﻿322 OS THE CLASSIFICATION OF BIRDS. 



noiseless flight : the quills themselves are unusually 

 broad, while the barbs, no less than the general plu- 

 mage, is remarkably soft and lax, in order to permit a 

 free escape of the air in all directions. That these cir- 

 cumstances, however, should not diminish the powers 

 of flight too much, the wings are generally rather long, 

 and the four outer quills have that abrupt sinuosity on 

 their inner webs which is so universal among the swift- 

 flying falcons. 



(258.) An exquisite sense of hearing is another 

 peculiarity of these birds — a faculty which is essential 

 to the discovery of their prey in the dusky hours of 

 twilight. The great size of the head is well known, 

 and its apparent disproportion to that of the body is 

 rendered necessary, on account of its containing several 

 large cavities, which communicate internally with the 

 ears, and thus tend to the unusual development of those 

 organs. The external orifice is, in general, enormously 

 large, and, even in the aberrant species, generally exceeds 

 that of ordinary birds. In the typical examples, the 

 external opening is protected by a fleshy operculum, or 

 lid, thickly covered on the outside with feathers, and 

 as freely moveable as is a door on its hinges. But if the 

 faculty of hearing is so essential to an owl, how much 

 :::ore so is that of sight, when it has to pursue its prey 

 in the dark. Yet here again we trace, in a beautiful 

 and wonderful instance. the wisdom of God in the 

 creation/' The eyes, in the first place, are of an enor- 

 mous size : but as if this were not sufficient, they are 

 surrounded with two large concave disks — generally 

 composed of white and shining feathers, — for the pur- 

 pose of concentrating a greater extent of light to be 

 reflected upon the eye. which is placed in the centre. 

 There can be little doubt on this being the true use of 

 the facial disk in owls, although the circumstance ap- 

 pears never yet to have been touched upon. We all 

 know the effect upon our own sight, when, by looking 

 through the hand, as we would a telescope, we contract 

 the light, and are enabled to see further and much 



