RAVEN. 



69 



were called by the sentinel on duty." — Fauna Boreali-Ame- 

 ricana. Swainson and Richardson, Part 11. page 290, note. 



The advantageous size of the organ of voice in the Raven, 

 and its perfect similarity to those of all our song-birds, in- 

 duced me to select it in illustration of this subject, although 

 in the quality of its tone there is no resemblance ; but it 

 should be borne in mind, that this bird possesses the power of 

 imitating the most difficult of all sounds, — the human voice, 

 for which numerous muscles appear to be necessary. The 

 illustrations here given, are exactly of the same size as the 

 parts themselves will be found in the bird, by any one who is 

 inclined to follow me in the examination. 



The organ of voice in birds may be considered as consist- 

 ing of four parts : the glottis, or superior larynx, the tube of 

 the trachea, the inferior larynx, with its muscles, and the 



