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XVII. On the Organs of Voice in Birds. By William Yarrellt Esq. 



F.L.S. 



Read June 2 and 16, 1829. 



Th e very liberal manner in which the Linnean Society did me 

 the honour to illustrate a former paper on the Tracheae of Birds, 

 has been an additional inducement with me to render this sub- 

 ject as complete as my means of observation would allow : I 

 therefore now submit descriptions and figures of the numerous 

 muscles attached to the different parts of the windpipes of birds, 

 by the action of which their varied and extraordinary powers of 

 voice are produced, with representations of the tracheae of four 

 birds, which, though not all entirely unknown, are each of them 

 illustrative of a portion of this subject, and have not beeii 

 hitherto so represented as to afford a correct idea of their local 

 situation or peculiarities. 



The organ of voice in birds may be considered as consisting 

 of four parts ; the glottis or superior larynx, the tube of the 

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

 and the variety of modulation birds are known to possess has its 

 corresponding variety of forms. The glottis or superior larynx 

 opens into the mouth at the root of the tongue. The orifice is 

 long and narrow, encircled by two pair of muscles which govern 

 the size of the aperture, and constitute one of the accessory 

 means by which the sound of the voice is regulated. Birds 

 have no epiglottis or covering over this aperture to prevent any 



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