M. L. TiLDESLEY 
213 
of the board would not affect the nasion, but might have a slight effect on the 
position of the alveolar point, shortening the line slightly in gome cases. 
Burmese Mean Nasio-Basion Length, LB. 
Types: 
Males 
Females 
A 
B 
C 
A 
B 
94-7 (17) 
93-3 (17) 
(J 
Direct measurements 
From sagittal contours 
98-5 (43) 
97-4 (43) 
98-8 (8) 
98-0 (7) 
100-5 (7) 
100-2 (8) 
93-9 (39) 
93-0 (39) 
95-7 (17) 
94-7 (18) 
In marking the basion, defects in both board and tracer would operate to thrust 
the point about 1 mm. in the direction of the obelion; for the nasion we need only 
allow for the defect in the tracer which would carry the point about -O mm. to- 
wards the occiput. If we consider the angle at which these two directions cut each 
other, the shortening shown of about 1 mm. in the contour measurements seems 
very reasonable. 
Mean Length of Foramen Magnnni, f rnl. 
Types : 
Males 
Females 
A 
B 
C 
A 
B 
C 
Direct measurements 
From sagittal contours 
36-7 (43) 
3(3-8 (42) 
35-4 (8) 
35-1 (8) 
37-3 (8) 
37-1 (8) 
34-7 (39) 
34-7 (39) 
35-1 (10) 
35-3 (10) 
35-1 (18) 
i 
35-1 (18) j 
1 
The contour tracer occupied parallel positions in marking these points, and was 
pointing in the same sense. The defects in board and tracer displace their true 
positions to the same extent and in parallel directions, thus having no effect on 
the distance between them. The correspondence between the two sets of results is 
seen to be remarkably close. 
Burmese Mean Basio-Bregmatic Height, H'. 
Types: 
Males 
Females 
A 
B 
C 
A 
B 
c - 
Direct measurements 
From sagittal contours 
136-8 (43) 
134-1 (43) 
136-6 (7) 
133-6 (7) 
140-1 (8) 
137-5 (8) 
131-4 (.39) 
128-8 (39) 
131-9 (17) 
129-3 (17) 
129-9 (18) 
128-3 (18) 
Biometrika xm 
14 
