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Show 374 PROF. A. H. GARROD ON THE [Apr. 1, but anteriorly they are thinner, leaving considerable intervals, diminishing as they ascend-continuous between the five rings above the penultimate, found also between it and the last, but in that case interrupted by a small median connecting isthmus, which is broader below than above, at the same time that it is continuous with the superiorly broader medio-anterior descending process of the last ring, the two together forming a lozenge-shaped cartilage that receives the extremities of the first semirings at its lower margin. Posteriorly the pessulus is continuous with the penultimate ring, whilst the ends of tbe last tracheal also blend with it slightly. The second bronchial semiring is slightly larger than the first, and articulates with it in the usual way, as does the first with the last tracheal ring. There is a great uniformity in the depths of all the interannular intervals in the region of the bifurcation of the trachea. Fig. 26. Fig. 27. Front view. Crossoptilon mantchuricum. Back view. In Numida cristata, which m a y be taken as the type of the very characteristic windpipe of the genus, figured accurately as it is in part by Temminck', the peculiarity is that the lowermost six or so tracheal rings develop antero-lateral fenestrae between them, increasing m size from above downwards, and produced by the thinning 1 Loc. cit. pi. i. fig. 4. |