418 0. C. Marsh—American Jurassic Dinosaurs. 
THe ScaputaR ARCH. 
The scapular arch in the present species is fortunately better 
known than that of any other Dinosaur hitherto discovered. 
In Plates XII and XII 
found. They are sub-oval in outline, concave above, an 
thickened in front, and shows a distinct facet for union with 
the coracoid. The posterior end is thin and irregular. 
Tue PresacraL VERTEBRA. 
in Birds. In the posterior cervicals, the ribs become free. 
ties, while those farther back have only one large foramen in 
each side of the centrum, as in the dorsals, 
