36o 
THE ANTIQUITY OF MAN 
when we attempt to build up the right and left sides 
of the skull, the parietal fragments must be so placed 
that the corresponding points of the right and left parietal 
bones match each other on the two sides of the skull. 
Our procedure is based on the fact that the skulls of all 
animals are built on a symmetrical plan — the right and 
left halves being alike, except in minor details. By a 
reference to fig. 119 it will be seen that the designers of 
this experiment had succeeded in reproducing a close 
parallel of the Piltdown problem. 
The next step in the solution of the problem is shown 
in fig. 126. The 
l^^frj left parietal frag- 
ment being the 
more complete is 
the 
be- 
ing replaced by 
plasticine or 
modeller's wax. 
The left half of 
the skull 
V£RT£)( 
RIGHT 
first built up, 
missing parts 
JO 20 30 40 50 V--"^ 
Fig. 125. — The right parietal fragment (stippled) of th 
in 
which form the 
employed in the 
are viewed in profile. 
up on a 
marked 
is built 
board, 
with 
test skull, superimposed on the left pariVtal, to bring measured lillCS 
out the corresponding points of the two sides. ' 
represented by 
those shown in fig. 126. The lines are really those 
standard or conventional framework, 
illustrations of this book when skulls 
When the left half is completed, 
the right half is then undertaken, as shown in fig. 126. 
The right half of the skull is built up on a similar 
framework of lines, the parietal fragment being placed 
so that it corresponds in all points with the panetal in 
the side already built up. If our reconstruction is right, 
then, when the right and left halves are brought together, 
to form the complete roof of a skull, all the corresponding 
points of the two sides should fall into corresponding 
positions. If the two sides are found to agree, we may 
