THE CLASSIFICATION OF BIRDS 29 



4. STEGANOFODES. 



The Steganopodes differ from all other birds in having the 

 hallux united to the second digit by a web. They agree with the 

 Herodiones in having altrical young, and in having no basiptery- 

 goid processes. They may be divided into five families. The 

 Phaetontidce are peculiar in having a large nasal aperture, and in 

 having the palatines not coalesced. The Phalacrocoracidce agree 

 with the Phaetontidce, but differ from the others in having the 

 dorsal vertebra furnished with ventral processes. The Fregatidce 

 are peculiar in having the feet of the coracoids coalesced with 

 each other. The Pelecanidce agree with the Phaetontidce and differ 

 from the others in having the palatines narrowed for some dis- 

 tance from the pterygoids and expanded for some distance after 

 they separate. The Sulidce scarcely differ from the Phalacrocora- 

 cidce in the arrangement of the palatines. 



Externally the birds in these five families differ remarkably. 

 The nearly straight bill of the Phaetontidce and the Sulidce, the 

 boldly-hooked bill of the Fregatidce, and the pouched bill of the 

 Pelecanidce are familiar examples of the small taxonomic value 

 that can be attached to the external form of the bill-. The range 

 of the Phaetontidce and the Fregatidce is circumtropical, that of 

 the Pelecanidce is also subtropical, and that of the Phalacrocora- 

 cidce and Sulidce is also subarctic. 



FALCONIFOKMES. 



The Falconiformes, like the Ealliformes, are aquincubital, 

 holorhinal, and have normal plantars; but the hallux is well- 

 developed and situated on the same plane as the other digits. 

 The nasal septum is ossified, causing the nares to be impervious, 

 and the bill is furnished with a cere. The spinal feather-tract is 

 well defined on the neck by the lateral bare tracts, and is forked 

 between the shoulders. The young are hatched in a helpless 

 condition, and are fed by their parents in the nest for many days. 

 In the arrangement of their palatines they vary somewhat. The 

 Psittaci are directly desmognathous, the maxillo-palatines coal- 

 escing across the middle line. The Accipitres are more or less 

 desmognathous, but the ossified nasal septum often has to do duty 

 to make them so. The Striges might almost be regarded as schizog- 



