Pseudopecten dentatus (J. de C. Sowerby, 1927)
SOWERBY, J. & J. DE C. SOWERBY. 1812-1846. The Mineral Conchology of
Great Britain; or coloured figures and descriptions of those remains of
testaceous animals or shells. 7 vols., pls. 1-648 (and 2 bis). London. [vol. 6, p. 143, pl. 574, fig. 1]
1927 Pecten dentatus J. de C. Sowerby, 1827
1863 Pecten thiollierei Martin, 1863
1864 Pecten euthymei Dumortier, 1864
1868 Pecten dieulafaiti Jaubert, 1868
1872 Pecten bersaskensis Tietze, 1872
1924 Pecten dobbertiensis Oertel, 1924
1863 Pecten thiollierei Martin, 1863
1864 Pecten euthymei Dumortier, 1864
1868 Pecten dieulafaiti Jaubert, 1868
1872 Pecten bersaskensis Tietze, 1872
1924 Pecten dobbertiensis Oertel, 1924
J. de C. Sowerby, 1927, plate 574.
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«SPEC. CHAR. Nearly orbicular, convex, minutely striated concentrically, ribbed; ribs about twenty close, large, angular, obtuse; ears defined, small; margin deeply toothed; valves similar.
THE peculiar characters of this Pecten are, the sharp projection of the edge between each rib and the flat inclined sides of each rib. Several specimens of this fossil are in the collection of Miss Baker, who found them in transported fragments of limestone, in what are there called gravel-pits, at Bugbrook and Staverton, in Northamptonshire. It also occurs in the valley of Catmus in Rutlandshire. The figure is taken from a specimen which has both valves, but wants the ears; they are supplied from another, in other respects inferior, individual.» JAMES DE CARLE SOWERBY, 1927
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«2. AMENDED DIAGNOSIS
«Distinguished from Ps. (Ps.) equivalvis by the higher, vertically striated, disc flanks (PI. 2, Fig. 13) and down-sulcal tongueing of the comarginal striae (Pl. 2, Figs. 11, 12). Distinguished from Ps. (Ps.) veyrasensis by the larger modal number of plicae (17/18 cf. 14).
3. AMENDED DESCRIPTION
Essentially similar to Ps. (Ps.) equivalvis apart from the diagnostic features (see Section 3), smaller maximum height 70 mm; DUBAR, 1925), greater convexity, acute angle between the anterior auricles and the hinge line, obtuse angle between the posterior auricles and the hinge line, and the ornament. Both valves ornamented with between 16 and 20 (most commonly 17 or 18) radial plicae (text fig. 62), rounded on the right valve, angular on the left. Usually one more plica on left valve than right; plicae occasionally bearing lamellae near the anterior and posterior margins.
Metric proportions are plotted in text figs. 60, 61. 4. DISCUSSION
The lectotype (herein designated) of 'Pecten' dentatus J. DE C. SOWERBY (BM 20719; PI. 2, Figs. 11, 12; 1) is a large, somewhat atypical, form with 20 plicae. It has moreover suffered post-mortem compression such that the characteristic features of high disc flanks and convexity are not apparent. However, the diagnostic ventral tongueing of the sulcal growth lines is visible and leaves no doubt that the specimen should be the name bearer for the species described in Section 3. 'P.' priscus SCHLOTHEIM; GOLDFUSS (non SCHLOTHEIM) also exhibits this feature while 'P. ' acutiradiatus MÜNSTER; DUMORTIER (non MÜNSTER) has the vertically striated disc flanks diagnostic of Ps. (Ps.) dentatus.»
JOHNSON, A. L. A. 1984. The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe. Zitteliana, 11: 1-235, pls. 1-11. [p. 74, 75]
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Pseudopecten (Pseudopecten) dentatus (J. de C. Sowerby 1827); A. L. A. Johnson, 1984, The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe, plate 2, figures 11-14.
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