Eveline Y. Thomson 
125 
details. After all the values have been averaged, some error is almost invariably 
introduced in plotting, especially as the contours have to be somewhat thickened 
up for the engraver; thus readings should be made to the middle of the contour 
boundary. But even then with the greatest care the engraver seems to find it 
difficult to reproduce to exactly the same size; however strict the injunctions 
may be we rarely find the engraver's final result to agree absolutely with the 
plotted contour. There may indeed be as much as a millimetre difference. In 
deducing new indices therefore it is well to read off the diagrams, disregarding 
the numbers placed upon them and take the ratio of lengths thus read. We will 
now turn to the type contours. Let us consider first the glabella-occipital length. 
We ought to be able to get this exactly from the sagittal mean sections, and 
approximately from the horizontal sections. There results by measurement: 
Mean glabella-occipital Length L. 
Males 
Females 
No. 
Value 
No. 
Value 
Direct Measurement 
35 
186-9 
22 
178-6 
From Sagittal Contour ... 
33 
186-5 
21 
178-3 
From Horizontal Contour 
33 
185-4 
21 
177-3 
That the horizontal contour does not give the same result as the sagittal is to 
be anticipated, for the horizontal line through the glabella does not necessarily 
pass through the exact occipital point, but the measurement on the sagittal section 
should theoretically agree with direct measurement. Is the slight difference due 
in this case to the fact that one or two skulls could not be used for type contours ? 
Unfortunately the type crania in the earlier cases were not finished so fully in the 
occipital region as the present samples, but I give the following examples : 
Mean glabella-occipital Length L for Males. 
Kace. . . 
English 
Eo-vptian.XXVI 
-XXX Dyn. 
Congo, Batetelu 
Gaboon, Bantu 
No. 
Value 
No. 
Value 
No. 
Value 
No. 
Value 
Direct Measurement 
137 
186-9 
100* 
184-1 
50 
177-8 
50 
179-5 
From Sagittal Contour ... 
100 
186-8 
100 
184-4 
41 
178-4 
50 
177-9 
From Horizontal Contour 
100 
185-9 
100 
183-5 
41 
177-5 
50 
177-6 
* The 100 cJ crania to which direct measurement was applied were not absolutely the same as the 
100 selected for contouring. Fawcett gives 185-1, Maclver 184-5 for prehistoric Egyptians. 
