NO. II CLASSIFICATION, BIRDS OF THE WORLD — WETMORE 23 



allied to one another than to their fellows, but the taxonomist may 

 discuss these at need as groups without imposing another burden on 

 a classification that now is highly divided. For the group names above 

 the family level, I believe it preferable to use suffixes that allow im- 

 mediate identification of the rank, coupled with a stem that, like the 

 family name, is based on a current generic term. Where ordinal and 

 subordinal names are both formed as Latin plurals there is possibility 

 of confusion. 



SYSTEMATIC LIST 

 Fossil groups in brackets 



Class Aves, Birds. 



[Subclass Archaeornithes, Ancestral Birds (fossil).] 



[Order Archaeopterygi formes, Archaeopteryx, Archaeornis 

 (fossil).] 

 [Family Archaeopterygidae, Archaeopteryx, Archaeor- 

 nis (fossil).] 

 Subclass Neornithes, True Birds. 



[Superorder Odontognathae, New World Toothed Birds (fos- 

 sil).] 

 [Order Hesperornithiformes, Hesperornithes (fossil).] 

 [Family Hesperornithidae, Hesperornis (fossil).] 

 [Enaliornithidae, 1 Enaliornis (fossil).] 

 [Baptornithidae, Baptornis (fossil).] 

 [Superorder Ichthyornithes, Ichthyornis and Allies (fossil).] 

 [Order Ichthyornithi formes, Ichthyornithes (fossil).] 



[Family Ichthyornithidae, Ichthyornis (fossil).] 

 [Apatornithidae, Apatornis (fossil).] 

 Superorder Impennes, Penguins. 

 Order Sphenisciformes, Penguins. 



Family Spheniscidae, Penguins. 

 Superorder Neognathae, Typical Birds. 

 Order Struthioni formes, Ostriches. 



[Family Eleutherornithidae, Eleutheromis (fossil).] 

 Struthionidae, Ostriches. 

 Order Rheiformes, Rheas. 



Family Rheidae, Rheas. 

 Order Casuariiformes, Cassowaries, Emus. 

 Family Casuariidae, Cassowaries. 

 Dromiceidae, Emus. 

 [Dromornithidae, Dromomis (fossil).] 



1 Position provisional. 



