. A manual of zoology. Zoology. /I'. VKllTEVIiATA: PISCES. :,Cu. Fig. o'.tr).âSc'OtioTis of u'iU arches i)f Liiliht.^ (Ifft) and Ziiiji'-iin (rit,')it), slit;litly enlarged, n, artei-y ; '', gill areh ; hi', hi-, deinibraiiolis; //, dermal ; /â , cartilage ray; r, \'ein : z, toutli. (j7jr) from the byoid, these latter svipiiortiiig the bnuiehiostega] niembvaiie. ]>et\veen the free edge of the (jjiercuhini and the mem- brane and tlie skii^i of tlie body Ijehiud tlie opereular cleft (fig. 5'.)-l, opy), ^vhi(:â h h obviously not identical with a gill cleft, but
. A manual of zoology. Zoology. /I'. VKllTEVIiATA: PISCES. :,Cu. Fig. o'.tr).âSc'OtioTis of u'iU arches i)f Liiliht.^ (Ifft) and Ziiiji'-iin (rit,')it), slit;litly enlarged, n, artei-y ; '', gill areh ; hi', hi-, deinibraiiolis; //, dermal ; /â , cartilage ray; r, \'ein : z, toutli. (j7jr) from the byoid, these latter svipiiortiiig the bnuiehiostega] niembvaiie. ]>et\veen the free edge of the (jjiercuhini and the mem- brane and tlie skii^i of tlie body Ijehiud tlie opereular cleft (fig. 5'.)-l, opy), ^vhi(:â h h obviously not identical with a gill cleft, but leads into an atrinm into "which tlie gill clefts empty. In many elasmobraiichs and ganoids there is a rudimentary cleft, the spiracle, between the pterygoquadrate and hyomandibular, in v\hich a rudimentary gill, or pseudobranch, may occur, this often j'cr- sisting when the spiracle is (dosed. Besides gills, fishes, ^\]t]\ the exception of elasmobraiichs and some teleosts, have a swim bladder which is usually regarded as the homologue of the lungs. It is often shaped like an hour glass, filled with air, and may open into the O'soplnigus liy a pneuniatie duct (Physostomi), or this, appearing in de\elo})ment, may be lost in the adult (Pliysoclisti). 'J'lie air bladder serves fur respiration in the Dipnoi and possibly in some ganoids {Lcjiidoslnis and Amla), but is usually a hydnistatie ap})aratus, its enlargement or compression altering the specific gravity of the fish. In fishes brotight uj) from great depths the e.\j) of air in tlie swim bhidder frequently forces the viscera. (Hit thi'duali the mouth. 1'he heart, encloseil in the jierienrdiuni, lies immediately behind the gill region, and is }ir(ilc<'ted by the shoulder girdle. It always consists of auricle and \'eiitricle (fig. â¢")'.»<;), se})arated by a. jiair of valves to prevent liaeb-llow of the bhiod; it sends the Idood to the gills by the arterial tniid< (ventral aorta), and receives i
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
