THE TEETH 



403 



ciduous teeth begin to be pushed out by the eruption of the second or 

 permanent set. 



The permanent teeth number thirty in all. On each side, above 

 and below (Figs. 318, 319), the three permanent incisors and the single 

 permanent canine replace the deciduous incisors and the deciduous 

 canine. On each side above, three permanent teeth replace the 

 deciduous molars. Inasmuch as they are situated in front of the fourth 

 permanent molar, which has no predecessor in the milk set, they are 



FIG. 318. 



Frontal., 



Nasal 



Upper Anterior part of 

 Ethmo-tuiiiiittil. 



Maxillo-turbinal. 



Cut edge of Cribriform plate 

 of Ethmoid. 



Lower Posterior part 

 of Ethmo-turbinal 



\ in SiJius. 

 ~ Vertical Longitudi- 

 R a, c.'^i nal Partition 



-dal Smus. 



Premaxillary. 



Vertical 

 plate of 

 Palatine. 



Horizontal plates 

 of Mnxil/nrii 

 and Palatine. 



Vomer. 



RIGHT UPPER TEETH IN POSITION, MEDIAL VIEW. 



called premolars. The student should remember that all the milk 

 teeth behind the canines are known as deciduous molars, but that in 

 the permanent set the molars are such only as have no deciduous pre- 

 decessors. In the lower jaw on each side, two permanent premolars 

 replace the two deciduous molars, and a new permanent molar appears 

 behind them. 



We express the double dentition of the cat by the following 

 formulae, in which d stands for deciduous, i for incisor, pm for pre- 

 molar, and m for molar ; the numerator of the fraction represents the 



