614 Proceedings of Royal Society of Edinburgh. [sess. 
(a) Brachycephali . — Only one skull gave similar prse-auditory 
and prse-condyloid segments. In three, the centre of the meatus 
was anterior to the plane of the condyles ; and in the remaining 
seven, the centre of the meatus was behind the plane of the 
anterior borders of the condyles by distances which varied from 
2—12 mm., the average for the seven being 4*2 mm. 
(b) Dolichocephali . — In one skull the prse-auditory and prae- 
condyloid segments were alike. In two skulls the centre of the 
meatus was 2 mm. in front of the plane of the condyles ; in the 
remaining nine the centre of the meatus was behind the plane of 
the condylar anterior margin by distances which varied from 1-6 
mm., the average being 3 - 7 mm. 
(c) Anthropoids . — In the four anthropoids that were measured 
the centre of the meatus was in each case definitely in front of the 
plane of the condyles by distances which varied from 8-15 mm., 
the average for the four being 10 mm. 
These measurements indicate, that relatively the external 
auditory meatus is farthest forward upon the glabello-occipital 
length in anthropoids, and that it is farthest hack upon the same 
diameter in brachy cephalic skulls. Further, it would appear that 
during the acquisition of the erect attitude, as the occipital 
condyles have apparently moved forwards in relation to the 
glabello-occipital length, so the external auditory meatus has 
moved backwards until in the majority of skulls the centre of the 
meatus really falls behind the plane of the condylar anterior 
borders. 
Of course this is a small number of measurements on which to 
base any broad generalisation, and such an attempt is not intended. 
The object has been to illustrate the kind of information which is 
within reach by means of a particular instrument, an extended 
application of which may. evolve additional new facts. At the 
same time I cannot refrain from mentioning, in conclusion, that it 
seems more than a coincidence to observe, that, in every particular 
where an average total or an average percentage has been possible, 
the dolichocephalic skulls have been placed nearer to the anthro- 
poids than in the case of the brachycephalic skulls. 
