THE MOUTH. 427 



stand up to form a grip, resting against the pad on the upper jaw much more by their extremity 

 than by their inner surface. 



They are, besides, narrow, have scarcely any neck, and are fixed more solidly in the alveoli 

 (Fig. 237). 



Their external face is white and polished, and is encased towards the gum in a kind of 

 black cement. 



The internal face has two wide, longitudinal grooves, separated towards the middle of the 

 table by a simple ridge, wliich replaces the conical eminence of the Ox's incisor. These 

 grooves are nearly always lined with the black cement-like substance. 



The incisors of the Sheep are, like the Ox's, dititinguished into temporary and replacing 

 teeth ; the first are known from the others by their smallness, and particularly by their 

 narrowness. 



The wear of the incisors in the Sheep, from their position, ought to take place nearer the 

 anterior border than in the Ox; the dental star is observed 

 earlier, and always forms a narrower line from before to behind. pjg. 237. 



The absence of a neck in these teetli is the reason why they 

 never appear to separate with wear, as has been remarked in 

 those of the Ox. 



The molars have tlie greatest resemblance, in their general 

 form and relative proportions, to those of the Ox. 



The teeth of the adult Camel are thirty-four in number — 

 six incisors in the lower maxilla, ten molars, and six teeth re- 

 sembling canines, two of which are fixed in the premaxilla. In incisor teeth of a sheep 

 the young animal, the incisors— the free border of whicii is sharp '^^^ years old. 



as in the otiier Ruminants — are much inclined on the maxillary The second laterals and the 

 border, but become erect as the creature grows older, so as to corner incisors have not 

 resemble those of the Horse. yet been replaced. 



The canines of the lower jaw are strong and pointed ; among 

 those of the upper jaw, the laterals only are greatly developed, and some authorities regard 

 them as premolars. 



Tile proper molar teeth show the general arrangement and organization of the Ox's teeth. 

 They are covered by a dark cementum (Fig. 46). 



Pig 1. Li'ps — In this animal the lips are widely cleft. The lower is pointed and little 

 developed; tlie upper is confounded with the snout, which will be described with the nostrils. 

 (The upper lip has little mobility.) 



2. Cheeks. — Tliese are small and thin, and the mucous membrane smooth. 



3. Palate. — Narrow and elongated, it is disposed as in the Horse. In front is seen the 

 orifices of Jacobson's canals. (The transverse ridges are twenty to twenty-two in number, the 

 anterior being larger than the posterior, and their free borders are united.) 



4. Tongue, f^. Soft Palate. — These two organs are the same as in the smaller Ruminants, 

 except that the filiform papillae are perhaps less developed. (The isthmus of the fauces is 

 circular, and the posterior pillars are confounded with the mucous membrane at the upper part 

 of the oesophagu-^. Its anterior surface has several conical eminences in the middle, and the 

 amygdalae iire little rounded elevati(ms.) 



6 Teeth. — The Pig has forty-four teeth, which are divided into twelve incisors, four 

 canines, and twenty-eight molars (Fig. 238). 



The incisors, six in each jaw, exhibit very remarkable differences between each other. 

 The centrals and laterals of the upper jaw offer, by their form and the cavity they show on 

 their table, some analogy to those of the Horse. In the lower jaw, these teeth are straight, 

 directed forwards, and bear some resemblance to the incisors of rodent animals. The corner 

 incisors of botli jaws are isolated between the lateral and canine teeth, and are not nearly so 

 voluminous as the other incisors. 



The tusks are very developed, particularly in the male, and cross each other during the 

 life of the animal ; ihey project from the mouth, and form a very dangerous weapon in the 

 wild boar. The primary canines are deciduous, like the incisors. 



The molars, seven in each row, increase in volume from the first to the last, which Is very 

 strong. Their tables hold a middle place, with regard to arrangement, between that of the 

 Carnivora and Herbivora. 



Carnivora. 1. Lips.— The Carnivora, like the Pig, do not use their lips to grasp their 

 food, and these are therefore thin, though movable. The upper lip of the Dog has a groove 

 in the middle line, and it covers the lower lip more or less at the sides according to the breed. 

 The lower lip is always scalloped on its free border near the commissures, which are very high. 



