NORTH AMERICAN BIRDS. 



Family STRIGIDiE. — The Owls. 



Char. Eyes directed forward, and surrounded by a radiating system of feathers, 

 which is bounded, except anteriorly, by a ruff of stiff, compactly webbed, differently 

 formed, and somewhat recurved feathers ; loral feathers antrorse, long, and dense. 

 Plumage very soft and lax, of a line downy texture, the feathers destitute of an 

 after-shaft. Oil-gland without the usual circlet of feathers. Outer webs of the quills 

 with the points of the fibres recurved. Feathers on the sides of the forehead frequently 

 elongated into ear-like tufts ; tarsus usually, and toes frequently, densely feathered. Ear- 

 opening very large, sometimes covered by a lappet. (Esophagus destitute of a dilated 

 crop ; coeca large. Maxillo-palatines thick and spongy, and encroaching upon the 

 intervening valley ; basipterygoid processes always present. Outer toe reversible ; pos- 

 terior toe only about half as long as the outer. Posterior margin of the sternum doubly 

 indented ; clavicle weak and neai'ly cylindrical, about equal in length to the sternum. 

 Anterior process of the coracoid projected forward so as to meet the clavicle, beneath the 

 basal process of the scapula. Eggs variable in shape, usually nearly spherical, always 

 immaculate, pure white. 



The Owls constitute a very natural and sharply limited family, and tliough 

 the species vary almost infinitely in the details of their structure, they all 

 seem to fall within the limits of a single subfamily. 



They have never yet been satisfactorily classified, and all the arrange- 

 ments which have been either proposed or adopted are refuted by the facts 

 developed upon a close study into the true relationship of the many genera. 

 The divisions of " Night Owls," " Day Owls," " Horned Owls," etc., are 

 purely artificial. This family is mucli more homogeneous than tliat of the 

 FalconidcK, since none of the many genera which I have examined seem 

 to depart in their structure from the model of a single subfamily, though a 

 few of them are somewhat aberrant as regards peculiarities in the detail of 

 external form, or, less often, to a slight extent, in their osteological char- 

 acters, though I have examined critically only the American and European 

 species ; and there may be some Asiatic, African, or Australian genera 

 which depart so far from the normal standard of structure as to necessitate a 

 modification of this view\ In the structure of the sternum there is scarcely 

 the least noticeable deviation in any genus ^ from the typical form. The 

 appreciable differences appear to be only of generic value, sucli as a different 

 proportionate length of the coracoid bones and the sternum, and width of 

 the sternum in proportion to its length, or the height of its keel. The crania 

 present a greater range of variation, and, if closely studied, may afford a 

 clew to a more natural arrangement than the one which is here presented. 

 The chief differences in the skulls of different genera consist in the degree 

 of pneumaticity of the bones, in the form of the auricular bones, the com- 

 parative length and breadth of the palatines, and very great contrasts in the 



1 I have, however, examined the sterna only of Nyctca, Bubo, Otus, Brachyotus, Syrnucm, 

 Nyctale, and Glaucidium. 



