W. R. Macdonell 
91 
Accepting this view would only mean somewhat greater scatter in time round 
about the same mean date, and we may consider ourselves fortunate, in most cases 
of large cranial finds, if it is possible to fix the date of the bulk of the material 
with anything like certainty within a hundred years. 
(3) Measurements and Methods of Measurement. 
All the detailed measurements given in my former paper are given here except 
Oi, the length of the palate from the base of the spi)ia nasalis posterior, and 
the same symbols and methods of measurement were adopted as before. There 
were no mandibles in the collection. 
Certain additional characters are given, viz. : 
(/) Length from nasion to bregma {S-y). 
(Jc) Length from bregma to lambda (S.,). 
{1') Length from lambda to opisthion (S-^). 
These three were measured with the steel tape. . . 
(/") Length from lambda to opisthion (S^), measured with the callipers. 
S.2, S.j and S-i were frequently difficult to measure on account of difficulty in deter- 
mining the lambda precisely. 
(x) Greatest length of foramen magnum ( fml). 
(y) Greatest breadth ol foramen magnum (fmb). 
(v) Foiaminal Index (lOO'~^^\ 
\ fmlj 
(tt) Ratio of radius of curvature of the cerebellum (from lambda to opisthion) 
s I ^ 
to S3' (CC); this measure of cerebellar curvature equals ^f4/y 94 (g/ 9/) ^'^^T 
nearly*, and will be termed the Cerebellar Index. 
The Cerebellar Index, which measures the convexity towards the inion, seems 
useful as giving some indication of the capacity of the cerebellum. A low 
Cerebellar Index is a sign of large convexity. The Cerebellar Index of men is lower 
and less variable than that of women, to judge from the first investigation of it 
now made in this paper. 
I have to thank Dr Alice Lee for help in calculating this ratio. I am also 
greatly indebted to Miss Winifred Gibson for the foraminal measurements and 
also for calculating the angles A, N, and B on the trigonometer. 
* Bertrand, Calc. Diff. p. 552. 
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