176 DR. R. BROOM ON THE STRUCTURE AND [June 4, 



in this skeleton, but it is situated immediately below the oblique 

 ridge not tar from the lower border of the acetabulum. The lower 

 part of the pubis is moderately flat, and does not extend farther 

 forward than the level of the lower tubercle. The anterior border 

 between the lower tubercle and the symphysis is straight, as if for 

 the articulation of a cartilaginous epipubic element. There is a 

 long articulation between the pubis and the ischium below the 

 obturator foramen. 



The ischium (is.) in Udenodon gracilis is proportionally very 

 considerably smaller than in the Dicynodon pelvis figured by 

 Lydekker, and looks much less downwards than in that specimen. 

 From the point where the ischium meets the ilium the posterior 

 border curves downwards and then backwards, ending abruptly at the 

 ischial tuberosity. From the tuberosity the lower border curves 

 gently round to meet the pubis. The lower part of the ischium is 

 flat except in being slightly concave in the neighbourhood of the 

 obturator foramen. Bound the posterior border of the acetabulum 

 the ischium forms a prominent ridge, but the ridge formed by the 

 ischium is not continuous with that formed by the pubis, a gap 

 occurring at the ischio-pubic suture. From the acetabular border 

 a prominent thickening or ridge runs backwards to the upper end 

 of the ischial tuberosity. 



There is no evidence of any marsupial bones, and from the con- 

 dition of the skeleton this may almost be taken as conclusive proof 

 that such bones did not exist in Udenodon. There is evidence, 

 however, in favour of there having been a cartilaginous epipubis. 



In Udenodon baini the ilium is very similar to that in U. gracilis, 

 but the ischium is proportionally considerably larger though its 

 general characters are very similar. The obturator foramen (f.ob.) 

 is oval with the long axis directed antero-posteriorly and situated 

 close under the border of the acetabulum. The long axis of the 

 foramen measures about half the diameter of the neck of the ilium. 



Femur. 



In Udenodon gracilis the right femur has its posterior side well- 

 displayed, and as its upper half has been broken loose its anterior 

 side can also be examined with the exception of the head. 



In its general proportions the femur (Plate XVII. fig. 5, fm.) 

 agrees with that of the Monotremes, though in its characters it 

 differs somewhat. It is much flattened throughoutits whole length, 

 and considerably broadened out both at its upper and lower ends. 

 From the head to the greater trochanter the measurement is nearly 

 three times as great as that across the middle of the shaft. From 

 a little below the middle of the bone, the outer border forms an 

 almost straight line to the top of the great trochanter. The inner 

 border curves very markedly inwards to the head, and the curve is 

 interrupted by the presence of the small trochanter, which forms a 

 small but very distinct inwardly directed ridge. On the anterior 

 surface of the bone so far as displayed is a small vertical groo\e a 



