8 Mr. C. W. Andrews on a Group of 



ischium does not unite posteriorly with the ilium nor the 

 pubis with the ischium. In Phororhacos the pubis is very 

 small, and indeed, except for the shoi't distance during 

 which it forms the inferior boundary of the passage for the 

 obturator internus muscle, it fuses with the lower border of 

 the ischium, beyond which it does not seem to have extended, 

 although the posterior prolongations may have been broken 

 away. The compressed form of the pelvis and the elonga- 

 tion of the post-acetabular portions of the ilium are notable. 

 Prof. Milne-Edwards has remarked that the larger the pre- 

 acetabular ilium the better a bird is adapted for walking, 

 while the post-acetabular portion increases in length in pro- 

 portion as the bird is better adapted for swimming. This, 

 no doubt, is generally true, and is well illustrated in Hesper- 

 ornis and Podicipes, in the former of which the post-ace- 

 tabular ilium is about three times the length of the pre- 

 acetabular portion, and in the latter about twice as long. 

 In Phororhacos the proportions are nearly as in Podicipes, 

 but, considering its long powerful legs and digits provided 

 with hooked claws, it is difficult to imagine that it was a 

 good swimmer. The pelvis of Cariama, though shorter and 

 broader in the post-acetabular region, is nevertheless somewhat 

 similar to that of Phororhacos, and this likeness is more 

 striking when the pelvis is viewed from the side. The 

 relation of the ischium to the ilium is exactly similar, and 

 the pubis, which is extremely slender, is closely applied to 

 the ventral border of the ilium, with which, however, it is 

 not co-ossified in the specimen examined. The posterior 

 extremities of the pubes extend beyond the ischia and are 

 expanded : in the fossil these may easily have been lost. 

 The pelvis of Psophia is not so similar, and those of the 

 Tinamou and of Cathartes are still more unlike. 



The femur is long, straight, and comparatively slender. 

 The head rises above the slightly developed trochanter ; in 

 this respect the bone is similar to that of Gastornis (although 

 in that bird the trochanter is much larger) and Phalacro- 

 corax. In Grus, Cariama, Psophia, and Aptornis the tro- 

 chanter is largely developed and rises above the head. In 



