Theory of Chance to Racial Differentiation. 



113 



which there appears to be a sensible difference between male 

 and female in this matter. From some statistics with which 

 M. Manouvrier kindly furnished me, there appears to be 

 a difference of some 1*5 units in the cephalic index of male 

 and female Parisians, and this whether the material be 

 drawn from the West End or the City *. I have the data for 

 upward of 1000 French skulls obtained from the Paris 

 Catacombs, and measured by MM. Broca and Manouvrieiv 

 I owe to the courtesy of the latter distinguished anthropo- 

 logist a transcript of the measurements and sexing from the 

 liegistres Crdniometrigues of the Laboratoire d'Anthropo- 

 logie at Paris. So far as the cephalic index was concerned, 

 we obtained the folio wing results : — 



If the sexing here be correct, there can be no* doubt 

 that there is differentiation in cephalic index between the^e 

 men and women. Turning to the variability, there is a 

 difference in the standard deviations of '231, and the probable 

 error of this difference =*143. Thus variability seems also, 

 if less certainly, a sexual character. We have accordingly a 

 mass of material which, if the craniclogist be right, consists 

 of two fairly marked groups. Plotted as a curve f (fig. 1) 

 (p. 114) it has a distinct skewness. Is this due to the mixture 

 of sexes ? If it be, can it be possible that only some 28 per cent. 

 of the women's skulls have survived, as against 72 per cent, 

 of the men's J ? 



Clubbing male and female skulls together, I handed the 

 material to Miss C. D. Fawcett, B.Sc., and asked her to 

 mathematically investigate the possibility of resolving it into 

 two Laplacian distributions. Her results were afterwards 

 verified by Dr. W. 11. Macdonnell. His constants, based 

 upon Mr. W. F. Sheppard's improved expressions for the 



* l The Chances of Death,' vol. i. p. 352. 



t I have to heartily thank Mr. K. Tressler for preparing the 

 diagrams. 



X There is generally a preponderance of male skulls in sexing, owing 

 to their greater strength enabling them to survive batter ; hut I have never 

 before come across such an immense disproportion as in the Catacombs. 



Phil. Mag. S. 6. Vol. 1. No. 1. Jan. 1901. I 



