30 



THE CAT. 



[chap. II. 



week. They begin to fall out after tlie seventh month, but the 

 lower true molar comes into its place before the deciduous molars 

 fall out. In shape the upper incisors are like their permanent 

 successors, save that the transverse furrow is less marked. The upper 

 canines are smaller and less grooved than the permanent ones 



The first upper deciduous molar is a 



small, simple one-fanged 

 tooth like its vertical suc- 

 cessor. The second de- 

 ciduous molar is quite 

 unlike the tooth which 

 replaces it, but nearly 

 resembles the third 

 upper premolar or sec- 

 torial. Its outer cutting 

 part, or blade, is three- 

 lobod, but both the an- 

 terior and posterior lobes 

 are notched, and the in- 

 ternal tubercle, which is 

 relatively larger than in 

 the permanent sectorial, 

 is continued from the 

 base of the middle lobe. 

 There are three fangs, 

 but the inner fang is 

 more opposite the inter- 

 space between the two 

 outer fangs than is the case in the true or permanent sectorial. 



The third upper deciduous molar is again quite difierent from the 

 tooth which succeeds it, while it resembles the true or tubercular 

 molar of the upper jaw, save that its relative size is larger. 



The first deciduous lower molar is like the second premolar, while 

 the second deciduous molar is like the inferior sectorial, with a 

 relatively smaller anterior lobe and a much larger posterior tubercle, 

 or talon, which is notched so as to form two small posterior tubercles 

 at the base behind the posterior and greater lobe. 



§ 18. Such being the dentition {i.e. tooth-furniture) of the cat, it 

 may be conveniently expressed by the following symbols 



Fi^. 13.— The Cat's Milk Dentition, enlarged. 



Below, the true molar is seen much advanced, and soon 

 to rise behind the second lower deciduous molar. In 

 the upper jaw the jierniatient ui)per .sectorial is secii 

 in an advanced state of development above the third 

 deciduous molar. 



If 



PMf 



Uj for the second, or permanent dentition. 



means " three incisors, above and below, on each side of the jaws ; " 

 c-j- means similarly, " one canine on each side of each jaw ; " pm^ 

 means " three premolars on each side of the upper jaw and two on 

 each side of the lower jaw ; " and M-j- means " one true molar both 

 above and below on each side." Similarly, the symbols di}, nc|, 

 DZkif for the milk dentition, refer in the same manner to the 

 deciduous incisors, canines, and molars respectively. 



It need hardly be added that each tooth attains its full develop- 

 ment within a limited time, after which it grows no more, and no 

 third development ever replaces the fall of a tooth of the permanent 

 dentition. 



