448 THE ANTIQUITY OF MAN 
human skulls. In Eoanthropus the bizygomatic width 
is between 130 and 140 mm. ; the bicoronoid should be 
between 104 and no mm. In both reconstructions the 
latter is 104 mm. Thus, so far as regards coronoid and 
condylar widths, the mandible and skull are compatible. 
The aspect bi the lower jaw presented in the re- 
construction (fig. 166, A, B) gives us an opportunity 
of looking more closely into another of the peculiar 
features of Eoanthropus. Within the semi-circle of the 
lower teeth lies the tongue ; the space enclosed by the 
inner margins of the teeth may be named the lingual 
area. The larger the intradental area, the larger and more 
brutal the size of the tongue. If to the lingual space 
which lies within the teeth we add the area represented 
by their chewing surfaces, we obtain a means of 
estimating the degree to which the function of mastica- 
tion was developed. The area we have to estimate — 
the counterpart of the palatal area — lies within the outer 
margins of the teeth, and is bounded behind by a line 
drawn from the hinder end of the last molar tooth on one 
side to the extremity of the corresponding molar on the 
other side. In the original reconstruction (fig. 166, A) 
of the Piltdown mandible this area measured 78 mm. in 
length, 66 mm. at its greater width ; its total extent 
4880 mm.^ In the second reconstruction (fig. 166, B) the 
dimensions are : length 70 mm., width 64 mm. ; area 
3980 mm.- Let us see how those dimensions compare 
with those of anthropoid apes. The masticatory area finds 
its highest expression in the gorilla. In the male the 
dimensions are : length 97 mm., greatest width 64 mm. ; 
area 5600 mm.- In the female chimpanzee we meet with 
the opposite extreme as regards the size of masticatory 
area. To take an average example (fig. 165, A) : length 
67 mm., width 54 mm. ; area 3180 mm.^ Thus in 
the development of the masticatory system, Eoanthro- 
pus rises well above the lower anthropoid limit. The 
original reconstruction shows an area 720 mm. less than 
the male gorilla, and 1700 mm. more than the female 
chimpanzee. With a brain developed to the amount 
