126 
DR. J. CLELAXD OX THE YAEIATIOXS OE THE HUMAN SIvULL. 
but the brachycephalous Americans. But the amount of orbital length in the Austra- 
lian, Negro, and Kafir is not sufficient to account for the great length of base-line of 
these skulls ; the Greek, the Hindoo, and the Irish skulls agree with them in the average 
orbital length, while in these, especially in the Hindoo and Irish, the base-line is much 
shorter. At the same time the orbital length is to be recognized as one element on 
which length of base-line depends ; and examination of the different skulls of each na- 
tion shows that the extent of the orbital length usually varies in harmony with that of 
the base-line. 
The adult skulls in which the orbital length is less than l - 8 are the male and female 
French skulls 23 and 26, the female German 34, and the Chinese 85, all of them well- 
proportioned skulls. The anomalous male French skull 89 cannot be taken into account, 
since in it the shortness of the orbit (1*6} is obviously the direct result of early synostosis 
of the lower part of the coronal suture on each side, and has been compensated for by 
undue height of the cranial arch, the result being a very peculiar deformity. 
In the following skulls the orbital length is above 2T, viz. : — in Burke, in the Greek 48, 
in the male Kanaka, in the Australian 73, and the Negro 62 it measures 2T5; in 
Hindoo 60 and in the Hottentot Chief and the Idiot it measures 2*2 ; and in the 
Carib 88 it reaches the extraordinary depth of 2’4. The list thus contains some of the 
very ugliest skulls examined; and of the nine only three, namely, the Greek, the 
Hindoo, and the aberrant skull of Burke, belong to civilized nations. 
So far, then, as these observations extend, it would appear that shortening of the orbital 
length never occurs as a feature of degraded national type, but that elongated orbital 
length does so occur. Where it does so, the probability is that the elongation is in con- 
nexion rather with development of the frontal sinus or diploe than of the cranial cavity. 
It produces antero-posterior elongation of the nasal fossae in their upper part, which may 
perhaps be favourable for the expansion of the olfactory nerve and production of a keen 
sense of smell. 
For amino-optic line (General Table, column 26). — This line, extending from the 
front of the foramen magnum to the point midway between the foramina optica, and 
thus indicating the middle portion of the base, corresponds, as has been said, pretty closely 
with Mr. Huxley’s “ basicranial axis” which, starting from the same point, passes to the 
junction of the sphenoid and ethmoid bones in the anterior cranial fossa. Probably the 
one line is as well chosen as the other ; and it may be frankly admitted that a line drawn 
to the angle of separation of the middle and anterior cranial fossa? in front of the optic 
commissure might be preferable to either. 
In new-born infants and in children the foramino-optic line is about equal in extent 
to the orbital length, whereas in the adult it usually exceeds it. In the ten-years-old 
skull it is of such length as might possibly be permanent, being of a length not uncom- 
mon in the adult female. The extent of this line in the female is less than in the male, 
the difference between the sexes in this respect being still more distinct than in the ex- 
* Journal of Anatomy and Physiology, November 1866, p. 67. 
