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II.—Some Cretaceous Pycnodont Fishes

Published online by Cambridge University Press:  01 May 2009

Extract

The only important fragment of a Pycnodont fish hitherto known from the English Cretaceous Formations, is the portion of head and trunk figured and briefly noticed by Dixon under the name of Gyrodus angustus, Ag. This specimen displays the splenial bones from the oral aspect; some of the vertebral hæmapophyses; and thick scales with a reticulated ornament, covering only the anterior half of the trunk. The ventral ridge-scales also exhibit very conspicuous serrations. The splenial bones are imperfect, but sufficient to show all the essential characters of their oral face; and these elements present the only unique feature in the specimen. It will be observed that, whereas in all Pycnodont splenials hitherto described the dentition reaches the outer border at least in part of its extent, the bone in Gyrodus angustus has a wide toothless outer margin and an attenuated knife-like edge. The two vacuities in this margin shown in Dixon's figure are partly due to accident, partly imaginary, and there is no doubt that the bone forms a continuous whole.

Type
Original Articles
Copyright
Copyright © Cambridge University Press 1893

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References

page 487 note 1 Dixon, F., “Geology and Fossils of Sussex” (1850), p. 370, pl. xxxiii.Google Scholar fig. 1. See also Woodward, Smith, Proc. Geol. Assoc. vol. x. (1888), p. 307.Google Scholar

page 488 note 1 von Zittel, K. A., “Handbuch der Palæontologie,” vol. iii. (1887), p. 249.Google Scholar

page 488 note 2 Forir, H., “Contributions à l'Etude du système Crétacé de la Belgique,” Ann. Soc. Géol. Belg. vol. xiv. (1887), Mém. p. 25.Google Scholar Also Ibid. vol. xvi. Mém. p. 445.

page 490 note 1 Wagner, A., Abhandl. k. bay. Akad. Wiss., math.-phys. Cl., vol. ix. (1862), p. 326.Google Scholar Also von Zittel, K. A., “Handb. Palæont.” vol. iii. (1887), p. 239, fig. 251.Google Scholar

page 492 note 1 A. E. Reuss, “Versteinerangen der böhmischen Kreideformation” (1845), p. 10, pl. iv. figs. 15–25, 64.

page 492 note 2 H. B. Geinitz, Palæontogr. vol. xx. pt. i. (1875), p. 301, pl. lxv. figs. 31, 32.