. The structure and classification of birds . Pig. 43.—^Syrijjx or Struthio. 0, last, 00, penultimate, ooo antepenultimate tracheal rings ; &, section of wall of wind-pipe to allow vocal chord; 1-7, tracheal, I, II, bronchial rings. (After Forbes.) by dense fibrous and elastic tissue. There is no trace of apessulus, though the last tracheal ring is slightly produced. Fig. 44.—The same Sybinx ibom Behind. downwards in front. The first bronchial semi-ring on eachside is narrow and cylindrical, strongest anteriorly, andsomewhat attenuated posteriorly. It is separated only by a RESPIRATORY SYSTEM
. The structure and classification of birds . Pig. 43.—^Syrijjx or Struthio. 0, last, 00, penultimate, ooo antepenultimate tracheal rings ; &, section of wall of wind-pipe to allow vocal chord; 1-7, tracheal, I, II, bronchial rings. (After Forbes.) by dense fibrous and elastic tissue. There is no trace of apessulus, though the last tracheal ring is slightly produced. Fig. 44.—The same Sybinx ibom Behind. downwards in front. The first bronchial semi-ring on eachside is narrow and cylindrical, strongest anteriorly, andsomewhat attenuated posteriorly. It is separated only by a RESPIRATORY SYSTEM 65 narrow interval from the last tracheal ring. The second andthird rings are similar, but are more slender and lengthy;they are convex downwards, but very slightly so; hence theinterannular intervals are slight here also. Their anteriorends are very slight, inturned, impinging but to a smallextent on the membrana tympaniformis, which completesthe bronchial tubes internally, and, in consequence of theabsence of any three-way piece, passes continuously fromone bronchus to another, so closing the tracheal tube in-feriorly. The fourth, fifth, and succeeding bronchial ringsare similar in character, but their ends, which tend to bedilated posteriorly, are successively more and more incurvedto about the tenth. Nowhere are the bronchial rings com-plete. There is a
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1898
