428 Variation and Correlation of Skull Measurements 
length of the nasal bone, the female gives relatively greater values than 
the male. Although the excess shown in the female is not large in the 
case of the zyomatic width, and in the case of the height and length of the 
cranium yet the width of the cranium or squamosal distance is decidedly 
greater in the female than in the male, as has already been seen from the 
measurements of the extremes. When mean values for the length of the 
entire skull are reduced to the same standard and the associated measure- 
ments are compared, all the three diameters of the cranium of the female 
are seen to be relatively greater than those of the male in respect to the 
length of the entire skull. The cube root of product of these three 
diameters in the case of the male is 39.01 per cent of the length of the 
entire skull and in the case of the female 39.52 per cent, thus indicating 
that we might expect the relative capacity of the female cranium would 
be sensibly greater than that of the male. This apparent superiority of 
the female cranium over that of the male is not due, however, to the 
relatively greater lengths of the three cranial measurements of the female, 
but is due to the fact that the nasal bone in the male skull is consid- 
erably longer, thus producing a somewhat less percentage value for 
cube root of the product of the three diameters of the male cranium. As 
a matter of fact, when the length of the entire skull is equated either to 
male or to female standard by means of the characteristic equations and 
the resulting measurements of the cranium in the two sexes are compared, 
the size of the cranium in the two sexes is almost identical. We shall dis- 
cuss this point later (page 436). It is therefore enough at the present 
moment to see that the somewhat greater percentage values obtained from 
the three diameters of the cranium, when mean values for the length of 
the entire skull are reduced to 100, indicate that the nasal bone is much 
shorter in the female, and vice versa. 
(b) Relative variability in the two sexes—The relative variability in 
the two sexes is a question which has passed through various phases during 
the last century. The several opinions held by different investigators are 
fully summarized by Havelock Ellis in his book on “ Man and Woman,” 
94. The history of this question may therefore be omitted. It is, how- 
ever, important to note here that the quantitative investigation of this 
question has been made for the most part on the human subject. 
As is shown in Table I, the standard deviation is in every case greater 
in the male than in the female except in the case of the squamosal dis- 
tance. Since the standard deviation measures the amount of concen- 
tration of the variates about the mean, the greater the standard deviation 
the less will be the concentration and consequently the greater will be 
