CLASSIFICATION" OF BIRDS. 149 



The Class of Birds, like most other classes in the Ani- 

 mal Kingdom, has been variously divided.* This is owing 

 partly to real progress in science, and partly to the fact 

 that different naturalists attach different decrees of ira- 



O 



portance and different meanings to the various parts of 

 the structure of these animals. Huxley and some others 

 recognize only three Orders of Birds : 



1. CAKIXAT^, from the Latin carina, a keel ; the birds of this 



order have the sternum raised into a ridge or keel. Here be- 

 long all the ordinary birds, as Falcons, Woodpeckers, Spar- 

 rows, Crows, Pigeons, Grouse, Herons, Ducks, etc. 



2. RATIT^, from the Latin ratis a raft ; the birds of this order 



have the sternum flat or keel-less, that is raft-like ; as the 

 Ostriches, Apteryx, etc. 



3. SAURUR^E, so named from the Greek saura, a lizard, and oura 



a tail ; the vertebrae of the tail are numerous, thus making it 

 long like that of a lizard ; as the Archseopteryx (fossil).f 



*The Smithsonian Institution lias adopted, provisionally, the following 

 arrangement of the divisions and subdivisions of the Class of Birds : 



SUB-CLASS I. INSESSORES. 



ORDER I. PASSERES, including Oscines, as the Thrushes, Warblers, Spar- 

 rows, etc., and Clamatores, as the Tyrant Flycatcher, etc. 



ORDER II. STRISORES, as the Kingfishers, Goatsuckers, Humming-birds, 

 etc. 



ORDER III. ZVGODACTYLI, as the Cuckoos, Woodpeckers, Parrots, etc. 



ORDER IV. ACCIPITRES, as the Falcons, Owls, Vultures, etc. 



ORDER V. PCLLASTR^E, as the Pigeons, Curassows, etc. 



SUB-CLASS II. CURSORES. 



ORDER VI. GALLING, as the Turkeys, Grouse, Pheasants, etc. 

 ORDER VII. BREVIPENNES, as the Ostriches. 

 ORDER VIII. GRALI^E, as the Plovers, Snipes, Herons, etc. 



SUB-CLASS III. NATATORES. 



ORDER IX. LAMELLIROSTRES, as the Swans, Geese, Ducks, etc. 

 ORDER X. STEGANOPODES, as the Pelicans, Gannets, Frigate-birds, 



Cormorants, Snake-birds, and Tropic-birds. 



ORDER XI. LONGIPENNES, as the Gulls, Terns, Albatrosses, Petrels, etc. 

 ORDER XII. PYGOPODES, as Divers, Grebes, Auks, and Penguins. 



t In fossil forms of birds there are perhaps two distinct orders : 



1. Saururae, represented by Arohceopteryx. 



2. Ichthyornithides, represented by Ichthyornis and Aptornls. 



