RAVEN. 



269 



The organ of voice in Birds generally may be regarded as 

 composed of four parts : (i.) the glottis or superior larynx, 

 (ii.) the windpipe or trachea, (iii.) the inferior larynx or 

 syrinx, and (iv.) the bronchial tubes or bronchi. The glottis 

 opens into the mouth at the root of the tongue. Fig. 1 of 

 the accompanying woodcuts shews (a, a, a) the principle 



Fig. 4. 



cartilage, lying upon the pharyngeal portion between the 

 hyoid or tongue-bones, and apparently performing the 

 double office of the thyroid and cricoid cartilages in 

 Mammals. It is thin and nearly triangular, the posterior 

 corners curving upwards. In the midst is the long and 

 narrow orifice of the windpipe, behind which the surface 

 is beset- with papillffl pointing backward, and serving in the 

 absence of an epiglottis, or cover of the opening, to direct 



