TRANSACTIONS OF WAGNER 



T.6 



MASTODON 



Among the remains of the Florida Mastodon from Mixon's plantation, in 

 the collection of 1890, are four isolated specimens of teeth, which from their 

 general appearance are supposed to have pertained to the same animal, an indi- 

 vidual of nearly the same age as those to which the previously described speci- 

 mens belonged. They consist of the upper first and second true molars of the left 

 side, and the second one of the right side, and the lower left second true molar. 



The first and second upper molars, as represented in those of the left side 

 in plate i. fig. 4, pretty closely resemble the corresponding teeth already de- 

 scribed, both in construction and condition of wear, but are not quite so large. 

 In the first molar the constituent lobes of the crown are well worn away, and 

 the broad dentinal surfaces they display are on a level with the bottom of the 

 inner valleys. The dentinal areas of the anterior lobes of the crown are con- 

 joined by an isthmus, while the others are still separated by narrow necks of 

 enamel. Strong processes of the basal ridge unite the bases of the contiguous 

 inner lobes of the crown. 



In the second molars, that of the right side is most worn, and to such a 

 degree that dentinal areas are exposed on all the constituent lobes of the crown, 

 while in the left one they are not exposed on the posterior pair of lobes, and 

 of these the outer one is scarcely worn. In these teeth the inner lobes of the 

 crown rather more conspicuously embrace the outer ones than in the same teeth 

 previously described, and the internal basal ridge is more coarsely tubercular. 



The measurements of the teeth are as follows : 



Fore and aft diameter of the crown of the first molar . . 103 mm. 



Transverse diameter at base of anterior lobes . . . 65 " 



Transverse diameter at base of posterior lobes ... 65 



Fore and aft diameter of the crown of the second molar . 136 " 



Transverse diameter at base of anterior lobes . . . 84 " 



Transverse diameter at base of posterior lobes . . . 86 " 



The second lower true molar tooth, represented in plate i. fig. i , has the 

 crown shorter fore and aft than the corresponding upper tooth, is also nar- 

 rower transversely, and is of less uniform breadth, being narrowed forward. 

 It is, further, more worn, as considerable dentinal areas are exposed on the 

 summit of the last outer lobe and its anterior buttress, and minute ones on the 

 contiguous inner lobe. The outer constituent lobes of the crown are closely 



o 



like their homologues of the upper molars, but the inner lobes appear propor- 

 tionately less wide transversely. The talon forms a conspicuous pair of large 

 conical eminences at the back of the crown. 



