Plate XXII. 



Figs. 1-4, propodial bone of young plesiosaur, from Niobrara Cretaceous. 



X3/4- 



Fig. 5, atlanto-axis of Dolichorhynchops osborni, from the side. X3/4. 



ati, atlantal intercentrum; axi, axial intercentrum; n, atlantal neurapophysis; 

 o, odontoid; ;-, pit for reception of axial rib; na, axial neurapophysis; 2, zyga- 

 pophysis. 



