TEE BONES. 



which forms part of the sphenoid sinus. The posterior border presents, above, 

 a rugged crest called the palatine, flattened from side to side, bent outwards, and 

 bordered at its base and inwards by a very narrow synarthrodia! surface, which 

 responds to the pterygoid bone. It is smooth and concave in its inferior half, 

 and forms, with that of the opposite side, a parabohc arch (palatine arch) which 

 circumscribes, below and at the side, the double guttural orifice of the nasal 

 cavities. 



Extremities. — The superior, flattened on both sides, is bevelled on the external 

 side to articulate with the subsphenoidal process. The 

 inferior, flattened from before to behind, is curved 

 inwards and united by simple suture with that of the 

 opposite bone. 



Structure and deveJopment. — This is a very com- 

 pact bone, developed from a single centre of ossifi- 

 cation. 



Differential Characteks in the Palatine Bone in 

 OTHER Animals. 



The principal distinctive feature of this bone in the different 

 domestic animals is due to the part it takes in forming the 

 arch of the palate. In this respect there are very great differ- 

 ences in various species, but in none of them is tliis part so 

 reduced as in Solipeds, in which the bone is scarcely equal to 

 one-fifth of tlie palatine surface. 



A. Ox, Sheep, G-oat. — Tlie palatine bone in these animals 

 is very developed, and noticeable for the considerable extent of 

 the palatine portion of its external surface. The palatine canal 

 is entirely channeled out in its substauce. The palatine crest, 

 very thin and elevated, is formed altogether by the posterior 

 border of the palate bone, the pterygoid, and the subsphenoidal 

 process. There is no excavation for the sphenoidal sinuses ; 

 but, instead, all that part of the bone which enters into the roof 

 of the palate is hollowed, but in the Ox only, by irregular 

 cavities which communicate with the maxillary sinus of the 

 same side. The nasal foramen is very wide. 



B. Camel. — The staphyline fissure is wide and deep ; the 

 palatine crest is very developed, and has two rugged depressions 

 at its base. The palatine canal is not included in the palate 

 bone ; it opens at the second molar. 



C. Pig. — The palatine portion is leas developed than in 

 Ruminants, for it forms less tlian one-fourth of the palatine 

 arch ; on the other hand, the orbital portion is very limited. 

 The palatine crest is rt-placed by a tuberosity, against which 

 rests, outwardly, the subsphenoidal process, and inwardly the 

 pterygoid bone. The union of these three parts constitutes, on 

 tlie posterior surface of the head, a thick and very remarkable 

 trifid projection or mamelon. 



D. Dog, Cat.— It is in the Carnivora that the palatine bones 

 are of greatest extent in their proper palatine portion, as they 

 constitute nearly one-half of the palatine arch. They have no 

 share in t)ie formation of the sphenoidal sinuses, but furnish a 

 small excavation to the maxillary sinuses. 



E. Rabbit. — The palatine bones resemble those of the Horse, 

 with regard to the part they play in forming the palatine arch. 

 The palatine canal opens also between the palatine and superior 

 maxillary bones, but the palatine crests are proportionately 



more developed than in Solipeds (Fig. 35). 



dog's head (posterior face). 



1, Occipital tuberosity ; 2, 

 occipital foramen ; 3, occi- 

 pital condyle ; 4, condyloid 

 foramen ; 5, styloid process 

 of the occipital ; 6, mastoid 

 protuberance ; 7, concave 

 temporo-maxillary articular 

 surface ; 8, supra-condy- 

 loid eminence ; 9, inferior 

 orifice of the parieto-tem- 

 poral canal ; 10, posterior 

 foramen lacerum ; 11, 

 ditto, anterior. On the op- 

 posite side at a is shown 

 the orifice communicating 

 with the Eustachian tube 

 and the tympanum ; at h 

 the passage for the carotid 

 loop. 12, Body of the 

 sphenoid ; 13, oval fora- 

 men ; 14, inferior orifice of 

 the subsphenoidal canal ; 

 15, pterygoid bone; 16, 

 nasal surface of the palate 

 bone; 17, palatine surface 

 of the same; 18, vomer; 

 19, supermaxillary bone ; 



20. 



incisive opening. 



