M. L. TiLDESLEY 
253 
c 
P-i 
Table for oblaining Tetrachoric r. 
Greater Frontal Prominence 
Right and 
equal 
Left 
Totals 
Right and equal 
17 
21 
38 
Left 
87 
16 
103 
Totals 
104 
37 
141 
'o a 
O.S 
Contingency Table. 
Greater Frontal Prominence 
Right 
Equal 
Left 
Totals 
Right 
3 
14 
21 
38 
Equal 
3 
20 
11 
34 
Left 
35 
29 
5 
69 
Totals 
41 
63 
37 
141 
The mean value of Cg (uncorrected) in 3 x 3 tables of samples of this size 
drawn from a population where there is no contingency will be '1661 ± -0568. 
The value of C'g obtained may be taken as significant as compared with this, and 
that of r is distinctly so. We can therefore conclude, on the basis of our material, 
that these two forms of asymmetry do tend to be associated together, though the 
association is by no means perfect. 
A feature that has been frequently noted in the Cranial "Remarks" of previous 
workers, is the existence of a depression slightly above the region of the pterion, 
called the Sylvian depression. Noticing the frequency with which this occurred on 
one side only, or on one side more markedly than the other, it occurred to me to 
subject this depression to the same investigation as was applied to the occipital 
and frontal bones. For this purpose I have not concerned myself with the depth of 
the depression, but merely with the question whether it was equally represented 
(or equally unrepresented) on both sides. One hundred and thirty of my skulls 
were undamaged in that region and available for data. They gave the following 
results : 
Sylvian depression greater on R in 90 skulls. 
equal R and L in 33 ,, 
„ „ greater on L in 7 ,, 
In my series, therefore, there is a considerable preponderance in favour of the 
right side. 
