130 
A Study of the Crania of the Morion 
The occipital indices so far obtained are : 
Male 
Female 
English (Moorfields) 
Moriori ... 
Gaboon, Bantus 
Congo, Batetelus 
58-5 
62-2 
68-3 
68-8. 
68-5 
59-2 
64-2 
69-2 1^ 
67-Oj 
68-1 
The smaller the index the smaller is the radius of curvature of the occipital 
arc in relation to its chord, i.e. the occipital is more rounded. The order shows 
that the English have most, the Negro least occipital development, and that 
the Moriori male stands nearer to the European than to the Negro. 
The Frontal Index is on another footing. If the nasio-bregmatic chord and 
arc be given, i.e. S'l and S^, then 
gives the frontal index in the form of the ratio of the radius of curvature of the 
frontal arc to the frontal chord. To obtain this index the distance from nasion 
to bregma along the chord should be measured with the callipers. Not having 
measured this, I took the values from the contours which should be extremely close 
to the measured values as the terminals are very definite points. The results were : 
If now we wish to replace the index by if = 100 X subtense/chord, we must 
deduce ^^ from 
There resulted the values 21-6 and 21-9 to compare with the direct contour values 
of if, 19-4 and 21-1. The reason for the excess is clear: it is due to the exaggera- 
tion of the length of the frontal arc (treated as a circular arc) owing to the 
massive glabella, more divergent in the case of the male than the female*. On 
the other hand if we take English males, we find from arc and chord measurements 
of the frontal 7/= 70-1 leading to if= 21-0, which is in closer accord with 22-2, 
the direct value of the subtense to chord index, thus indicating that with less 
glabellar prominence, the results of the two methods would be more nearly equal 
and would more closely justify the assumption of the approximate circularity of 
the frontal arc|. On the whole if the frontal curvature is to be determined by 
direct measurement, i.e. not by contour drawing, it will be desirable to adopt a 
modified form of Merejkowsky's simometer J. It would not be hard to devise, but 
it would have to be considerably larger, and the subtense would have to be 
obtained by contact — it would not necessarily be at the bisector of the chord. 
* Had we supposed the arc to be catenary rather than circular the values (see Tables for Bio- 
metricians and Statisticians, p. 64) would have been 22-7 and 23-1, still more divergent. A parabohc 
arc was found to be even less successful. 
f Tasmanian aborigines (Berry and Robertson, R. S. Edin. Proc. Vol. xxxi. Table p. 60) give for 
combined sexes, from //(64'91). i/=22'33. 
{ Biometrika, Vol. viii. p. 317. 
Males, 68-7; Females, 67-9. 
