CHAPTER VII 
THE RESPIRATORY ORGANS 
The Larynx and Trachea. In the Crocodilia 
the framework of the larynx consists of three 
cartilages, of which two represent the arytenoids 
of the Mammalia; the third represents the thyroid 
and cricoid of mammals. The last is considerably 
larger than the first and is a broad closed ring, dif- 
fering in form in the different species. In spite of 
the fact tnat some of them have a voice, the vocal 
cords, according to Bronn, are wanting in the 
Crocodilia. According to Henle the vocal appara- 
tus is produced by the projection into the laryngeal 
cavity of the inner border of the small arytenoid 
cartilages and by the infolding, under these carti- 
lages, of the mucous membrane of the larynx; this 
forms the thick but fairly free folds that, when the 
glottis is narrowed, are well adapted to produce 
the harsh tone of the animal. 
The epiglottis is absent in the Crocodilia. 
In many Crocodilia (C. vulgaris, for example) 
the trachea, Fig. 57, tr, forms a loop which begins 
in some species before hatching, in other species not 
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