Eveline Y. Thomson 
111 
difference between the two subtenses is 0-2 for the Guanche type contour, a 
difference well within our probable error of determination. If we use the glabella- 
lambda base line very little difference can be made between the maximum and 
bregmatic subtenses, although the maximum subtense now always falls behind the 
bregma, but by something less than 8 mm. As a matter of fact if we set off on the 
contour ^anteriorly and posteriorly to bregma both equal to about 15 mm., then 
the parallel to fl will give a-pproxiaiately NX and the parallel to j3l the glabella- 
lambda line. While these constructions are merely approximate for type contours, 
they will be only very rough for individual crania, yet in default of better rules 
they will give some idea of the position of the A, if only the bregma and either the 
nasion or glabella are known. If we want the actual position of the lambda we 
can only note that the foot of the bregmatic subtense is at an average distance 
•491 of the nasio-lambda line from the nasion, and at an average distance -474 
from the glabella in the glabella-lambda line, but these distances vary much for 
individual races, and a fortiori will vary more for individual crania*. 
Now the point just discussed, i.e. the practical equality of the bregmatic and 
maximum subtenses for both the nasio-lambda and glabella-lambda cases, suggests 
how important it is to 'use a base line which will determine the extent to which 
the vertex of the cranium rises above and recedes behind the bregma. For the 
rising of the parietals above the frontal bone, throwing the vertex far back, is 
one of the marked features of primitive mai^. Whatever may be said against the 
Frankfurt standard horizontal plane — and many of the criticisms arise from 
insufficient experience of its value — it can hardly be disputed that on the average, 
i.e. in type contours, it is a fair approximation to the "horizontal," remembering 
that even for the same individual the "horizontal" is only itself a sort of average 
position. Some plane must be taken to express the marked physiognomic characters 
conveyed by the idea of a retreating vertex and an elevated vertex. This no 
nasio-lambda or glabella-lambda line can accomplish. As far as we can find no 
very definite statement as to how the vertex is to be determined has yet been 
acceptedf. We define the "apex" to be the point of the sagittal suture vertically 
above the auricular line when the skull is adjusted to the standard horizontal position 
on the craniophor. The " vertex " is the highest point of the sagittal or medial plane 
when the skull is in the same position. It is the point of contact of the tangent 
to the sagittal contour drawn parallel to the nasio-gamma line. From this stand- 
point we are able to give quantitative measures to the elevation and recession of 
the vertex relative to the bregma. All we need do is to subtract the indices yjB 
* Thus we attempted to reconstruct the Cro-Magnon skull from a knowledge of glabella and bregma. 
A very poor value of X was found from -474, but an excellent one when the skull was assumed to be 
Guanche. In any such reconstructions it is probably desirable to use any suggestion of racial affinity. 
t See Quain's Anatomy, Vol. iv. Part i. p. 124 (191.5), for example, where the vertex is defined to 
be the "highest point of the arch of the sagittal section." In the diagram, Fig. 104 of this section, 
the nasio-lambda line appears to slope downwards instead of upwards and the "vertex" for this 
position appears to be in front of the bregma. In Fig. 112 the nasio-lambda line is made nearly hori- 
zontal and this adds much to the prognathous physiognomic effect aimed at ! 
