42 Proceedings of the Royal Irish Academy. 



surface of the shaft, i.e., behind the flange, the vastus intermedins occupying 

 the front of the bone and the anterior aspect of the ridge. The presence of 

 the flange was afterwards verified in the skeleton. It seems likely, therefore, 

 that in at least some cases this medial extension is associated with alteration 

 in the proportionate attachments of the vastus medialis and intermedius, the 

 formation of the flange providing a greater area for the attachment of both 

 these muscles. In two specimens from this collection, in which this flange 

 was only developed to a small extent, a condition is present bearing out this 

 view. Usually the spiral line to which the vastus medialis is attached 

 appears to be directly continuous with the anterior intertrochanteric ridge, as 

 the muscle arises from both. If the muscle be pushed round to the medial 

 surface, we would expect this continuity to be less manifest, and in the 

 specimens here described this is found to be the case. The spiral line can be 

 traced up to the medial flange, and there a somewhat rough area is present, 

 indicating the upper attachment of the muscle. 



The medial flange appears to be of the nature of a buttress for the upper 

 end of the shaft, and I found, on making sections of recent specimens in 

 which the flange is present, that the spiral lamellae are more concentrated in 

 this region than in other bones. 



High degrees of platymery are usually associated, according to Hepburn 

 and Manouvrier, with a pilastered condition of the shaft, but, as the former 

 remarks, high degrees of either may be present independently, and so 

 probably result from different causes. The pilastric index in this series 

 average 109; the inner fossae were flat, the outer in some cases concave. 

 The latter condition indicates probably a marked development of the vastus 

 intermedius. Pilastering is often seen in slender femora, particularly if the 

 specimen be one of recent times, but is not confined to bones of this type. 

 It is noteworthy that many pilastered bones show strong development of 

 gluteus maximus, even if there be no distinct platymeria, and that this muscle 

 would undoubtedly, under certain circumstances, tend to pull the upper end 

 of the bone backwards, and so accentuate its curvature. It is necessary to 

 remark that there may be strong prominence of the linea aspera without 

 marked hollowing of the outer pilastric fossa. I think this is more common 

 in modern pilastered bones. The index in this collection was determined by 

 Hepburn's method. Only five specimens were suitable for the estimation ; 

 the lower index was 96-2, and the highest 112. 



The series show that the most platymeric bones are not necessarily the 

 most pilastered. The collection is not sufficiently large for any dogmatic 

 statements, but it conveys the impression that bones with marked curvature 

 of the shaft do not show a well-developed medial flange. 



