88 ODOXTORXITHES. 



The Femur. (Plate XIII.) 



The femur of Hesperornis regalis is remarkably short and stout, more 

 so than in any known bird, recent or fossil. In its general features, it 

 resembles the fenmr of Pocliccps, but the shaft is much stouter, and is flat- 

 tened in an antero-posterior direction. The head is large, and well rounded, 

 and is supported by a short and powerful neck. There is a deep pit on 

 the inner superior surface of the head, for the insertion of the round 

 ligament. The great trochanter is very large, and extends outward a 

 considerable distance beyond the shaft. Its upper surface is below that of 

 the head, and there is a concave depression seen between the two, when 

 the femur is viewed from the front. The whole upper end of the femur, 

 outside of the head, is covered by an articular surface, which plays against 

 the anti-trochanter of the ilium. 



The shaft of the femur is somewhat curved, with the convexity 

 forward, and is marked on the posterior, inner, and outer surfaces by 

 strong prominences for the attachment of muscles. The shaft contains no 

 pneumatic foramina, but there is a large medullary cavity, in the bone, as 

 shown in the two sections represented below : 



24.— Transverse section through shaft of femur of Hssperornis regalis; (No. 1472), top view; 

 natural size. 

 Figure 25.— Transverse section of same bone (No. 1489), just above distal articulation, m. medullary cavity. 



The distal end of the femur is much expanded transversely, and, of 

 the two anterior condyles, the outer is much the larger. The groove 

 between these condyles is shallow, and on a line with the axis of the shaft. 

 On the posterior distal surface, there is a strong obtuse ridge which plays 

 between the upper ends of the tibia and fibula. The ridge passes vrpward 

 and outward, and ends nearly opposite the outer margin of the shaft. 



