48 SMITHSONIAN MTSCKLLANF.OUS COLLECTIONS VOL. 92 



crista aspcra and which in instances may be traced to near the middle 

 of the shaft; tlie meaning of this condition is not as yet understood. 



The mesial border of the fossa constitutes invariably the gluteal 

 ridge or a part of it, and the lateral border is never conspicuous. The 

 size of the fossa may reach very considerable proportions; it has 

 little, if any, relation to the size of the bone. In location the fossa 

 in man is generally postero-lateral, but in some femora it may be 

 dis])laced cldse to, or rarely even into, the lateral border, as is common 

 in the larger anthropoids. Jt has no basic or causative relation to the 

 subtrochanteric llattening of the femur. It is a formation sul generis, 

 not a by-product of any of its neighboring structures. It is allied to 

 other fossae or grooves that serve for muscular insertions and which 

 can be seen to advantage in other — especially the anthropoid — femora ; 

 but the hypotroch.'uiteric fossa in man, as seen at its- optimum in the 

 adolescents, has much more of definitencss and individuality, is much 

 more of a well evolved and differentiated character, than any of the 

 other hollows. 



Precisely what the fossa in man contains or serves for before its 

 " glutealization " is still uncertain, an appeal to several of the dissect- 

 ing rooms having thus far proved luisuccessful owing to the dearth 

 of adolescent cadavers. 



As further points of interest, there may be nienlioncd the follow- 

 ing: The fossa in a distinguishable form may ajipear before or after 

 the first stages of the gluteal ridge; it may remain completely absent 

 while the ridge develops; and it may persist throughout life without 

 anv marked gluteal ridge or with any degree of this ridge, though the 

 more developed the ridge, the more likely is its encroachment upon 

 the fossa. Finally, the hollow is earlier than, as well as wholly inde- 

 pendent of, the third trochanter, though this may extend over, or even 

 develop within, the uppcr-to-middle reaches of the hollow and dimin- 

 ish its lumen accordingly. Notwithstanding the seeming — and prob- 

 ably largely real — independence of the fossa and the gluteal ridge, 

 a certain amount of reciprocity appears to exist during life, between 

 the fossa and the ridge : where the fossa is absent, the ridge in general 

 will be found to be more distinct than where the fossa exists. 



The incidence of the hypotrochanteric fossa dififers in various 

 human races and other groups, but these differences are neither great 

 nor always conformable to general racial affinities. Moreover, the 

 ordinary comparative data, it is now plain, are not pure enough, em- 

 bracing as they do adults of all ages and not presenting in all the 

 groups the same age distribution. They are biased, in other words, 

 by irremediable differences in the important age factor. 



