



D. Dog, Cat. — Of small size, the premaxilla of Carnivora has no incisive foramen or 

 alveolar cavity for the canine tooth. The incisive open- 

 ings are the same as in the Pig. Fig. 39. 



E. Rabbit.— Proportionately voluminous, the pre- r ^ 

 maxilla of the Rabbit is remarkable for the great de- *^ " 

 velopnient of its ascending processes, which reach the f'JL^^ ^^^j^^^^ f 

 frontal bone, and the width of the incisive slits, which 

 are confounded above the internal processes. It carries 

 two incisors, placeil one before the other. 



3. Palatine Bones (Fig. 38). 



The folate or palatine, bones are situated be- 

 tween the supermaxillaries, at the margin of the 

 guttural opening of the nasal cavities, and are 

 articulated with the sphenoid, ethmoid, vomer, 

 frontal, and pterygoid bones. Elongated from 

 above to below, flattened laterally, and curved 

 towards each other at their inferior extremity, 

 which is flattened from before to behind, these 

 bones, though irregular in shape, offer for study 

 tivo faces, two borders, and two extremities. 



Faces. — The external face of the palate bone 

 is divided into three fractions — a superior, or 

 orbital, an inferior, or palatine, and a middle, or 

 articular. The first is smooth and slightly ex- 

 cavated, and participates in the formation of the 

 maxillary hiatus : it shows a small groove, the 

 staphi/loid, which reaches the palatine fraction 

 in passing between the posterior border of the 

 bone and the alveolar tuberosity. The second is 

 not extensive, and looks backwards in conse- 

 quence of the antero-posterior flattening which 

 the bone presents at its inferior extremity ; it 

 forms part of the roof of the palate. The third 

 presents a lamellar and denticulated surface 

 which corresponds to a similar face on the 

 supermaxillary bone, and is channeled from 

 above to below by the internal groove of the 

 palatine canal. 



The internal face, smooth and concave, forms 

 part of the external wall and the floor of the 



HEAD OF THE PIG (POSTERIOR FACE). 



1, Occipital tuberosity ; 2, occipi- 

 tal foramen ; 3, occipital con- 

 dyle ; 4, condyloiil foramen; 5, 

 basilar process ; 6, 6, mastoid crest; 

 7, styloid process of the occipital 

 bone ; 8, articular surface of the 

 temporal bone ; 9, mastoid protu- 

 berance ; 10, foramen laoerum; 11, 

 subsphenoidal })rocess — external 

 wing of pterygoid process ; 12, 

 palatine crest ; 13, pterygoid bone 

 (internal wing of the i)terygoid 

 process) ; 14, inferior orifice of the 

 palatine canal ; 15, 15, incisive 

 openings. 



nasal fossa. 



Borders. — The anterior is indented, near its superior third, by a deep notch, 

 which is often converted into a foramen, the nasal. Below this notch the bone 

 is thin and denticulated for union with the supermaxillary bone ; above, its two 

 plates separate widely from one another, giving rise to a very spacious cavity 



