DAVID HEPBURN. [No. 2. 



paring the ratio of basi-nasal diameter to basal-transverse 

 diameter, I find that it was 



1 to 1.12 Australian Aboriginals (dolicho-cephalic); 



1 to 1.18 Sandwich Islanders (brachy-cephalic); 



1 to 1.19 Scandinavians (dolicho-cephalic); 



1 to 1.25 Scandinavians (meso-cephalic); 



1 to 1.3 Scandinavians (brachy-cephalic). 



Thus in each class of the civilised skulls there was a 

 proportionately greater basal-transverse diameter. By refe- 

 rence to Table V, it will be seen that as the basi-nasal 

 diameter diminished in length, the basal-transverse diameter 

 increased, and this increase is evidently required for the 

 accommodation of the growing cerebrum. 



The difference between the ratios of the savage dolicho- 

 cephalic and brachy-cephalic skulls was 0.06, whereas 

 between the civilised dolicho-cephalic and brachy-cephalic 

 skulls the difference was 0.11. There was also a greater 

 difference between the ratios of the civilised and savage 

 dolicho-cephalic skulls, than between savage dolicho-cephalic 

 and savage brachy-cephalic skulls. The figures tabulated 

 also show that alongside of the reduction in the average 

 amount of the basi-nasal diameter, there is an immediate 

 increase in the average amount of the basal-transverse 

 diameter. 



A complete explanation of these facts is no doubt difficult 

 to find, but the reduction of the basi-nasal diameter may fairly 

 be attributed to changes in the characters and proportions of 

 the facial bones, dependent upon altered habits resulting from 

 changes in the staple food supply. Under suitable conditions 

 we can readily imagine the flerce, flesh-tearing, prognathous 

 savage losing much of his need for prognathous jaws in a 

 climate where grains and vegetable food formed his chief means 

 of subsistence. With the shortening of the basi-nasal segment 

 of the cranial floor, the growing cerebrum would require addi- 

 tional width for its accommodation, and thus the basal-transverse 



