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Cranial Type-Contours 
which he asserts are not represented by numerical estimates, but which form 
essential factors of his appreciation of both sex and race. There seemed a need 
accordingly to construct from the contours average or type contours, which might 
serve as a first stage in the determination of a true type skull. If a skull can be 
found in a given series which agrees practically with the three chief type contours 
in all the details of its three individual contours, then that skull may, till a better 
method is forthcoming, be taken as the racial type. If we remember that the 
parts of the skull without being very highly correlated are sensibly correlated, we 
see at once that the mean skull is not a purely fictitious entity, it will approach 
closely to the actual modal skull characteristic of the biggest class in the com- 
munity. It is the skull possessing the maximum frequency, or corresponds to that 
of the individuals near the apex of the multiple correlation surface. Our object 
therefore should be to obtain from the collection of individual contour tracings 
mean contour tracings, and by comparison with the individual contours to reach 
the type skull. This skull can then be perpetuated by photography, and, if 
accompanied by the mean contour tracings, serves, until a better method is de- 
vised, to represent the type with all those qualitative features on which the 
anatomist lays special stress. The same mean contour tracings will also serve to 
differentiate the subtle differences due to sex and possibly to cross-breeding*. 
(2) Construction, of Type Contours. It remains of course to develop some 
method of obtaining an approach to a mean or type contour from the original 
individual contours. Several methods may be conceived, but after considerable 
thought and some experimental work the following scheme was settled upon 
and found to work effectively in practice. 
The usual three contours are taken : 
(a) The transverse vertical or auricular coronal section. The skull being 
placed on the craniophor and adjusted in the usual manner to the Frankfurt 
horizontal plane j - the horizontal rod of the craniophor determines the "apex" of 
the skull. The plane through the apex of the skull (which is marked with a 
pencil stroke) and the "auricular points" is the transverse vertical plane of the 
skull. The skull being now transferred to the Klaatsch apparatus this vertical 
plane is made horizontal and the contour traced from " auricular point " to 
" auricular point " through the apex. The line joining auricular point to auricular 
point is the " auricular line " of the contour j, and the line perpendicular to it 
* For example, apart from true negroes, a certain number of skulls are put aside as "negroid." Let 
us suppose this collection contoured, reduced to the mean contours and the closest individual to these 
mean contours selected. This individual will then represent the average "negroid" type, and this 
skull can be compared by photography or directly with those of the true negro and of the pure race 
selected in the same manner. 
t See Fawcett and Lee : Biometriha, Vol. I. p. 414. 
X The "auricular line" is the transverse straight line tangential to the upper border of the ear 
openings; it does not correspond to the centre of the auricular passages, but is represented by the 
line at the top of the auricular plugs of the craniophor. Most cephalometers used on the living head, 
not only measure the flesh at the apex, but also measure from the centre of the auricular passages and 
thus give an excess of about 8 or 9 mm. over the true cranial auricular height. 
