1879.] 



TRACHEA OF THE GALLIN.E. 



371 



urogallus with T. tetrix on the other. Its cartilages are consider- 

 ably less yielding than those of either genus ; and the lower tracheal 

 rings, instead of fusing behind to form a continuous longitudinal bar 

 supporting the remaining parts of the rings upon each side, remain 

 separate, in close contact, for the posterior half of their circumfer- 

 ence. The pessulus interpolates its considerable cuneate posterior 

 end as high as the antepenultimate ring, which it splits up. The 

 lowermost nineteen tracheal rings are considerably thinned in front, 

 the uppermost being least so. Of these, the antepenultimate ring, 

 as well as the one above it, give indications of being bent downwards 

 in the middle line in front. This angulation is more marked in the 

 penultimate ring, and most so in the last ring, where a mid-anterior 

 rhombic cartilage exists, of exactly the same shape as in Lac/opus sco- 

 tieus. The first and second bronchial semirings agree precisely with 

 those of the last-named species, convexly upwards as they are curved ; 

 and, as in all the species of Lagopus and Tetrao, the bronchidesmus 

 is strong, at the same time that the bronchial semirings almost 

 completely encircle the tubes, leaving a very narrow membranous 

 unsupported wall. The bronchial tubes are comparatively lengthy. 



Fig. 22. 



Fig. 23. 



Front view. 



Perdix cinerea. 



Back view. 



In Perdix cinerea the intrathoracic portion of the trachea is quite 

 different from the same in Caccabis or any of the birds above de- 

 scribed. The last and penultimate tracheal rings are much deve- 

 loped, and blend to form the considerable three-way piece, which is 

 triangular in front, apex downwards, and horizontally oblong behind. 

 Of the anterior triangle, which is ossified, the two sides are formed 

 by the last ring, whilst the penultimate ring constitutes the base, the 

 intervening interval being filled up with a thin cartilage. The apex 

 of the triangle is continued downwards in cartilage, this latter being 

 deeply notched in the middle line, at the same time that the anterior 

 extremities of the first and second slender and upward-arched bron- 



24* 



