. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ch. XXVI.] OLD RED SAXDSTOXE. 533 several species now inhabiting the Xile and other African rivers. The reader will at once recognize in Osteolepis (fig. 599) one of the coin Ksr. Eestoration of Osteolepis. Pander. Old Red Sandstone, or Devonian. a. One of the fringed pectoral fins. b. One of the ventral fins. e. Anal fin. d, e. Dorsal fins. mon fishes of the Old Red Sandstone, many points of analogy with Pohjpterus. They not only agree in the structure of the
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ch. XXVI.] OLD RED SAXDSTOXE. 533 several species now inhabiting the Xile and other African rivers. The reader will at once recognize in Osteolepis (fig. 599) one of the coin Ksr. Eestoration of Osteolepis. Pander. Old Red Sandstone, or Devonian. a. One of the fringed pectoral fins. b. One of the ventral fins. e. Anal fin. d, e. Dorsal fins. mon fishes of the Old Red Sandstone, many points of analogy with Pohjpterus. They not only agree in the structure of the fin, as first pointed out by Huxley, but also in the position of the pectoral, ventral, and anal fins, and in having an elongated body and rhomboidal scales. On the other nand, the tail is more symmetrical in the recent fish, which has also an apparatus of dorsal finlets of a very abnormal char- acter, both as to number and structure. As to the dorsals of Osteolepis, they are regular in structure and position, having nothing remarkable about them, except that there are two of them, which is comparatively nnusual in living fish. Among: the " fringe-finned " Ganoids we find some with rhomboidal scales, such as Osteolepis, above figured, and Diplopterus, Glyptolcemus, and Glyptopomus ; others with cycloidal scales, as Holoptychius (see fig. 588, p. 525), Dipterus, &c. The new genus Glyptolcemus, founded by Huxley on specimens from the Devonian yellow sandstone of Dura Den in Fife, is remarkable for having not only a fringe of rays entirely surrounding a central lobe in the pectoral and ventral fins, but in hav- ing the same structure repeated in the anal and both the dorsal fins. In the genera Dipterus and Diplopterus, as Hugh Miller pointed out, and in several other of the fringe-finned genera, as in Gyroptycliius and Glytolepis, the two dorsals are placed far backwards, or directly over the ventral and anal fins. The Asterolepis was a ganoid fish of gigantic dimens
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1868
