180 MEMOIRS OF THE CARNEGIE MUSEUM 



" These latter also indicate that the canal formed by these processes, the centra 

 of their vertebrse and the ilium, is larger on the right side than on the left, and that 

 it is the first obliterated on the left side. 



" In carbo neither the sacrals nor the second post-sacral bear parapophyses, 

 although these are present on the first post-sacral, uniting it firmly with the ilium. 



" In one example of urile, slender, but well-marked parapophyses connect the 

 two sacrals with the ilia. 



" In another and much smaller specimen the second sacral has a parapophysis 

 on the left side, there being no parapophyses on the first sacral. 



" In both specimens of urile the first, but not the second, post-sacral bears para- 

 pophyses. Finally, dilophus has strong parapophyses on the second sacral and first 

 post-sacral, but none on the second post-sacral. 



"The variation in the sacral region of these specimens is not only interesting in 

 itself, but interesting from the fact that it is unusual for parapophyses to be present 

 at all on the true sacral vertebrae of birds. 



"Viewed from above the ridge formed by the confluent spinous processes of the 

 ' sacrals ' is wider than in carbo, and the interpophysial foramina are nearly closed, 

 while in carbo they are very open. 



"Although these characters depend to some extent on age, they do not entirely, 

 and the same differences exists between the ' sacra ' of urile and dilophus as between 

 those of perspicillatus and carbo. 



"The pelvis is much more rugose than in carbo, all attachments for muscles be- 

 ing strongly emphasized. 



"The anti-trochanter is placed further back than in carbo, and is much more 

 rounded, thus affording more play to the femur. 



" Just back of the anti-trochanter the outer edge of the ilium is raised and thick- 

 ened, forming a fiat, subtriangular spot, but proportionately smaller than in per- 

 spicillatus. 



" Back of this flattened portion the dorsal edge of the ilium is bent outward, 

 making this part of the ilium outwardly concave, where in carbo it is convex. 



"The post-ilia of carbo and dilophus round gentl}' outward and downward 

 throughout their entire length from their junction with the diapophyses. 



"Viewed from the side the dorsal outline of the 'sacrum' is slightly decurved, 

 while that of cao'bo is very nearly straight and the same difference exists between 

 urile and dilophus. 



"The acetabulum is slightly larger and forms more nearly a perfect circle than 

 in carbo. 



