184 SOME POINTS IN THE ANATOMY OF STEATORNIS. 
as that of the combined organ in most of the non-singing birds. 
Taking for description that of the left side in the specimen figured, it — 
is there found that the thirteenth bronchial ring is complete, though 
Front view of the syrinx of Steatornis. 
considerably flattened from side to side; the fourteenth is not com- 
plete in the middle of its inner surface, it is a little longer from before 
backwards than the one above, and not so long as the one following it. 
The fifteenth is only a half ring, its inner portion being deficient; it is 
slightly convex upwards, and articulates, both at its anterior and pos- 
terior ends, with the fourteenth incomplete ring and the sixteenth half 
ring. The sixteenth half ring is coneave upwards, and so forms an 
oval figure in combination with the one above, which is filled with a 
thin membrane, to form part of the outer wall of the bronchus. 
There is a membrane also between the ends of these and the succeed- 
ing half rings, which completes the tube of the bronchus internally. 
The half rings which follow the sixteenth reduce in size, and are con- 
siderably smaller before they reach the lung. The lateral muscle of 
the trachea extends down the outer side of each bronchus, to be 
Page 533. attached to the middle of the first fully developed half ring. The 
depressor muscles of the trachea are independent of these. 
