DR. J. CLELAND ON THE VARIATIONS OF THE HUMAN SKULL. 
135 
tions may be to some extent the result of mere individual peculiarities of the few skulls 
examined, but they agree with what is observed with the unassisted eye ; for it is clear 
enough, when attention is attracted to the circumstance, that a foetus eight months old 
has a flatter forehead than a foetus five months old, or a child a few months after birth. 
The skulls of infants present great differences in this respect, but the six skulls of children 
from 2^ to 10 years old, have all got the midfrontal angle of a size which would be 
accounted small in the adult, and therefore indicating a greater curvature than usual. 
As is the case with the frontal region, so also with the parietal and the part of the 
occipital above the tuberosity ; the curve does not go on uniformly increasing or dimi- 
nishing, but at one period of growth is flattened and at another more convex. The 
parietal angle, indicating the curve of the mesial edges of the parietal bones, is as large 
in the three foetuses of the fifth and seventh month as it is in the adult, whereas in the 
foetus of the fourth, and in the two of the eighth month it is remarkably small ; at birth 
it has begun again to enlarge, and in childhood apparently it reaches the condition which 
remains in the adult. On an average the parietal angle is smaller in women than in 
men, the feminine form in this respect resembling that of the young skull. The mid- 
occipital angle, which indicates the curve of the subcutaneous part of the occipital bone, 
is flatter in five of the six foetal skulls than in any of the six infant skulls, and of a size 
very common in the adult, whereas both in infancy and childhood it is of an average 
size much smaller or more prominent than in the adult. It is to be observed, however, 
that the flattening of this part of the skull in the passage from childhood to adult life 
is no doubt due, in part at least, to the laying on of additional substance in the neigh- 
bourhood of the tuberosity. 
In perfect keeping with the changeful development of the curves just mentioned is 
the variation at different ages of the transverse curve of the calvarium between the 
parietal eminences ; for, as is palpable to the most careless observer, that curve rises 
rapidly towards the middle line in the foetus, becomes in childhood remarkably flat, and 
again rises in the middle line as growth proceeds. This will be again referred to. 
Of the remaining angles illustrating the curvature of the arch, the most important to 
be noticed in connexion with the form of the young skull are the fronto-parietal angle 
and the angle of the tuberosity, both of which are decidedly flatter in the infant than in 
the adult. The fronto-parietal angle is also flatter in women than in men. The occi- 
pito-parietal angle is rather more prominent in the infant skull than in the adult. The 
postforaminal angle is very variable, both larger and smaller numbers of degrees occurring 
in the foetuses, infants, and children than in any of the adult averages. The postfora- 
minal angle of the female is on an average smaller than that of the male ; but this is to 
be accounted for by the lighter weight of the female skull, making it less liable to be 
affected by the gravitation changes described in the next paragraph. It may be stated 
generally with regard to the infant skull, that the flatness of the fronto-parietal angle 
and of the tuberosity, and the rapid curvature of the parts of the arch between these 
two angles, together with the great development of the parietal region of the arch, and 
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