200 ANIMALS OF THE PAST 
from the jaw are bent directly downwards. 
No perfect skull of this creature has yet been 
found, but it is believed to have had a short 
trunk. For a long time nothing but the skull 
was known, and some naturalists thought the 
animal to have been a gigantic manatee, or sea 
cow, and that the tusks were used for tearing 
food from the bottom of rivers and for anchor- 
ing the animal to the bank, just as the walrus — 
uses his tusks for digging clams and climbing 
“epee jeapes se a Sate 
out upon the ice. In the first restorations of | | 
Dinotherium it is represented lying amidst 
reeds, the feet concealed from view, the head 
alone visible, but now it is pictured as stand- 
ing erect, for the discovery of massive leg- 
bones has definitely settled the question as to 
whether it did or did not have limbs. 
There is another hint of relationship in the 
upper tusks of the earlier mastodons, and this 
is the presence of a band of enamel running 
down each tusk. In all gnawing animals the 
front, cutting teeth are formed of soft dentine, 
or ivory, faced with a plate of enamel, just as 
the blade of a chisel or plane is formed of a 
plate of tempered steel backed with soft iron ; 
