56 (248) THE VERY HIGH AND VERY LOW INDICES. 
For the low indices the increasing of the headlength for men is 20.11 
— 19.34 = 0.77 cM., for women 19.01 — 18.36 — 0.65 cM. The decreas- 
ing of the headbreadth is for men 15.4 — 14.76 — 0.64 cM. and for 
women 14.8 — 14.13 = 0.67 cM.-With this limited material of low in- 
dices, for men the increasing of length is somewhat larger than the de- 
creasing of the breadth (0.77 — 0.64) ; for women (44 casesonly)increas- 
ing and decreasing are almost equal (0.75 — 0.67). For low indices 
among men the heads are therefore relatively somewhat more long than 
narrow. 
The variability of the headlength is here also larger than that of the 
breadth, both for men and women. 
In our limited material for men the variability of the length as well 
as of the breadth is larger than that of the intermediate length and 
breadth of the whole material. For women these numbers are smaller 
than those of the average value. 
So the headdimensions of dohchocephalic men (index 75 and lower) 
have a very large variability. 
The sum of headlength and headbreadth which gives some indic- 
ation of the headsize (1920 b,) is for men for high indices 34.67 cM, 
for the indices of the whole material 34.74 cM and for low indices 
34.87 cM. For women these numbers are 33.01, 33.16 and 33.14 cM. So 
there are slight differences: the heads with high indices are upon an aver- 
age somewhat smaller than those with low indices. 
The number of men with high indices is in our material smaller than. 
that of women; the proportion is 0.71. For the whole material the pro- 
portion of men and women is 0.65. So there are among the very high 
indices relatively no more women than men. Among the low indices are 
much more men than women (cf. 1920b). 
So the calculation of the variability and the construction of the 
curves of variability do not make it clear that there are twotypesof bra- 
chycephalic heads the large one and the small one, no more than we 
have found it, when elaborating the total material: (1920b table, 
curves). Yet it is important that we find the average size of the head 
with the high brachycephalic index somewhat smaller than for the 
whole material. So among the heads with high indices there are move 
small ones than among the whole material. 
When looking over table X, where the families just as those of the 
tables I, II, III and other ones have been classified according to the 
