Mr. Yarrell on the Organs of Voice in Birds. 321 



Fig. 9. 10 «Sc 11. Front, back and side views of part of the tra- 

 chea of the Raven {Corvus Cor ax), d. The sterno- 

 tracheal muscle, e. The long anterior tensor, f. The 

 long posterior tensor, g. The short anterior tensor. 

 h. The short posterior tensor. 

 12. Side view of the same trachea, the muscles partly de- 

 tached for distinction. Letters of reference the same. 



Tab. XIX. 

 Trachea of the Spoonbill {Platalea leucorodia) in situ. 



Tab. XX. 

 Fig. 1. Trachea of the Curassow (Crax Alector) in situ, seen 

 from before. 

 2. The same trachea seen from behind, a, a. The con- 

 volutions of the tube. b. Point of divarication, 

 c, c. The bronchiae. d, d. The single pair of mus- 

 cles of voice. 



Tab. XXI. 



Fig. 1. Trachea of the Wood Grouse (Tetrao Urogallus), half 

 the natural size. a. The loose portion, c, c. The 

 bronchiae. d. The furculo-tracheal muscles, e, e. The 

 sterno-tracheal muscles. 

 2 & 3. Inside views of both halves of the trachea of the 

 Velvet Duck (Anasfusca). d, d. Sterno-tracheal mus- 

 cles, e, e. The furculo-tracheal muscles, a, a. The 

 laryngeal cavity. 



2 T 2 XVIII. A Syn- 



