184 PROCEEDINGS OF THE NATIONAL MUSEUM. vouxxxn. 



lute proportions ^ In this instance the fossae can be advantageous!}' 

 contrasted with the greatest ante ro-posterior(glabello-occipital) cranial 

 diameter, one of the most familiar of skull measurements. 



There are in all 60 skulls (3 series each of 20 specimens) of white 

 males and 30 (3 series each of 10 specimens) of white females. Tak- 

 ing the largest '^ and the 9 smallest (3 of each from each series) of the 

 former and the 6 largest and 6 smallest (2 of each from each series) of 

 the latter group, we find the following conditions as regards the 

 length of the frontal cavities: 



liehitio)!. of llie lengtli of the (interior fossx to tJie greate>^t efternal length of tJie skull, in 

 rrania of extreme sizes, in wldtes. 



Average relation of the mean length of the two anterior fossa> to the 

 greatest external cranial diameter, the latter being taken as 100, in 



the largest skulls 



Extremes 



The same in the smallest skulls 



Extremes 



Males. Females. 



The differences are not large, and the detail data showed individual 

 exceptions to be quite numerous; nevertheless both the average values 

 and the extremes plainly indicate a predominance of relatively longer 

 frontal fossaj in the smallest and of relatively shorter frontal cavities 

 in the largest crania. 



Very mucli the same conditions as in whites were found in this regard 

 also among the Indians and the negroes, namel}^: 



Relation of the length of the anterior fossse to the greatest external length of the skull in 

 crania of extreme sizes in the Indians and negroes. 



Males. Females. 

 Average relation of the mean length of the two anterior fossse to the greatest 

 external cranial diameter in the largest skulls: 



6 Indians (3 of each series) 26. 3 



3 negroes 26. 8 



2 negroes 28. 2 



The same in the smallest skulls: 



6 Indians (3 of each series) , 26.5 



3 negroes 28. 3 



2 negroes 28. 6 



The preceding figures are open to one objection — the external length 

 of the skull, to which lengths of the fossse were compared, includes 

 two walls of bony tissue, and it is not certain that the proportion of 

 the measurement due to this tissue, known to differ in the sexes and 

 races, is the same with the large as well as the small skulk. The 

 larger this proportion of bony substance the smaller must be the 

 relative length of the fossai, and the opposite. It was actually found, 

 by comparing the dorsal with the ventral length, that in most of the 

 series the amount of l)one entering into the composition of the 

 greatest external antero-posterior diameter of the skull is larger in 



« The size of the skull being determined by the mean of its greatest length and 

 breadth ; height was not obtainable in most cases, but there were no extremes. 



