NO. 1521. 



MEASUREMENTS OF CRANIAL FOSS.E—HRDLICKA. 



195 



cavities, but the number of cases is not sufficient for any definite 

 conclusion. 



The absolute difference in the length of the two postero-superior 

 fossae is often very pronounced, much more so than in the case of the 

 frontal and middle cavities. It ranged as follows: 



Absolute differences in length of the postcro-snperior foss.r; rigid fossa the longer in cases: 



Adsolute differences in length of the 2iOStero-super%or fossse; right fossa the longer in cases: 



"8 mm. JjI of 8.5 mm.; 1 of 11 mm. 



In 25 subjects, it is seen, the inequality in the length of the two 

 fossae exceeded half a centimeter, and in one it reached 11 millimeters. 



Those figures of the preceding ta])le that concern himian adults can 

 be more conveniently expressed in percentages, thus: 



Posterior superior fosspe longer by — 



0.5 to 2.0 mm., right in 65.5 per cent, left in 30.4 per cent of cases. 

 2.5 to 4.0 mm., right in 17.2 per cent, left in 138.0 per cent of cases. 

 4.5 to 6.0 mm., right in 10.3 per cent, left in 24.0 per cent of cases. 

 Above 6.0 mm., right in 6.9 per cent, left in 7.6 per cent of ca.ses. 



The above brings out clearly a predominance of the minor differ- 

 ences in that category of cases where the right fossa is longer, and of 

 the greater inequalities in the larger class of cases where the left 

 fossa exceeds in length. Similar conditions were noticed with the 

 middle and the anterior cavities; on the side (in both these instances 

 the right) where there was a prevalence of longer fossae, there were 

 also noticed greater actual differences in length from the opposite 

 cavity, and the reverse. 



The inffuences on the length of the two postero-superior fossaj of 

 skull-form, sex, and race are not clearly defined; the question might 

 possibly be settled by much larger series of skulls. 



A comparison of the length of the postero-superior fossae with the 

 combined length of the middle and anterior cavities shows that fre- 

 quently the greater length of one of the former stands in what is in 



