OCR Text |
Show 1879.] TRACHEA OF THE GALLINAE. 371 urogallus with T. tetrix on the other. Its cartilages are considerably 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 circumference. 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 Lagopus scoticus. 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 bronehidesmus 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. Back view. Perdix cinerea. InPerdix cinerea the intrathoracic portion of the trachea is quite different from tbe same in Caccabis or any of the birds above described. The last and penultimate tracheal rings are much developed, 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- |