AVES. 61 



SUBGENUS STRIX, Sav. Screech Owl. 



Ear as large as in the former ; beak straight, bent only 

 towards the end ; no aigrettes on the head ; tarsi feathered. 



SUBGENUS SYRNIUM. 



Conch small and not occupying the half of the height of 

 the cranium ; no aigrettes ; feet feathered to the nails. 



SUBGENUS BUBO. 



Conch small ; aigrettes. 



SUBGENUS NOCTUA, Savig. Chouette. 



Ears level with the head ; no aigrettes ; circle of feathers 

 small ; toes naked. 



SUBGENUS SCOPS. 



Ears level with the head ; aigrettes ; naked toes. 



ORDER II. PASSERINE. 



Four toes, three before and one behind, which distinguishes 

 them from the Climbers ; tarsi weak and short, which sepa- 

 rates them from the Waders ; exterior toes united by a short 

 membrane, which removes them from the Palmipedes. The 

 character of the beak and nails, joined with the preceding, 

 separates them from Birds of Prey. The stomach is a mus- 

 cular gizzard. Length of wing and extent of flight variable. 

 Sternum has a single notch on each side, except in some 

 genera, where there are two. Food consists of fruits, insects, 

 grain, according to the thickness of the beak. Five families, 

 of which the four first include birds whose exterior toes are 

 only united by one or by two phalanges. Plate 17 only con- 

 tains the two first. 



FAMILY I. DENTIROSTRES. 



Beak notched on both sides of the point. Ten remarkable 

 genera distinguished by the form of the bill. 



