1881.] 



TRACHEA IN THE " RATITE " BIRDS. 



779 



Struthio camelus (figs. 1, 2), on account of its size and simple 

 structure, may be described here first. The trachea, inferior to the 



Fig. 1. 



Bifurcating trachea of Struthio camelus, from before. 



b. Section of wall of trachea, from behind, to show the vocal cord formed 

 by the thickening of the mucous membrane of the interior. I. II., first two 

 bronchial semirings. 1, 2, &c., last tracheal rings. 



Here, and elsewhere in these figures, o indicates the last, oo the penultimate, 

 000 the antepenultimate tracheal rings. 



Fig. 2. 



Tlie same, from behind. About natural size. 



insertion of the sterno-tracheales, slightly narrows, having above the 

 antepenultimate ring a diameter of about one inch. 'J'he tracheal 



50* 



