XIII 



PHYLUM CHORDATA 



385 



style around which the rectrices are arranged. The quadrate 

 usually articulates with the skull by two facets. The barbs of the 

 feathers have booklets. 1 



ORDER 1. STEREORxrraES. 2 



Including PJwrorhacos, Dryornis, and other genera from the 

 Eocene of South America. 



FIG. 993. Hesperornis regalis. The restored skeleton. (After Marsh.) 



ORDER 2. ODOXTOLCLE. 



Including Hesperornis(~FigM3), a large diving and swimming Bird, 

 from the Cretaceous of North America, and other less known genera. 



1 Except, perhaps, in Hesperornis. 



2 Recent investigations indicate that this is not a natural group, but that its 

 various genera will have to be distributed amongst other Orders of Carinatse. 



VOL. II C C 



