American Osprey 195 



itself ; tarsus and toes feathered, or at any rate covered 

 with bristles ; hind toe jointed on the same level as the 

 others. 



Key of the Families and Genera.* 



A. Claw of the middle toe serrate on the inside edge, middle and 



inner toes approximately equal (Aluconidce). Aluco, p. 196. 



B. Claw of the middle toe not serrate ; middle toe alv.'ays exceeding 



inner toe (Strigidce), 



a. Ear-tufts jiresent and generally conspicuous. 



a^ Large ; wing over 14 ; tail nearly concealed below by the 

 lengthened under tail-coverts. Bubo, p. 208; 



b^ Medium; wing 10 to 12; tail-coverts not abnormally long ; 

 toes feathered to the claws. Asio, p. 197. 



c^ Small ; \^"ing under 8 ; toes bristly or naked. Otus, p. 204. 



b. Ear-tufts absent. 



a^ Larger ; wing over 12. 



a^ Bill concealed by frontal feathers ; plumage chiefly white 



Nyctea, p. 210. 

 b* BiU yellow, not concealed ; plumage not white. 



Strix, p. 200. 

 b^ Meditun ; wing 6 to 8. 



a^ Tarsus hardly exceeding the middle toe without claw ; 



toes densely feathered. Cryptoglaux, p. 202. 



b^ Tarsus about twice the length of the middle toe without 



claw ; toes bristly, not feathered. Speotyto, p. 211. 



c^ Small ; wing under 4 ; nostrils well within the swoUen cere ; 



toes bristly. Glaucidium, p. 213. 



Family ALUCONID^. 



This family, containing the Barn-Owls, is distinguished 

 externally from the other Owls by having the claw of 

 the middle toe pectinate or serrated along its inner side, 

 and the middle and inner toes about equal in length. 

 Anatomically the sternum is entire — not notched 

 posteriorly and the clavicles or furculum are anchylosed 

 to the sternum. 



• The names of the families of most of the genera have been changed in accordance 

 with the new A.O.U. Checklist. 



o2 



