62 Proceedings of the Royal Physical Society. 



of the fact that the eye can see distinct ridges corresponding 

 to the attachments of the abnormal muscles, yet neither the 

 diameters nor the popliteal index which is calculated from 

 them appear to have been materially affected. This seems 

 all the more remarkable since those sections of the shaft 

 where the platymeric and pilastric indices are calculated are 

 considered to be definitely affected by the action of the 

 muscles attached to them. 



In the femora under consideration both popliteal indices 

 are comparatively low, in fact they are among the lowest 

 which I have been able to record (3) from modern British 

 female femora, in which my recorded average popliteal 

 index is 78-25. My recorded average for both sexes is 

 78*1, with a range of variation from 66 to 8 9 '7. It is true 

 that the femur in which the muscles were most markedly 

 abnormal presents the higher index, but I do not attach 

 much value to this slight difference, for among many femora 

 taken from many diverse races of mankind I have only 

 found one male Lapp, one male Bushman, and one female 

 Eskimo, in whom the two femora yielded the same index. 

 Among the very few anthropoid apes which I have had the 

 opportunity of examining (3), the two femora of the same 

 individual gave a similar index in the case of one orang- 

 outan and two chimpanzees. 



It seems to me, therefore, that we cannot attribute great 

 modifications of the femoral diameters in the popliteal 

 reoion to the results of muscular attachments. It is difficult 

 to imagine that any of the muscles attached to the femur in 

 the popliteal region could ever attain such proportions as 

 would account for the high popliteal indices of many femora. 

 In one femur of an Australian aboriginal, I have recorded (3) 

 a popliteal index of 96*9, a figure which indicates that the 

 shaft was almost cylindrical in the popliteal region. This 

 same very high index (96-9), with the associated convexity 

 of the popliteal surface of the femur, formed one of the most 

 striking features of the famous Trinil femur, and its dis- 

 coverer, Dr Dubois, acting on my suggestion (7), felt inclined 

 to credit the condition to a series of muscular attachments, 

 which might have carried the characters of the pilastric 



