THE ALLIGATOR'S LIFE HISTORY 67 



No. 4, is the top of upper left tenth tooth the base of 

 which has almost been absorbed. Only a very small part 

 of this tooth was still in the jaw socket, the rest having 

 been absorbed, and the tip held in place by the gum would 

 have soon been pushed out by the new tooth growing up. 



No. 5, is the new upper left tenth tooth which was in 

 place under number four. 



No. 7, is tip or cap of upper front fourth tooth whose 

 below the gum surface has been almost completely ab- 

 sorbed, the tip shown being held in place only by the 

 gum. 



No. 8, is new upper left front fourth tooth about one- 

 half developed which was growing under top or cap num- 

 ber seven, and almost ready to take its place. 



No. 9, is the upper right fourth tooth fully developed, 

 and showing a small thin egg-shaped space near its inside 

 base at which point absorbation of the tooth's bony 

 structure begins as the new tooth develops inside, the tiny 

 cap of a new tooth is in place inside this tooth. 



There are often tips of three new teeth under each other 

 and inside the hollow base of the old tooth. As the jaw 

 grows and the old teeth become too small for their sockets 

 the hollow bases up to the exposed solid points are ab- 

 sorbed and disintegrated while still in place and the new 

 teeth growing up have nothing to push out, but push off 

 the solid caps which are the only part of the old teeth 

 really shed. 



When an alligator becomes fully grown, its teeth give 

 evidence of maturity by becoming almost solid; that is, in 

 growing alligators, the teeth are hollow and changed often. 

 In fully-grown specimens the teeth are no longer changed, 

 and are solid almost all the way down. This is the only 

 way I know of by which a fully-grown alligator can be dis- 

 tinguished from one not yet mature. 



All the teeth of the upper jaw overlap the teeth of the 

 lower jaw, and when the jaws are closed the teeth of the 

 lower jaw are completely hidden by those of the upper jaw. 



The fourth tooth from the front on each side of the 



