. Outlines of zoology. Fig. 304.—Larva of Polypterus (after Budgett), iJ inch in length. , Large external gill of the hyoid arch; Pc., pectoral fins; Pv., pelvicfins. The larva is drawn in a very characteristic attitude. The following three orders are often grouped as Actino-pterygii, with the following characters. The paired fins arenever lobate, they have short basal pieces, and are mainlysupported by dermal fin-rays. Order 2. Chondrostei—with cartilaginousinternal skeleton Living examples:—Sturgeon (Acipenser), Polyodon, Fig. 305.—Sturgeon [Acifenser siurio).Note the e
. Outlines of zoology. Fig. 304.—Larva of Polypterus (after Budgett), iJ inch in length. , Large external gill of the hyoid arch; Pc., pectoral fins; Pv., pelvicfins. The larva is drawn in a very characteristic attitude. The following three orders are often grouped as Actino-pterygii, with the following characters. The paired fins arenever lobate, they have short basal pieces, and are mainlysupported by dermal fin-rays. Order 2. Chondrostei—with cartilaginousinternal skeleton Living examples:—Sturgeon (Acipenser), Polyodon, Fig. 305.—Sturgeon [Acifenser siurio).Note the elongated snoutj the barbules bounding the ventral mouth,the operculum covering the gills, the rows of bony scutes, themarkedly heterocercal tail. Extinct examples;— Cheirolepis, Palceoniscus, Chondrosteus. In the sturgeon {Acipenser) the skin bears five rows of large bonyscutes; the tail is heterocercal; the notochord is unsegmented. Asnout, with pendent barbules, extends in front of the ventral mouth,which is rounded and toothless. Sturgeons feed on other fishes. TELEOSTEI. 571 which they swallow whole. They are the largest fresh-water fishes,for A. sturio may attain a length of 18 ft. and a weight of 600 lb.,while the A. huso of Southern Russia may measure 25 ft. and weighnearly 3000 lb. ! Most of the species are found both in the sea and inrivers or lakes. The roes or ovaries form caviare; the gelatinousinternal layer of the swim-bladder is used as isinglass. The genus Scaphirhynckus is represented in Asia and the UnitedStates; Po
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
