THE PELVIS IN BIRDS. 



251 



end, into the formation of the acetabulum, and then passes 

 backward and downward as a comparatively slender, curved, 

 bone, nearly parallel with the ischium. It is united with its 



Fig. 86.— a, lateral; and B, dursal, Tiew of the pelvis of a Fowl. *S^., sacrum ; 77., iUuih 

 /s., ischium; P&., pubis ; .4m., acetabulum. 



fellow only by fibrous tissue. Neither the ischia, nor the pubes, 

 unite directly with the sacrum. Very few birds present any 

 important deviation from this structure of the pelvis. In it- 

 nanvus, Casuarius, Dromceus, Apteryx, Dinornis, the ischium 

 is not united with the backward extension of the ilium by bone. 

 In Hhea, the ischia unite with one another beneath the verte- 

 bral column, and the vertebrae in this region are very slender 

 and imperfectly ossified. In Struthio, alone, among birds, do 



