CHAP. XIV.] 



ALIMENTATION. 



157 



Beginning in the middle line of each jaw and counting from 



before backwards, there are four incisors, two canines, four 



bicuspids, and six molars in the upper and in the lower jaw. 



The incisors have wide sharp edges, and are specially adapted 



for cutting the food ; the canines, or eye teeth, have a sharp 



pointed edge, are longer than the incisors, and are specially 



useful for tearing food asunder, 



or, as in dogs and other car- 



nivora, for holding prey. The 



bicuspids, or false grinders, are 



broader, with two points or cusps 



on each crown : these teeth have 



only one fang, the fang, however, 



being more or less completely 



divided into two. The molars, 



or true grinders, have broad 



crowns with small pointed pro- 



jections, which make them well 



fitted for crushing and bruising 



the food : they each have two or 



three fangs. The twelve molars 



do not replace the milk teeth, but 



are gradually added with the 



extension of the jaws, the last or 



hindermost molars not appearing 



until twenty-one years of age: 



777, 



FlG . ,._!,, MOUTH, NOSE 



they are often on this account PHARYNX, WITH THE LAKYNX AND 



"wisdom fppth " 

 Cl1 ' 



The 



COMMENCEMENT OF GULLET, SEEN 

 IN SECTION, a, vertebral column ; 6, 



teeth are composed of gullet; c, trachea; d, larynx; e, epi- 



three bone-like tissues, enamel, tt'&'XEfSttZ 



dentine, and cement; these Sub- fauces; <?, opening of Eustachian tube; 

 -1 -i j ,-1 i h, nasal cavity; k, tongue; /, hard 



stances are all harder than bone, palate; m> sphe noid bone at base of 



enamel being the hardest tissue skull; n, roof of nasal cavity ; o,p, q, 

 j, ,. ,, ,, T j i -A placed in nasal cavity. 



found in the body. In the inte- 



rior of each tooth is a cavity, the pulp-cavity, which is filled 

 with a highly vascular and nervous tissue called the dental pulp. 

 The teeth are developed from epithelium in much the same way 

 as the hairs; for description of which see page 192. 



The pharynx. The pharynx or throat cavity is a musculo- 

 membranous bag, shaped somewhat like a cone, with its broad 



