OCR Text |
Show 1879.] TRACHEA OF THE GALLINAE. 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 fusiform 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 delicate. Posteriorly, however, its ends develop into large fairly equilateral 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. Back view. Lagopus scoticus. 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 consideration are built up of a m u c h more yielding cartilage (without ossifying 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- |