108 The Convolution of the Trachea in the | [February, 
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10: 
THE CONVOLUTION OF THE TRACHEA IN THE 
SANDHILL AND WHOOPING CRANES. 
BY THOMAS S. ROBERTS. 
T is well known to ornithologists, that in many birds there are 
various peculiar modifications of'the trachea, or windpipe, 
which, it is supposed, serve the purpose of adding some particu- 
lar quality to the voice. Passing by the numerous minor instan- 
ces of this structure as seen frequently in ducks, in some geese 
and a few other birds, we find it most strikingly exhibited among 
the cranesand swans. In certain species of these two groups the _ 
trachea enters the enlarged and excavated keel of the sternum, 4 
and after a number of convolutions, varying in position and ex- _ 
tent with the species, passes out at the place of entrance and thence 
intothe lungs. In such cases, at least, it is plainly great strength _ 
-and volume of tone which are imparted, as is clearly evidenced — 
by the powerful utterances for VERA these birds are noted, 
