106 COMPARATIVE DENTAL ANATOMY 



form in different individuals, and also in the same 

 individual at different times. They are small in 

 front and increase in size to the side, and then 

 diminish toward the back. The Crocodile differs 

 from the Alligator partly by the presence of the 

 notch on the side of the muzzle into which the 

 so-called lower "canine" passes, instead of the 

 fossae of the Alligators. Both Crocodiles and Al- 

 ligators are remarkable for the breadth and flat- 

 ness of the muzzle and for the alternate increase 

 and decrease of the teeth in the series from front 

 to back. The alligator of the Mississippi has 

 eighteen to twenty-two teeth on each side of the 

 upper jaw. The teeth in front of the premaxil- 

 lary bones are the smallest. These increase in 

 size to the fourth, which is nearly twice as large 

 as the others ; the first of the maxillary teeth are 

 the smallest; the third is the largest, — the so- 

 called "canine," — the ninth tooth from the me- 

 dian line. The eighth and tenth are sometimes 

 as large or larger than the ninth. The teeth then 

 decrease in size, then increase again to the seven- 

 teenth, then decrease to the end of the series. 

 The posterior teeth are sub-compressed, with a 

 more or less rounded eminence. The teeth of the 

 lower jaw are likewise of unequal proportion, the 

 smallest and largest alternating with the smallest 

 and largest above. The largest caniniform tooth 

 below is received into a deep fossa just inside of 



