146 FOSSIL MAMMALIA. 
the Tapir, sufficiently elongated to gather up 
roots from the ground. The septum of the nos- 
trils also being strong and bony, gives further 
indication of the presence of a powerful organ 
appended to the nose ; such an apparatus would 
have afforded compensation for the absence of 
incisor teeth and tusks. Having no incisors, 
the Megatherium could not have lived on grass. 
The structure of the molar teeth (PI. 5, Fig. 6 — 
11, and PI. 6, No. 1), shows that it was not car- 
nivorous. 
The composition of a single molar tooth resem- 
bles that of one, of the many denticules, that are 
united in the compound molar of the Elephant ; 
and affords an admirable exemplification of the 
method employed by Nature, whereby three 
substances, of unequal density, viz. ivory, ena- 
mel, and crusta petrosa, or ccementum, are 
united in the construction of the teeth of grami- 
nivorous animals. The teeth are about seven 
inches long, and nearly of a prismatic form (PL 
5, Fig. 7. 8). The grinding surfaces (PI. 5, Fig. 9. 
a. b. c. and PI. 6, Z. a. b. c.) exhibit a pecu- 
liar and beautiful contrivance for maintaining 
two cutting wedge-shaped salient edges, in good 
working condition during the whole existence of 
the tooth ; being, as I before stated, a modifica- 
tion of the contrivance employed in the molars 
of the Elephant, and other herbivora. The 
