THE TEETH. 357 



has generally the following distinctions : the disto-lingual 

 cusp is more rudimentary; the disto-lingual fissure does 

 not run over on the lingual side, and the roots have a 

 tendency to stand closer together. 



The third superior molar is the smallest; it has three 

 cusps separated by fissures, which terminate in the centre 

 in a depression. The roots have a still greater tendency 

 to come together, and are often confluent. 



The inferior first molar has five cusps, three buccal 

 and two lingual, separated by fissures, one running 

 mesio-distally and one from this fissure lingually sepa- 

 rating the last-mentioned cusps, and two running from 

 the mesio-distal fissure, separating the three buccal cusps. 

 It has two roots, an anterior and posterior, of which 

 the first is the larger and flatter. 



The inferior second molars differ from the first in 

 having only four cusps and a crucial fissure, which gen- 

 erally extends over on the buccal surface and terminates 

 near the gum in a depression. The roots have a tend- 

 ency to curve backward. 



The third inferior molar is very much like the first, 

 except that the roots have even a greater tendency than 

 those of the second to curve backward, and are more 

 confluent. 



Temporary Teeth. The temporary teeth are smaller, 

 but closely resemble, in form, those of the permanent 

 set. The enamel terminates abruptly, and is the dis- 

 tinguishing feature when in doubt. The crown of the 

 upper first molar has usually three cusps; the upper 

 second, four ; the inferior first molar, four ; and the 

 second, five. 



Structure of Teeth. On dissection we find a tooth 

 to consist of pulp, dentine, enamel, cementum, and the 

 pericementum or peridentium. 



