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V.—Note on Plectrodus, the Jaw of an Upper Silurian Fish

Published online by Cambridge University Press:  01 May 2009

Extract

When fish-remains were first discovered in the Ludlow bone-bed and other horizons of the Upper Silurian series, some of the fragments were regarded as toothed jaws by Agassiz, who described them under the names of Plectrodus mirabilis, P. pleiopristis, and Sclerodus pustuliferus. The same fossils were afterwards considered to be of Crustacean origin by M'Coy, but definitely proved to be fish-remains by the microscopical examination of Harley, who pointed out that while they could not be teeth or jaws, they appeared to him to be “the posterior spines of the cephalic plate of some Cephalaspidian fish”. The latter view was adopted by Lankester, who treated the specimens as parts of the cornua of a small Cephalaspidian headshield which he named Eukeraspis pustuliferus.

Type
Original Articles
Copyright
Copyright © Cambridge University Press 1917

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References

1 Agassiz, L., in Murchison's Siluria, 1839, p. 606, pl. iv, figs. 14–32, 60–2.Google Scholar

2 Pterygotus pustuliferus, M'Coy, F., Quart. Journ. Geol. Soc., vol. ix, p. 14, 1853.Google Scholar

3 Harley, J., “On the Ludlow Bone-Bed and its Crustacean Remains”: Quart. Journ. Geol. Soc., vol. xvii, p. 544, 1861.Google Scholar

4 Lankester, E. Ray, Fishes of the Old Red Sandstone, pt. i (Pal. Soc., 1870), p. 58, pl. xiii, figs. 9–14.Google Scholar

5 Egerton, P. M. G., “On some Fish-remains from the Neighbourhood of Ludlow”: Quart. Journ. Geol. Soc., vol. xiii, p. 288, pl. x, figs. 2–4, 1857.Google Scholar

6 Woodward, A. S., Catalogue of Fossil Fishes in the British Museum, pt. ii, 1891, p. 195.Google Scholar

7 Rohon, J. V., “Die Obersilurischen Fische von Oesel”: Mém. Acad. Imp. Sci. St. Pétersbourg 7, vol. xli, No. 5, p. 95, 1893.Google Scholar