474 
THE ANTIQUITY OF MAN 
molar the pulp cavity tends to become situated more 
deeply as regards the upper or alveolar border of the ^i 
mandible ; (2) extensions of the pulp cavity are continued fl 
to the tips of the roots ; through the canals in the roots 
vessels and nerves reach the pulp cavity. 
When we compare those X-ray pictures of the lower 
molar teeth of anthropoids with skiagrams obtained 
from human mandibles certain differences become apparent 
GORILLA. 
10 20 30 'fO .W/ 
chimpanzee:. 
Fig. 174. — Tracings from skiagrams of the lower molars of a female gorilla 
and of a female chimpanzee. 
(fig. 175). If, for instance, a tracing of the molar teeth 
of Eoanthropus, as revealed by the skiagram published 
by Professor Underwood, is compared first with the 
tracings shown in fig. 174, and then with the various 
tracings of human molars shown in fig. 175, we cannot 
have any doubt as to the group to which the Piltdown 
molars must be assigned. They belong to the human 
group ; they are remarkably like the modern teeth 
shown in fig. 175. The roots of the Piltdown molars 
are not long, only about 12 mm. ; in modern molars 
a root length of 15 mm. is not unfrequently seen. The 
