140 
FOSSIL MAMMALIA. 
the Tapir, sufticiently elongated to gather up 
I’oots 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 incisorSj 
the Megatherium could not have lived on grass- 
The structure of the molar teeth (PI. 5, Fig. 6--^ 
1 1, 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 ai’O 
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 criista petrosa, or ccementum, are 
united in the construction of the teeth of gram^' 
nivorous animals. The teeth are about sevei^ 
inches long, and nearly of a prismatic form (P^‘ 
5, Fig. 7. 8). The grinding surfaces (PI. 5. Fig- 
a. b. c. and PI. 6, Z. a. b. c.) exhibit a pecu- 
liar and beautiful contrivance for maintainiu^ 
two cutting wedge-shaped salient edges, in gue^ 
working condition during the whole existence uf 
the tooth ; being, as I before stated, a modified 
tion of the contrivance employed in the molar® 
of the Elephant, and other herbivora. "Th® 
