J88I.] 



TRACHEA IN THE 



RATITE 



BIRDS. 



785 



In Rhea americana (figs. 7, 8) the average diameter of the trachea 

 interiorly is about 1 inch, and it is somewhat compressed from before 

 backwards. The cartilaginous traclieal rings are complete behind. 



Bifurcating traohea of Bhea americana, from bei'ore. 

 Fig. 8. 



The same, from behind. About the natural size. The intrinsic muscle has 

 been removed on the right side. In fig. 8 the fibrous band running down 

 the middle of the trachea posteriorly, as described above in Casuanus, is 

 also represented. 



and closely approximated to each other. The last four tracheal 

 rings are soldered together to form a cartilaginous box, the con- 

 stituents of which are marked out by the interannular sutures, which 

 are only interrupted in the middle line anteriorly and posteriorly. 



