THE LOWER JAW. 69 



9. The PTERYGOID are two thin plates of bone, placed 

 behind the palate bone, and at the base of the cranium. 



1. The LOWER JAW {SkeL B), or inferior maxillary, is 

 sufficiently described in other parts of this work. 



2. The VOMER lies upon a groove upon the upper surface 

 of the palatine portion of the superior maxillaries, and is itself 

 deeply grooved for the reception of the cartilaginous nasal 

 septum {Plate VI. a), the entire bone being within the nose. 



THE LOWER JAW. 



The mouth is formed by the two jaws conjointly (Plate 

 VII. c), and in each is fixed an equal number of teeth, viz. 

 six grinders on either side, or twelve in each jaw {Skel. c) ; 

 two tushes in each jaw, or four in both {Skel. b) ; six nippers 

 or incisors in each jaw, or twelve in the two {Skel. a), making 

 altogether forty teeth. The lower jaw constitutes the base 

 of the mouth, and on the outer side of it are placed several 

 glands which pour forth a large quantity of saliva during 

 the time the animal is eating. The use of this fluid thus 

 emptied upon the food which is being masticated between 

 the teeth is to render it moist, so that it may ultimately 

 become a soft mass, and be in a state fit to be swallowed. 

 Within the large branches of the lower jaw are contained 

 the tongue, the fauces, the pharynx, the hyoidal bone or bone 

 of the tongue, part of the larynx, and some glands, the use 

 of all and each of which, for none are useless, we shall have 

 to point out in their proper places hereafter. 



The upper jaw, beside containing half of the teeth, forms 

 the top of the mouth, on which are formed certain indenta- 

 tions running from side to side, the projecting parts being 

 termed the bars {Plate VII. i). From the middle of the 

 upper jaw hangs down the soft palate {Plate VI. /, and Plate 

 VII. I), which constitutes the back of the mouth. The soft 

 palate rests upon the posterior part of the tongue {Plate 

 VI. e). Being attached to the upper jaw shghtly forward, as 

 w^el] as in a crescentic form, it slopes backward to its resting 

 place ; thus situated it forms a barrier to any substance 

 passing into the mouth which is ejected by the stomach ; 

 but allows any thing to pass W'ith perfect ease which may 

 be propelled from the mouth towards the stomach. The 

 sides of th^ movith consist of flesh which, on its inner surface, 



