Mr. YAnRELL on the Organs of Voice in Birds. 321 
Fig. 9. 10 & 11. Front, back and side views of part of the tra- 
chea of the Raven (Corvus Corax). 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. 
Tas. XIX. 
Trachea of the Spoonbill (Platalea leucorodia) in situ. 
Tas. XQ 
: 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. 6. Point of divarication. 
c, C. The bronchie. d,d. The single pair of mus- 
cles of voice. - 
Tan. XKL 
Fig. 1. Trachea of the Wood Grouse (Tetrao Brogalius), half 
the natural size. a. The loose portion. c,c. The 
bronchiz. 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 (Anas fusca). d, d. Sterno-tracheal mus- 
cles. e, e. The farculo-tracheal muscles “we The | 
= ay e m FS 
A — XVII. 4 Syn- 
