A treatise on zoology . the lower Teleostomes; the lumen may becomereduced or disappear, and the air-bladder be quite cut off in theadult from the alimentary canal—a fact which led authors to dividethe Teleostei into Physostomi with open, and Physoclisti with closedpneumatic duct. The shape of the air-bladder undergoes all sorts of modifications:in the Cyprinidae it is constricted into a small anteiior and a larger 360 TELEOSTEI posterior chaml)er ; in OtuUthus a median chamber has paired hiteralprolongations (Fig, 349); in the Sciaenidae and Polyxenidae in-numerable branching diverticula are
A treatise on zoology . the lower Teleostomes; the lumen may becomereduced or disappear, and the air-bladder be quite cut off in theadult from the alimentary canal—a fact which led authors to dividethe Teleostei into Physostomi with open, and Physoclisti with closedpneumatic duct. The shape of the air-bladder undergoes all sorts of modifications:in the Cyprinidae it is constricted into a small anteiior and a larger 360 TELEOSTEI posterior chaml)er ; in OtuUthus a median chamber has paired hiteralprolongations (Fig, 349); in the Sciaenidae and Polyxenidae in-numerable branching diverticula are given off (Fig. 348) ; inCalllchthys the complication is still greater. The cavity of the air-bladder is sometimes divided into compartments (Siluridae (p. 377)),or small alveoli {Erythrinus). In the Herring (Fig. 383) a specialopening to the exterior is formed behind the anus (Weber) ; whilea communication is established with the right branchial cavity inthe physoclistous Caranx trachiurns (Moreau). Tlie bladder is a. Fig. 346. A aud B, fiye of Acanfhias vulgaris, Risso. B and C, eye oiScdmo salar, L. A and C, sectionof eye vertical to .surface, leaving the lens intact. B and D, inner view of the enter half of theeyeball, showing the lens in position. 1, lens ; 2, cut surface of retina; 3, retina : 4, anteriorchamber or aqueous luiniour; 5, posterior chamber or vitreous humour; li, pigment layer; 7,cut edge of sclerotic; 8, iris; 0, ora serrata ; 10, optic nerve; 11, cornea; 12, ventral accom-modating muscle (ciliary process); 13, vascular ridge from choroid fissure ; 14, vascular process(campanula Halleri). (Goodrich and Gradon.) hydrostatic organ, is never supplied direct from the aortic arches(p. 226), and never functions quite as a lung; but on its inner wallare developed retia mirabilia, highly vascular patches, which secretethe gases in thf l)lad(ler (Basse [199]). Caecal outgrowths towards the head and tail occur in a largenumber of families (Berycidae, Siluridae, Clu
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
