. The Cambridge natural history. Zoology. CHAPTEE XI THE AIR-BLADDER In the Crossopterygii, Chondrostei, and Holostei, in the Dipnoi, and in the great majority of Teleosts, there is situated on the dorsal side of the coelom, between the alimentary canal below and the kidneys and vertebral column above, a more or less elong- ated sac with membranous walls, an internal epithelial lining and gase- ous contents—^the air-bladder (Figs. 154 and 173). Usually developed in the embryo as a caecal outgrowth from the dorsal surface of the oesophagus, the air-bladder grows anteriorly and posteriorly, and
. The Cambridge natural history. Zoology. CHAPTEE XI THE AIR-BLADDER In the Crossopterygii, Chondrostei, and Holostei, in the Dipnoi, and in the great majority of Teleosts, there is situated on the dorsal side of the coelom, between the alimentary canal below and the kidneys and vertebral column above, a more or less elong- ated sac with membranous walls, an internal epithelial lining and gase- ous contents—^the air-bladder (Figs. 154 and 173). Usually developed in the embryo as a caecal outgrowth from the dorsal surface of the oesophagus, the air-bladder grows anteriorly and posteriorly, and may either retain throughout life its primitive connexion with the alimentary canal by means of a longer or shorter tubular canal, the ^^^_ section of the ductus pneumaticus, or become completely separated therefrom in the adult by the atrophy of the duct. Its walls sometimes, but rarely, contain muscle-fibres, as in Zepidosteus, Amia, and the Dipnoi, and are always more or less vascular, while laterally and ventrally the organ is invested externally by the peritoneum (Fig. 173). In addition to the muscle-fibres distributed in its walls, the bladder is often provided with powerful extrinsic muscles, more especially in those Fishes in which it is used as an organ for sound-. vp body of a Teleost, to show the position of the air-bladder (dia- grammatic). , The air-bladder ; c, coelom ; d,p^ ductus pneuma- ticus ; k, the kidneys ; oes, oeso- phagus ; and , parietal and visceral layers of the peritoneum ; r, rib ; ^.c, vertebral column. 297. 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 Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
