DE. J. CLELAND ON THE VARIATIONS OE THE HUMAN SKULL. 
119 
by placing — before the figure. Thus the following formula is sufficient for the com 
struction of a diagram of the Irish skull 54: — 
O 
-•4 --7 -1 --65 -1-2 --6 --3 -75 1 9 4-4 5- 3-85 1-8 1-3 14 
•05 — T35 1'05 T9 3o 3'65 — 3 - — 3'65 — 3 - 65 —23 '55 3'05 3’65 3’55 1-5' 
If to this formula there be added the breadth at as many points as may be desired, and 
the positions of those points, the utmost completeness may be given to it. By this 
system of notation the outline of the profile of every skull in every Museum might be 
recorded with the greatest accuracy, either from measurements taken with the cranio- 
meter described, or from geometrical drawings, or tracings of vertical sections. 
Close to the upper and posterior margin of the external auditory meatus there is in 
almost every skull a slight pit, which may be termed the postauricular depression, left 
between the margin of the meatus and the main part of the pars squamosa. This pit, 
from its minute size and its centrical and constant position, is well fitted for receiving 
the points of the screws by which the skull is kept in the craniometer, and for being 
the starting-point from which the horizontal and vertical distance of other parts may be 
computed ; and even when the screws have to be fixed to some other part, as happens 
occasionally when the pits are ill marked, it is easy to correct the record of measure- 
ments so as to calculate the distances from the usual place. In making the craniometric 
measurements on which this communication is founded, the skull in each instance was 
first placed in the frame with the base upwards, and, while so fixed, the position was 
taken of the fore and hinder limit of the foramen magnum, the occipital tuberosity and 
the point midway between the tuberosity and upper angle of the occipital bone which 
is distinguished as the midoccipital point, also the spheno-occipital suture, the posterior 
limit of the hard palate in the middle line, the lowest point of the alveolar process 
between the middle incisors and the tip of the nasal spine. The skull was then turned 
round and fixed with the arch upwards, the sliding screws being replaced to support it 
at exactly the same level as when it was reversed. The positions of the midoccipital 
point and nasal spine were again taken, to secure against error from strain, and the 
accurate adjustment of the skull having been thus tested, one could proceed to take the 
position of the upper angle of the occipital bone, the middle point of the sagittal suture, 
its anterior extremity, the fronto-nasal suture, the point on the frontal bone midway 
between these two last points, and also the most prominent point of the glabella. 
Sometimes the exact point which was to be considered as the one wanted for measure- 
ment had to be determined a little arbitrarily, but this did not occur to any great extent. 
Thus a difficulty of more than a line would often occur as to the exact point to be marked 
as occipital tuberosity ; in infants a point in the anterior fontanelle had to be chosen as 
representing the junction of the frontal and parietal bones in the middle line ; and often 
a difficulty would occur at the upper angle of the occipital bone from the presence of an 
os triquetrum ; but this was usually solved by taking the point at which the limbs of 
the lambdoidal suture would have met had they passed up uninterruptedly. With regard 
to the spheno-occipital suture, while in young subjects the anterior margin of the 
E 2 
