The American Naturalis 
molars heteromerous ; 
Superior incisors without enamel-band. 
Elephas Linn. 
The characters assigned to the above genera are sufficient 
to separate them, but they have not come into general use for 
two reasons. One is the difficulty of verifying some of them, 
especially the presence of premolars, owing to the difficulty 
of obtaining specimens of young individuals. The other is the 
indisposition of naturalists to abandon the system of Falconer. 
As is well-known, this able paleontologist distinguished the 
genera by the number and depth of the transverse crests of 
the molar teeth, and the extent to which their interspaces 
are filled with cementum. This arrangement is insufficient, 
since it neglects the equally important characters above 
Fig. 3. Longitudinal sections of the molar teeth of Proboscidia, much reduced, 
From Gaudry. Letters; <■ cementum ; </ dentine; e enamel. A, Inferior molar of 
Dinotherium giganteum Cuv. B, superior molar of Mastodon americanus Cuv. 
C, lower molar of Elephas ganesa C. F. D, do. of Elephas insignis C. F. E, do. of 
Emmenodon planifrons C. F. F, do. of Elephas hysudricus C. F. G, do. of Ele- 
iGen. 
r. Type Elephas cliftii 
Mastodon elephantoides Clif 
