190 
THE TERTIARY AGE, AND 
comparison with that animal as the next step in 
the investigation, when it was found that at the 
edge of the lower jaw of the latter there was a 
pit with a small projecting tooth, also correspond- 
ing exactly in its position to the tusk in the Di- 
notherium. The Elephant was now examined ; 
and in him also a rudimentary tooth appeared in 
the lower jaw, not cut through, but placed in the 
same relation to the jaw and the other teeth as 
that of the Mastodon. It would seem, then, that 
the Manatee makes one in this series of Dinothe- 
rium, Mastodon, and Elephant, and represents 
the aquatic Pachyderms, occupying the same re- 
lation to the terrestrial Pachyderms as the Seals 
bear to the terrestrial Carnivora, and, like them, 
lowest in structure among their kind. 
The announcement of Cuvier’s results stimu 
lated research, and from this time forward Ter- 
tiary Mammalia became the subject of extensive 
and most important investigations among natu- 
ralists. The attent'on of collectors once drawn 
to these remains, they wo^e found in such num- 
bers that the wonder was how they had been so 
long hidden from the observation of men. They 
remind us chiefly of tropical animals; indeed, 
Tigers, Hyenas, Rhinoceroses, Hippopotamuses, 
Mastodons, and Elephants had their home in 
countries which now belong to the Cold Temper- 
ate Zone, showing that the climate in these lati 
