510 FRETS, THE INDEX CEPHALICUS: 
material of Zeeland is not homogeneous (it contains f. i. a. family 
of Vlissingen, tab. C, fam 7la with a rather low index). 








Table 13. Headindex. 
N NTS OF = Ë 
A - 
nt UE Number Index Number Index 
élan dE nen. teri res 45 81.11 61 82.34 
Islands of Z.-Holland. . . . 137 81.03 206 81.55 
Rotterdam. ERP CEC 135 79 2 178 80.32 
Z.-Beveland (Bolk 1908). . . 165 80.7 
Rotterdam (idem) . . . . . 129 78.2 
Summary. 
1. The variability of the headindex with man is larger than with 
woman. 
2. The index of the male is lower than of the female (resp. 80.4 
and 81.04); of brothers lower than of sisters. 
3. Among the low indices there are more males than females. 
Among the high indices there are more females than males. 
4. The headlength of adult men is about 1 cm larger than of 
adult women (resp. 193,4 and 183,6mm). For the headbreadth 
the difference is 6 mm (resp. 154 and 148 mm). 
5. The variability of headlength and headbreadth is larger for the 
male than for the female. 
6. With men and women the standarddeviation of headlength is 
larger than of headbreadth. The coefficient of variation of 
headlength is somewhat smaller than of headbreadth. 
7. Probably the skew curve of frequency of distribution for the 
index fits better this and the Swedish large material than the 
normal curve does (in accordance with TOCHER). 
8. The variability of the index of the Swedish material of 45000 
recruits of RETZIUS and Fürst is a little larger than of my Dutch 
material of adult men (resp. 3.08 and 2.985). 
9. With advancing age the index slightly falls with about one 
unit. The growth of the head continues to about the 25th year. 
10. The amount with which the headindex has to be diminished to get 
the skullindex is very variable and does not exceed 1.5 units. 
fe: 
1 
N # | 

