40 OBSERVATIONS AND MEASUREMENTS ACADEMY MEMBERS IMem " a xxiii; 



Table 32. — Cephalic index 



Mfembers of the Academy 



Old Americans 



Not old Americans 



Old Americans 



at large (entire 



series) 



Subjects 



Average 



M inimum 



Maximum 



Range of variation in percentage of the average 



a 



cv 



78. 56 



3. 00 

 3. 82 



100 



±0. 20 



73. 



85.4 



15. 78 



±0. 14 



±0. 18 



79. 96 



3. 62 



4. 53 



50 



±0. 35 



71.9 



86.2 



17. 89 



±0. 25 



±0. 13 



727 



1 77. 95 



69.7 



90.9 



DISTRIBUTION 



71.9-72.50 72.51-75 75.01-77.50 77.51-8 



10-82.50 82.51-85 86.10-86.20 



Old Americans (100) 



Not old Americans (50). 



Percent 



13 



6 



Percent 

 24 

 18 



Percent 

 30 

 18 



Percent 



24 

 32 



Percent 



7 



12 



Percent 



2 

 12 



CURRENT CLASSIFICATION 



Subjects 



Dolichocephalic (C. I. up to 75) 



Mesocephalic (C. I. 75.1-80) 



Brachycephalic (C. I. 80.1 and over) 



Members of the Academy 



Old Americans 



100 



Percent 



13 

 53 

 34 



Not old Ameri- 

 cans 



50 



Percent 



8 

 36 

 66 



Old Americans 



at large (entire 



series) 



727 



Percent 

 16.6 

 61. 7 

 21. 7 



i In the 247 laboratory subjects 78.28. 



The above data give much food for reflection. The members of the Academy, of both 

 groups, though especially the not old Americans, differ significantly in cephalic index from the 

 old Americans at large, both the Academy groups showing smaller proportions of the dolicho- 

 cephalic and mesocephalic, and decidedly larger percentages of the brachycephalic. Among the 

 European-born members and those of recent American parentage over one-half, and among the 

 old American members one-third, are brachycephalic, while among the old Americans at large 

 the proportion is only a little over one-fifth. There are plainly some factors in the membership 

 that favor broadheadedness. In the not old Americans the main of these factors is doubtless 

 racial heredity, but this cannot be applied to the members of old American parentage who are of 

 the same extraction as the old Americans at large. It is necessary to conclude that in this group 

 the excess of broader heads is connected with a greater weakening, in this on the whole socially 

 favored class, of those mechanical influences that ordinarily keep the skull from relative broad- 

 ening; and such influences could only be those, it would seem, of the muscles of mastication, 

 particularly the temporal muscles. We have seen, under visual observations, that in the mem- 

 bers of the Academy the whole masticatory apparatus is on the average of submedium develop- 

 ment, which harmonizes with the above deduction. The temporal muscles, aside from the mas- 

 seters, are the principal muscles of mastication. They are attached to the sides of the skull and 

 cover an extensive surface of the frontoparietal region on each side. Their presence, but espe- 

 cially their action, exerts a certain amount of bilateral pressure on the skull and thus constitutes 



