OwLs. RAPACES. STRIX. 49 
its mode of life; im the former, the pupil being capable of 
great dilatation, and formed, by its particular prominence, 
for collecting the horizontal and dim rays of twilight; and 
being also furnished with a strong nictitatmg membrane, that 
serves, upon occasion, to defend it from the glare of day, at 
the same time that it allows the bird to see with sufficient dis- 
tinctness for avoiding any sudden danger or surprise. 
The external orifices of the ears are very large and com- 
plex, generally furnished with a valve, and situated imme- 
diately behind the eyes. In consequence of this formation 
and disposition, they are alive to the slightest noise, and not 
even the rustling of a mouse can escape their notice. The 
flight of the owl, when disturbed during the day, is abrupt 
and unsteady, but, at night, it skims along in search of its 
prey with great facility ; the delicate and downy texture of 
its plumage, producing the peculiar buoyancy which must 
have been generally remarked in the flight of these birds. 
The genus is usually divided into two sections ; horned or 
eared owls, such as have a tuft of elongated feathers on each 
side of the forehead, and smooth-headed owls, or those desti- 
tute of the lengthened feathers. ‘This second section has 
been subdivided by some authors into a third, called accipi- 
trine; but as the gradation from one to the other is almost 
imperceptible, and the characters upon which they have at- 
tempted to establish this subdivision are far from being dis- 
tinct, I have thought it quite sufficient for the general pur- 
poses of science to adhere to the two-fold division. 
The British Fauna enumerates four species in each sec- 
tion, of which two in the eared owls, and three in the smooth- 
headed, are indigenous; the others are but occasional visi- 
tants. 
Hornep Owts. SMOOTH-HEADED OwLs. 
Great-horned or Snowy Owl, Strix Nyctea, 
Eagle Owl, Strix Bubo. Barn Owl, iS. Flammea. 
Long. eared Owl, S. Otus. Tawny Owl, S. Stridula. 
Short-eared Owl, S. Brachyotos. | Little Owl, S. Passerina, 
Little-horned Owl, —_S. Scops. 
