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MEMO111S OF THE NATIONAL ACADEMY OF SCIENCES. 



These groups are believed to be not devoid of significance, and will be made the basis of future 

 comparative study of American races. It has been already found, for instance, that in skulls dug 

 from American mounds, where occipital flattening is often encountered, that total posterior flatten 

 ing (Group A) ix much the rarest form. In 68 mound skulls, with sagittal depression, the groups 

 are distributed as follows : Group A, 7 ; Group B, 51 ; Group C, 10. It may be, too, that our future 

 studies will compel us to establish another class, in which the depression is below the lambda. 



z 6 



FIG. 2fl. Occipital depression. Group A. 



Besides these sagittal variations in depression, we have different forms and degrees of lateral 

 depression, i. e., the depression, instead of having its center on the median line, has it more or less 

 to one side. This character naturally divides itself into two groups right and left. Informing 

 these groups we have depended upon a mere inspection of the skull and not upon measurements, 

 only a- skull which had an obvious lateral deformity being included in either group. 



