BIRDS OF NORTH AND MIDDLE AMERICA. 619 



The Bubonidse are more nearly cosmopolitan than the Tytonidse, 

 being absent only from Polynesia, representatives of the family 

 existing in Madagascar, New Zealand, the Hawaiian islands,^ and 

 the Arctic districts. Thirty recent genera and nearly tliree hundred 

 species and subspecies are recognized, of which eighteen genera and 

 about one hundred species (including subspecies) are American. 



Owing to the circumstance that the most unportant structural 

 characters are not evident in dried skins, a satisfactory arrangement 

 of the genera is hardly possible at this time. If all the genera had 

 been as carefully examined from freshly killed specimens as have 

 those of northern Europe, by Dr. CoUett, the matter would be greatly 

 simplified, since the form, size, etc., of the external ear-opening affords 

 an excellent character, though a classification based on this alone 

 would probably be far from perfect. Nitzsch, Pycraf t, Hubert Lyman 

 Clark, and others have studied the osteology and pterylography of a 

 limited number of forms, and so far as their investigations have 

 extended much has been learned; but unfortunately a very large 

 proportion of the genera have not been available for study from 

 freshly killed or alcoholic specimens, and hence any arrangement 

 possible at the present time must be considered provisional only. 



KEY TO THE AMERICAN GENERA OP BUBONIDiE. 



a. External ear-opening extremely large, its vertical axis equal to at least half the 

 greatest height of skull, crossed by a median ligament or bridge, its margin (at 

 least the anterior one) produced into a dermal flap of greater or less width. 

 b. Head without distinct, if any, ear-like feather tufts; ear-orifice either in lower 

 part of the external ear-opening, below the transverse "bridge" or (left ear 

 of Cryptoglaux) on both sides of the latter. 

 c. Cranium conspicuously asymmetrical, abnormal on both sides; external ear- 

 openings broadly oval, of equal size, slightly asymmetrical, the marginal 

 flap nearly equally developed all round, relatively narrow in front; seventh 

 and eighth b primaries longest; two outer primaries with inner webs emar- 

 ginated; tail less than two-thirds as long as wing, nearly or quite truncate; 

 size small (wing 133-188 mm.). 

 d. Toes feathered (except in C. ridgwayi); ear-tufts very 



minute or obsolete Cryptoglaux (p. 622). 



dd. Toes wholly naked; ear-tufts distinct though very small. 



Gisella (extralimital).c 



a The single Hawaiian species is, however, one of nearly world-wide range {Ado 

 acci'pitrinus) . 



& Third and fourth from outside, not counting the rudimentary and concealed 

 eleventh primary. 



c Gisella Bonaparte, Ann. Sci. Nat. (Zool.), 4 ser., 1, 1854, 112 (nomen nudum) 

 Rev. et Mag. de Zool., vi (2), 1854, 541. (Type, Strix lathami Bonapa.Tte= Nyctale 

 harrisi Cassin). —Nyctalatinus "Kaup, 1854" Gray, Cat. Qen. and Subgen. Birds, 

 1855, 135. (Type, N. albipunctatus Kaui>=Nyctale harrisi Cassin.)— Nyctalitiyius 

 (emendation) Sclater and Salvin, Norn. Av. Neotr., 1873, 116. 



Colombia to southern Brazil; two species. (It is possible that "Cryptoglaux" ridg- 

 wayi, of which only the young is known, may belong to this genus. If so, the two 

 groups are hardly generically distinct.) 



