ON THE SENSES OF BIRDS. 49 



Trachea, which in man do not amount to twenty, in the 

 Ostrich lately dissected at the Zoological Society, it was 

 about four feet long, and the rings in it were more than two 

 hundred. The sternum in the Ostrich is not only without 

 the keel, but it is exceedingly small when compared to its 

 size in that of other Birds. 



Although Birds have only two legs, yet the bones of their 

 wings, when examined anatomically, correspond in a grea 

 degree with the fore limbs of many of the mammalia. It is 

 chiefly in their use and covering that they differ from qua- 

 drupeds and man. But the bones of Birds differ in another 

 particular, namely, they are most of them hollow, and have 

 communication with the air cells in their bodies, by which 

 they are rendered more buoyant. 



Birds have no external ears, a few of the Owl tribe ex- 

 cepted, although their organs of hearing are, beyond question, 

 acute, as their various notes and modulations of sound 

 sufficiently evince. It has, however, been supposed, that 

 they have no idea of harmony, as they never sing in concert; 

 they nevertheless imitate sounds with great facility ; so much 

 so, indeed, that Mr. Barrington (see below,) thinks all the 

 notes of song birds are imitations. It is chiefly, I appre- 

 hend, on this sense, and on that of sight, that birds depend 

 for their safety and preservation. The touch, taste, and smell, 

 being in the generality of the tribe of a secondary order. 



The organ of smell is said in the Gannet to be wanting; 

 but, in most birds, there is no reason to think that the 

 organ is absent ; yet, notwithstanding it has been generally 

 supposed that this sense is active in the rapacious tribes, 

 particularly the Vulture, some late observations seem dis- 

 tinctly to show that, in the pursuit of his prey, the Vulture 

 is guided by his sight rather than by his smell. Still there 

 is reason to believe, that many of the rapacious tribe are 



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