. The biology of birds. Birds. ECONOMY OF THE BODY 125 tympanum. It is again of biological interest to notice that wiiile the syrinx is a new structure, and pecuUar to birds, it is in reahty a transformation and compHcation of the base of the trachea and the beginning of the bronchial tubes. The main chamber, as we have mentioned, is called the tympanum. It is traversed horizontally by a projecting bony band called the pessulus, and this forms a partition Fig. 31.—Syrinx of raven (after Oven), i. Side view laid open; PE., the bony band or pessulus ; , membrana semilunaris, a fol
. The biology of birds. Birds. ECONOMY OF THE BODY 125 tympanum. It is again of biological interest to notice that wiiile the syrinx is a new structure, and pecuUar to birds, it is in reahty a transformation and compHcation of the base of the trachea and the beginning of the bronchial tubes. The main chamber, as we have mentioned, is called the tympanum. It is traversed horizontally by a projecting bony band called the pessulus, and this forms a partition Fig. 31.—Syrinx of raven (after Oven), i. Side view laid open; PE., the bony band or pessulus ; , membrana semilunaris, a fold supported on the pessulus; , membrana tympaniformis interna, the internal wall of a bronchus. 2. Syrinx after removal of muscles ; , last modified tracheal ring; , three first modified bronchial rings. 3. Front view of syrinx with muscles (m.), and sternotracheal muscles (), extending from the trachea to the sternum ; , membrana tympaniformis interna. between the anterior openings of the two bronchial tubes. It gives off on each side two arched processes, dorsal and ventral, which run down the bronchial tube. Between these two horn-like processes the membranous wall of the bronchial tube is stretched, forming the membrana tym- paniformis interna. In singing birds there is another membrane, the semilunar, attached to the pessulus, and there may be another on each side of the glottis. These. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Thomson, J. Arthur (John Arthur), 1861-1933. New York : Macmillan
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Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbirds, bookyear1923
