1879.] 



TRACHEA OF THE GALLING. 



3G9 



tively great depth of the intervals between the lateral parts of the 

 last tracheal and the first bronchial semiring, observed in Thaumalea 

 for instance, not being seen. The first and second bronchial semi- 

 rings themselves, agreeing as they do with those of Lagopus in all 

 respects, are of the same thickness as their neighbours both above 

 and below — the result being simplicity of construction a little more 

 apparent than real. Many of the bronchial semirings are bifid at 

 their anterior extremities. 



In the male of Tetrao tetrix the trachea is most extraordinary. 

 At first sight the deeply situated intrathoracic part appears to have 



Fie. 19. 



Front view. 

 Tetrao tetrix, S • 



no similarity with that of the female, there being developed, on each 

 side, an immense irregular tumefaction, communicating with its 

 fellow by means of a bridge of fatty tissue which covers the anterior 

 portions of the lowermost tracheal rings. When preserved in spirit 

 this tumefaction shrinks to a comparatively small size, to swell to its 

 original bulk upon immersion in water. This leads me to suppose 

 that it is composed of " mucous " tissue, like that of the umbilical 

 Proc. Zool. Soc— 1879, No. XXIV. 24 



