320 . .Mr.YannELL on the Organs of Voice in Birds. 
Fig. 8. Front view of the same trachea. a. Part of the tube. 
b. The triangular bone between the c i 
bones. 
9, Side view of the trachea of the feci (Gori Corax). 
a. Part of the tube. b. Point of divarication. c. Bron- 
chia outside. 
10. Another view of the same; one ii being removed 
to show the inner portion (membrana tympaniformis) 
of the other, letter c. 
11. Bone of divarication in the Raven (Corvus Corax), seen 
from below. a*. Posterior part. a,a. Cross-bone. 
b, b. The sides. 
12. Lower part of the trachea of the Great Black- backed 
Gull (Larus marinus). b. The triangular bone of di- 
varication ; and a, a. The triangular cross-bone. 
STAP AYEI. 
Fig. 1&2. Front and side views of a trachea having one pair of 
muscles of voice. a,b, &c. Refer as before. d,d. The 
first pair of muscles. 
3. Side view of a trachea with two pair of muscles of voice. 
d. Sterno-tracheal or first pair. e. The second pair. 
4 & 5. Front and side views of part of the trachea of the Gan- 
net (Pelicanus bassanus), having. two pair of muscles of - 
voice. d,d. The first pair, sterno-tracheal. e,e. The 
second pair. 
6 & 7. Front and side views of part of the trachea of the 
T Great Blue and Yellow Macaw (Psittacus Ararauna), 
CES having three pair of muscles of voice. d,d. The first 
~ pair. e,e. The second pair. f, f. The third pair. 
8. . Side: view of the same, the muscles partly detached for 
dis inction. - -Letters of reference the s samec 
