490 SPECIAL PHYSIOLOGY. 



a minute tubercle. The groove on the fang, and this posterior tubercle, 

 foreshadow the subdivided fang and double crown of the bicuspid teeth. 

 The canine teeth are so named from their large size in the dog, though 

 they are still larger in the great feline animals; in Man, they are 

 more uniform in size with the neighboring teeth, than in the larger 

 Quadrumana and Carnivora. From their single point or cusp, which 

 wears down with use, these teeth are sometimes called the cuspidate 

 teeth. The bicuspid teeth, b, sometimes called premolars, because 

 they are placed before the molars, and also named the small or false 

 molars, have a double crown furnished with two pointed cusps or tuber- 

 cles ; viz., an outer higher, and an inner lower one, between which is 

 an irregular depression. The summit of the crown is quadrangular, 

 and compressed from side to side, contrasting with the pointed canines, 

 and chisel-shaped incisors. The fang, in the lower bicuspids, is deeply 

 grooved on each side, but in the upper ones, is cleft for a certain dis- 

 tance at the point. The molars or grinding teeth, m, are the largest 

 of the entire set ; the first on each side of each jaw, are the largest, 

 and the third, or last molars, which are also named the wisdom teeth 

 (dentes sapientiae), from their late appearance, are the smallest. They 

 have a large, nearly cuboid crown. In the upper molars, this presents 

 four cusps or tubercles, placed at the angles of the upper surface, and 

 separated by a crucial depression ; the first and second of these teeth 

 have the internal anterior tubercle always the largest; in the last upper 

 molars, the two internal tubercles are blended. The crowns of the 

 lower molars are larger than those of the upper, and are distinguished 

 by having a fifth small cusp or tubercle placed between the outer and 

 inner posterior cusps, rather nearer to the former than to the latter ; 

 this fifth cusp is best marked in the last lower molar tooth. The 

 grinding surface of the lower molars is nearly square ; that of the 

 upper, rhomboidal. In the lower jaw, the two anterior molars have 

 two fangs, but these are broad, grooved on their surface, and some- 

 times subdivided at their points. In the upper jaw, the fangs of the 

 two anterior molars are three in number, two outer and one inner fang, 

 the latter being sometimes grooved or even subdivided. The fangs of 

 the upper molars are more divergent than those of the lower ones. In 

 the wisdom teeth, or last molars of each jaw, the fangs are generally 

 connate or united into a mass, showing marks of subdivision into two 

 fangs in the lower teeth, and three in the upper. 



The row of teeth, in each jaw, forms what is called the dental arch. 

 In Man, it presents a broad, even curve, the upper dental arch being 

 larger than the lower, so that usually it overlaps the latter when the 

 teeth are closed, and thus saves the edges of the incisor teeth from un- 

 necessary wear. The upper front teeth are inclined slightly forwards, 

 and the back teeth outwards; whilst the lower front teeth are vertical, 

 and the lateral teeth directed somewhat inwards, an arrangement which 

 corresponds with the greater size, and the overlapping of the upper 

 dental arch. In Man, the entire series of teeth are characterized by 

 being uninterrupted by any marked interval, hiatus, or diastema, and 

 by their nearly even height, which however diminishes slightly from 

 before backwards. In Mammiferous animals, the teeth are either of 



