hrducka] 



PHYSIOLOGICAL AND MEDICAL OBSEEVATIONS 



117 



The increase of the length of the head continues, it is seen, without 

 much irregularity throughout childhood and adolescence. The most 

 pronounced augmentation occurs in the males between the period of 

 later adolescence and that of adult age; this change is undoubtedly 

 due to the development of the region of the frontal sinuses and the 

 glabella. 



In the Pima of both sexes and of all the stature groups the antero- 

 posterior diameter of the head is longer than in the Apache, but this 

 is a result of a difference in shaj^e of the head and not in its size as a 

 whole. 



In the males the length of the head at nearly every stage is a little 

 greater than in the females of the same stature. The difference is 

 quite uniform during childhood and earlier adolescence, but becomes 

 more marked at the completion of growth, owing in the case of the 

 adult males to excess of development in the region of the frontal 

 sinuses. 



Data bearing on the subject, arranged by stature groups, is here 

 set forth: 



Diameter lateral maximum 



The maximum horizontal breadth of the head follows the growth 

 of the body somewhat less regularly than does the length. There is, 

 apparently, but little advance in this dimension in the lower stature 

 groups, the main increase taking place after the children have reached 

 the height of 150 cm. This condition may be observed in all the 

 divisions. 



As to cUfferences between the two tribes, the conditions are the 

 reverse of what they are with respect to the length of the head. As 

 to sex, in males the breadth of the head, like its length, is at nearly 

 every point in growth a little greater than in the females of the same 

 height. In both the tribes dealt wdth in this paper the differences are 

 least in the case of cliildren ransino; from 140 to 150 cm. in stature. 



