364 



DR MATTHEW YOUNG. 



This relationship may be expressed in the form of a table as follows 



Table XIX. 



( iroup. 



Occip. > Frontal. 



Occip. > Parietal. 



Frontal > Parietal. 



Female (100) 



Turner 



"K "series (100). 



8 per cent. ( = 1 per cent.) 

 3 „ (=2 „ ) 



20 per cent. ( = 4 per cent.) 

 18-8 „ 



23 „ ( = 2 „ ) 



70 per cent. ( = 5 per cent.) 

 61 „ ( = 4-4 „ ) 

 67 „ ( = 8 „ ) 



From an analysis of the above table it is easily seen that, comparing the male 

 series of 100 with the female series, the numbers expressing the frequency of a definite 

 relationship of the arcs in length to one another are closely similar, whereas the 

 percentages for the three classes in Turner's series (including both male and female) 

 are not markedly different from the male and female groups of the series under ex- 

 amination. The individual variation in the proportional length of the different 

 regions is very considerable, as will be shown when we consider the variability of 

 the segments of the sagittal arc ; and the above table seems to be confirmatory of 

 Cleland's view that it would be " unsafe to deduce any definite relationship between 

 the variation in relative lengths of the arcs and the sex of the skull." Cleland (15) 

 also says with regard to the relative values of these segments of the sagittal arc that 

 national variation is slight, while Schwerz (18) says that " studies on the proportions 

 of the different bones of the vault to one another have shown that we possess in these 

 characteristics a useful means of help for the pursuit of racial research " — a view 

 somewhat different from that of Cleland. 



It has been asserted that the proportion which the parietal segment bears to the 

 occipital and frontal segments of the sagittal arc varies, not only during development, 

 but also to a marked degree in the two sexes. It is stated that the examination of a 

 large number of female skulls goes to show that there exists a lower proportion of 

 both occipital and frontal arcs compared with the parietal in the female skull than in 

 the male. Huschke, quoted by Cleland, states that " in the female, the capacity of 

 both the frontal and the occipital segment is smaller in proportion to the parietal than 

 in the male," while Weisbach speaks of the small forehead of the German female. 



For 100 male and 100 female skulls of this series we get the following mean 

 values : — 





Frontal Arc. 



Parietal 



Arc. 



Occipital Arc. 



Males 



1 33'49 mm. 



127'91 



mm. 



12078 mm. 



Females . 



126*9 „ 



12T4 



?) 



11476 „ 



1 n t,h p m a 1 p 



frontal arc _ 

 parietal arc 



T043 





occipital arc _ .„ 





parietal arc 



In the female . 



frontal arc _ 

 parietal arc 



1'045 





occipital arc _ . ( 

 parietal arc 



