. Notes on the North American ganoids [microform] : Amia, Lepidosteus, Acipenser, and Polyodon, with three plates. Ganoidei; Fishes; Ganoide; Poissons. I >."â¢-. ,^ J â B. NATUUAI, iiisTonr. 163 â¢n of the upper camJul 'f Fianquo (lo) and »c adult Amia rcsem- 3ul inferring that it ^tions. AndlwoulU places of Amia, the ' <lf velopment. loid nature being in gy will be especially isses are comparable I fossil forms. '⢠in legard to more tlie direction of the iai median fin. esented among the may infer that the has a continuous liickness^ and with tliat the posterior fleeted downward,
. Notes on the North American ganoids [microform] : Amia, Lepidosteus, Acipenser, and Polyodon, with three plates. Ganoidei; Fishes; Ganoide; Poissons. I >."â¢-. ,^ J â B. NATUUAI, iiisTonr. 163 â¢n of the upper camJul 'f Fianquo (lo) and »c adult Amia rcsem- 3ul inferring that it ^tions. AndlwoulU places of Amia, the ' <lf velopment. loid nature being in gy will be especially isses are comparable I fossil forms. '⢠in legard to more tlie direction of the iai median fin. esented among the may infer that the has a continuous liickness^ and with tliat the posterior fleeted downward, 3wer caudal lobes.' tl»e spinal axis is jns of subdivision, mocercal by most nd as protocercal reneral subject of hat all the argu- homocercal'o as ith even greater For the latter ion exists in the »s and Ganoids; But he applies this . the aiTmifrement ig whole subject, liow- development of the In certain very nnclenl Ganoids (as Ghjptolo'mus and GurnptijchiuH) ; and in tJie generalized forms Lppldosiren and Ceratodua. 1 have not been al)le, however, .to find tlie word used clsewhcro than in Wyman's paper on the Development of Jtaki hutii* (11). Upon the general subject see Huxley (6, 7, and 15), with other papers therein referred to. This stage of tiie Lepidonteus may be compared with Amphioxua, the lowest known Vertebrate, with Lepidosiren, Protopterus and feratoc/KS,!' where, however, the primordial ttn-rays seem to imve been replaced by stronger and permanent rays ; Myxine, Bdellos- toma and Petromyzon, where the rays are cartilaginous ;'â » (in some species of Petromyzon the median Hn is continuous, with slight undulations indicating the subdivisions in other species) ; and with Membranchvs and Menopoma, where, as in the larvae of Anoura, there are no fln-rays at all. The cartilaginous prolongation of the vertebral colump of Polyp- tents is not shown by Agassiz (5,11, tab. C). It is figured by Huxley and described (7, 20), as hardly at all bent up. In a
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectfishes, bookyear1876
