22 DR DAVID HEPBURN ON 
2. Great longitudinal circumference, from glabella to pos- 
terior margin of foramen magnum by tape, plus the length 
of foramen magnum taken by callipers, plus the basi-nasal 
length obtained by callipers. 
3. Transverse circumference, between auricular points. 
across the vertex, plus interauricular length obtained by 
callipers. 
The first of these may be divided into prex-aural and 
post-aural in terms of the auricular point, for the purpose 
of showing whether development has been greater in front 
of or behind the ears. 
The second may be subdivided so as to show how much 
of the circumference pertains to the frontal, parietal, and 
occipital bones respectively. 
The information thus obtained is supplementary to that. 
derived from measurements taken between fixed points by 
means of callipers. As regards the cranium, these are 
measurements of length, breadth, and height. The greatest 
length is glabello-occipital, and this line practically presents 
the length of the cerebrum, subject to deductions, for the 
frontal air-sinuses and the thickness of the skull. 
Breadth is measured at minimum-frontal, stephanie, 
maximum parieto-squamous, and asterionic regions. Of these, 
for ordinary purposes the maximum parieto-squamous is the 
most important, since it is the greatest absolute width of 
the cranium. 
The height is taken between the basi-bregmatic points. 
In themselves these measurements are of great value, 
but their principal interest is found in a comparison of 
one with another. Thus, it is customary to compare the 
length with the greatest width. This is done by assuming 
that the length equals 100, and then representing the 
width as a percentage. The working formula for this. 
calculation is— 
Breadth x 100 
Length 
Thus 
= Cephalic or Length-breadth Index. 
131 x 100 _ 65:5 146 x 100 _ 4.3. 
200 173 
