132 
DE. J. CLELAND ON THE YAEIATIONS OF THE HUMAN SKULL. 
the longest ; then, when the cerebral hemispheres begin to expand, growth passing for- 
wards, the parietal grows so rapidly as to exceed its proportion in the adult, and the 
frontal so rapidly as to attain to the adult proportion : in the latter half of foetal life, 
when the hemispheres push backwards over the cerebellum, growth goes on again more 
rapidly in the back than in the fore parts of the cranium, so that while the parietal 
region maintains its proportional length to the whole arch, the proportion of the occi- 
pital region increases, and that of the frontal diminishes : lastly, after birth, the pro- 
portional length of the occipital region increases slightly, and that of the frontal region 
much more markedly till the adult proportions are attained, which appears to be at a 
variable period within a few years after birth. 
Adult shells . — In the adult skull the individual variation in the proportional length 
of the different regions of the arch is very considerable, and the national variation for the 
most part only slight, while no sexual variation can be safely deduced*. Such national 
variation as exists, however, is of a definite kind. The proportional length of the frontal 
region as compared with the parietal varies pretty nearly pari passu with the propor- 
tional length of the occipital region, or, in other words, the variation in proportion arises 
almost entirely from lengthening and shortening of the parietal region. Thus the 
French and German skulls have both the largest proportion of frontal region and the 
largest proportion of occipital region to parietal ; and more markedly the Chinese and 
Australian skulls have both the frontal and occipital region of considerably smaller 
length as compared with the parietal than is usual. This is the more remarkable in 
the case of the Chinese, since it has been already noted that they have the additional 
childlike peculiarity of shortness of the base as compared with the arch f. 
Length of chord of different portions of the arcli% (General Table, columns 11,12,13, 
14, 15). — In estimating the length of the different regions of the arch, it seemed advi- 
sable to measure not merely the arc of each portion, but likewise its direct length or 
chord ; for it seemed possible that local bulgings and flattenings might produce variations 
* It may indeed be noted that the highest proportions of occipital to frontal are nowhere to be found in the 
list of female skulls measured ; but the writer is inclined to impute this to the uniform absence of that degree 
of muscularity which leads to great prominence of the occipital tuberosity and consequent increase of the sur- 
face length of the occipital hone. It would not be surprising, however, if an examination of a largo number of 
female skulls were to show on the average a diminished proportion of both occipital and frontal arc to the pari- 
etal when compared with male skulls ; such a result would harmonize with Huscuke’s statement, that in the 
female the capacity of both the occipital and the frontal segment is smaller in proportion to the parietal than 
in the male ; and with Weisbach’s account of the low and small forehead of the German female. 
t The measurements of the three portions of the arch in different nations given by Dr. Barnard Davis in 
his ‘ Thesaurus Craniorum,’ the elaborate description of his magnificent collection do not altogether corroborate 
these statements, especially with regard to the Chinese. But the object of the present paper being tentative, 
written as it has been rather in the hope of pointing out explicit methods of comparison than to dogmatize on 
a slender basis with regard to characteristics of particular nations, it has been deemed advisable rather to add 
this caution than to alter the statement in the text. 
J These are the measurements termed by Caiius height of the anterior, middle, and posterior cranial vertebra 
Cards, Grundziige einer neuen Cranioscopie, p. 16. 
