^889."'] PROCEEDINGS OF THE NATIONAL MUSEUM. 01 



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

 the centra of their vertebnc, and the ilium, is larger on the right side 

 than on the left, and that it is first obliterated on the left side. 



In carbo neither the sacrals nor the second post-sacral bear para- 

 pophyses, 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 para- 

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



Iu both specimens of urile the first, but not the second, post sacral 

 bears parapophyses. Finally, dilophus has strong parapophyses on the 

 secoud sacral and first post-sacral, but none on the second post-sacral. 



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

 teresting iu 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 proc- 

 esses of the ^sacrals" is wider than in carbo, and the iuterpophysial 

 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 exist 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 being strongly emphasized. 



The auti-trochanter is placed farther 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 thickened, forming a flat, subtriangular spot about an inch iu 

 length. 



This peculiar flattening of the ilia, taken in connection with the size 

 and rugosity of the pelvis, is sufficient to distinguish it from that of 

 other species. 



The ilium of urile has a flattened spot, but proportionately smaller 

 than in perspicillatus. 



Back of this flattened portion the dorsal edge of the ilium is bent out- 

 ward, making this part of the ilium outwardly concave, where iu carbo 

 it is convex. 



The post ilia of carbo and dilophus round gently outward and down- 

 ward throughout their entire leugth from their junction with the dia- 

 pophyses. 



Viewed from the side the dorsal outline of the "sacrum" is slightly 

 decurved, while that of carbo is very nearly straight, and the same dif- 

 ference exists between urile and dilophus. 



The acetabulum is slightly larger and forms more nearly a perfect 

 circle than in carbo. 



The ilio ischiatic foramen is subelliptical and wide, the longitudiual 



