ON THE TRACHEA IN THE " RATITE " BIRDS. 239 



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

 backwards. The cartilaginous tracheal rings are complete behind, and 



Fig. 7. 



Bifurcating trachea of Ehea americana, from before. 

 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 Casuarius, is also represented. 



closely approximated to each other. The last four tracheal rings are 



soldered together to form a cartilaginous box, the constituents of which 



are marked out by the interannular sutures, which are only interrupted in 



the middle line anteriorly and posteriorly. The exact number of tracheal P. Z. S. 1881, 



rings which are fused to form this box varies in different specimens from p * 786> 



