250 



THE AMERICAN NATURALIST [Vol. XL VI 



The matter is directly pertinent to the present discus- 

 sion because "long heads" and "broad heads" are con- 

 tinuously crossing and we know what the direct and ulti- 

 mate effects of such crosses are. The evidence has im- 

 portant bearing also on the influence of selection, environ- 

 ment, and inheritance or the effects of use and disuse. 



Determination of the proportions of the cranium or 

 the cephalic index is one of the standard tests or race; 

 it is an expression of the greatest breadth of the head 

 above the ears and the percentage of its greatest length 

 from the forehead (glabella) to back, the latter measure- 

 ment being taken as 100. Three types adopted by anthro- 

 pologists are: 



Braehycephalic, 80.1 and above 100-80 



Mesocephalic, 75.1-80 80-75 



Dolichocephalic, 75 and beloAV 75-62 



Among the present races of Europe the widest limits 

 of variation between brachycephaly and dolichocephaly 

 are in the averages between 73 and 87; individual ex- 

 tremes of 62 and 100 have, however, been observed. 

 These extremes in European head form do not coincide 

 either with geographic or political boundaries, but are 

 attributed to the entrance into Europe of braehycephalic 

 and dolichocephalic types which evolved in Asia. Simi- 

 larly among the aborigines in America the indices range 

 from a low dolichocephaly as among the Delaware, Pima 

 Indians, etc., to a decided brachycephaly as among the 

 Athabascan tribes in Panama, Peru, and other localities. 

 A significant fact in Europe is that dolichocephaly and 

 brachycephaly are extremely stable characteristics in 

 heredity. The significant fact in America is that through 

 a very long period of time the various races of Indians, 

 who are believed to have had originally a similar origin, 

 have acquired under conditions of geographic isolation 

 considerable diversity in the proportions of the head. 

 Similarly A. Keith 32 from the present distribution of the 



"Keith, A., Journ. Eoyal Anthropological Institute, 1911. See Nature, 

 Vol. 88, No. 2195, November 23, 1911, p. 119. 



