1 2 Proceedings of Royal Society of Edinburgh. [sess. 
the line joining the centre of this opening on one side of 
the head to the same point on the other) and the bridge of the 
nose, and the central point of the upper jaw between the two 
central incisor teeth, respectively, the upper lip being lifted out 
of the way in the latter measurement. The index calculated from 
these two measurements appeared to make the people far more prog- 
nathic than I would have expected, if the centre of the auricular 
orifice, as has often been assumed, corresponded, as far as the measure- 
ments from which the gnathic and vertical indices are calculated are 
D 
Fig. 2. — Diagram illustrating the relation of measurements taken from the 
basion to those taken from the auricular point. A = basion. B = auricular 
point. C = nasion. D — alveolar point. 
concerned, in some degree with the basion ; and, at Professor 
Cunningham’s suggestion, I commenced a series of measurement on 
skulls in the Anatomical Museum of the University of Edinburgh, 
in order to see how far this assumption was legitimate. Before I 
had gone far in this investigation — indeed, on the same morning on 
which it was commenced — the solution of the problem became 
obvious, with the result that I find that the two points do not 
correspond with one another, for the following reasons, which are 
made clear by the diagram (fig. 2). In every skull examined I 
discovered that while the centre of the auricular orifice was several 
millimetres higher than the basion, it was also several millimetres 
posterior to it, so that while the auriculo-nasal length and the basi- 
