128 
DK. J. CLELAND ON THE VAEIATIONS OE THE HUMAN SIvULL. 
curving rapidly forwards, and consider the incisura of the frontal bone as being mor- 
phologicaly its distal extremity, then the angle mentioned indicates approximately the 
amount of curve which exists. When the foramino-basilar and orbito-basilar angles are 
equal, the foramen magnum and the orbital length lie at an angle of 180°, or, in other 
words, are parallel. According as the orbito-basilar angle is greater or less than the 
foramino-basilar, the cranial curve is less or greater than 180°. 
The foramino-basilar and orbito-basilar angle and the cranial curve require to be all 
considered together ; and this is more particularly the case, since it is a remarkable fact 
that, while the foramino-basilar and orbito-basilar angles have a wide range of variation, 
the adult cranial curve varies within much more restricted limits ; or in other words, 
the difference between the foramino-basilar and orbito-basilar angles in any skull being 
limited, these angles are to a considerable extent interdependent. Thus in the Kafir 
skull G8, the foramino-basilar angle measures 128°, and in the female Kafir it is 150°; 
the orbito-basilar angle of the skull of the Hottentot measures 129°, and that of the 
Greek skull 46 measures 150°; but a cranial curve 21° more' or less than 180° is pro- 
bably never to be met with in any undeformed skull. One female French skull, 25, 
has a foramino-basilar angle of 162°, while another, 26, has an orbito-basilar angle of 
128° ; but these two angles could not coexist in any skull except with very great defor- 
mity ; were they to do so they would give a cranial curve of 214°; and the only skull 
in which so great a curve is approached is 91, the skull with the base driven in, in which 
the curve is 212°. 
While in adult European skulls the cranial curve seldom falls short of 180° by more 
than three or four degrees, and more frequently exceeds that amount, in the six fcetal 
skulls examined it varies from 150° to 176°. As, however, those in which the amount 
of curve is lowest are skulls of foetuses of the 4th, 7th, and 8 th month, while the highest 
amounts occur in a foetus of the 5th and another of the 8th month, it would appear that 
the increase of curve proceeds more rapidly in one skull than in another. A smaller 
degree of the same irregularity is seen on comparing the five skulls of new-born infants; 
these seem, however, clearly to show that the cranial curve is not quite completed at 
birth, while an examination of the skulls of older children shows that at least in some 
instances it is completed before the third year. 
Males. 
Females. 
Number’ 
measured. 
Foramino- 
basilar angle. 
Orbito-basilar 
angle. 
Cranial curve. 
Number 
measured. 
Foramino- 
basilar angle. 
Orbito-basilar 
angle. 
Cranial curve. 
Kafir 
3 
133| 
144 
I69f 
1 
150 
144 
• 
OO 
CT5d 
Esquimaux... 
2 
1321 
1 4 1 A 
171 
Negro 
5 
136 
139 
177 
2 
137 
138 
179 
Kanaka 
1 
129 
132 
177 
1 
138 
129 
189 
Greek 
5 
138 
140y 
1774 
Hindoo 
3 
128 
1274- 
180 
Australian ... 
2 
139| 
138! 
181 
French 
6 
1 41-| 
139f 
18lf 
3 
145| 
138 
1871 
Scotch 
5 
13511 
1 331- 
1821 
2 
1394 
1364 
183 
Irish 
6 
143| 
139 
184V 
3 
1474 
140 
1874 
German 
5 
!46f- 
1391 
is 74 
3 
146 
1411 
184f 
