1879.] 



TRACHEA OF THE GALLING. 



367 



Lagopus scoticus is not far different from Thaumalea in certain 

 respects. The lower intrathoracic rings of the trachea are but little 

 modified above the antepenultimate, there being slight median fusi- 

 form anterior interannular intervals, whilst posteriorly the ununited 

 rings are keyed together, as in the middle of the windpipe generally. 

 The penultimate ring agrees with the same in Thaumalea, even to 

 being incomplete behind, the free ends slightly receding from the 

 ring above. The last ring anteriorly agrees with the same genus in 

 detail, its lateral arched moieties being even more slender and deli- 

 cate. Posteriorly, however, its ends develop into large fairly equi- 

 lateral triangular expansions, continuous with the slender lateral arch 

 at its supero-external angle, articulating with the posterior end of 

 the first bronchial semiring at its inferior angle, whilst its supero- 



Fig. 17. 



Fig. 18. 



Front view. 



Lagopus scoticus. 



Back view. 



internal angle joins a similar development at the side of the pessulus, 

 the hinder part of which expands into a sagittate cartilage, the blunted 

 apex of which is directed upwards to meet the middle of the inferior 

 margin of the antepenultimate ring of the trachea. The main bar 

 of the pessulus is very slender ; and all the structures under consider- 

 ation are built up of a much more yielding cartilage (without ossi- 

 fying tendencies) than in any non-tetraonine birds. The first and 

 second bronchial semirings are parallel to one another in course 

 throughout, and are more uptilted laterally than in Thaumalea. Pos- 



