of the United States. H 



View of the Natural Families of the System adopted in the 

 classification of the North American Birds. 



Birds are vertebrated, warm-blooded, oviparous animals, 

 formed for flying ; breathing by lungs : lungs undivided, 

 attached to the ribs, covered by a membrane perforated with 

 large holes ; heart bilocular and biauricular ; a corneous 

 edentate bill ; skin feathered ; two wings and two feet. 



In the present state of the science, they form the second 

 class of the first type of the animal kingdom. 



SUBCLASS I. 



Hind toe articulated on the same plane with the fore toes, 

 and bearing on the ground its whole length ; formed far 

 grasping. 



ORDER I. ACCIPITRES. 



Feet ambulatory : bill hooked, with a cere : nails retractile. 



1. Vulturini. Head naked. 



2. Rapaces. Head feathered. 



* Diurni. Eyes lateral. ** Nocturni. Eyes in front. 



ORDER II. PASSERES. 



Feet ambulatory, gressorial, or scansorial. 

 TRIBE I. scajvsores. Toes two before, and two behind, 

 § Anterior toes divided, or united only at base. 



3. Psittacini. Bill hooked, with a cere : none of the toes 



versatile. 



4. Frugivori. Outer hind toe versatile, connected with the 



fore toes by a membrane. 



5. Amphiboli. Outer hind toe versatile, free. 



* Bill ciliated. ** Bill not ciliated. 



6. Sagittilingues. Bill straight ; none of the toes versatile. 



