318 Mr. Yarrell on the Organs of Voice in Birds. 



or compass of voice, than those provided with five pair ; but it 

 will be seen by a reference that the insertion of the principal 

 muscle shortening the bronchial tube, in the Parrots is much 

 lower down than in any other birds ; nor do any of the song- 

 birds possess the power of altering the size of the aperture at 

 the bottom of the tube of the trachea. Considerable advantage 

 is supposed to be afforded the Parrots by their soft, fleshy, 

 human-like tongue ; yet it cannot be denied that the Raven, 

 Magpie, Jay and Starling produce a close imitation of the 

 human voice with tongues long, slender and horny. The cele- 

 brated Mocking-bird of America, which I have once had an 

 opportunity of examining, has an organ of voice and tongue 

 precisely similar to our own Song-thrush. 



The organs of voice in the Mammalia, possessing chorda vo- 

 cales, have been considered to bear some relation to musical 

 instruments with strings ; and those of birds, to wind instru- 

 ments. Among the latter, (with most of which there are some 

 points of similarity,) they appear to me to have a closer resem- 

 blance to the French horn than any other ; the bronchiae per- 

 forming the same of?ice as the lips of the musician, and the 

 muscles of the glottis, like the hand, governing the extent of 

 the other aperture. The voices of the Stanley Crane and De- 

 moiselle, with their single convolution in the trachea, are lower 

 in the scale of tone than those of the other species of the same 

 family having no such convolution ; and the Common Crane 

 with his elongated double convolution possesses a voice still 

 deeper than the Stanley Crane or Demoiselle. In this circum- 

 stance they also particularly resemble the French horn, the 

 performers upon which fix additional circles of tube upon their 

 instrument when required to take a part in any concerted piece 

 of music that is set in a low key. 



It will perhaps be objected, that the utmost extent of motion 



which 



