Radulopecten inequicostatus (Young & Bird, 1822)
YOUNG, G. & J. BIRD. 1822. A geological survey of the Yorkshire coast: describing the strata and fossils occurring between the Humber and the Tees, from the German ocean to the plain of York. 336 p., pls. 1-17. Printed at the Office of George Clark. Whitby, 1822. [p. 236, pl. 9, fig. 7]
1820 Pectinites articulatus Schlotheim 1820
1822 Pecten inequicostatus Young & Bird, 1822
1829 Pecten inaequicostatus Phillips, 1829
1836 Pecten octocostatus Roemer, 1836
1839 Pecten septemcostatus Roemer, 1839
1850 Pecten corallinus Orbigny, 1850
1852 Pecten biplex Buvignier, 1852
1862 Pecten semiplicatus Étallon in Thurmann & Étallon, 1862
1893 Pecten ursannensis Loriol, 1893
1895 Pecten neckeri Loriol, 1895
1822 Pecten inequicostatus Young & Bird, 1822
1829 Pecten inaequicostatus Phillips, 1829
1836 Pecten octocostatus Roemer, 1836
1839 Pecten septemcostatus Roemer, 1839
1850 Pecten corallinus Orbigny, 1850
1852 Pecten biplex Buvignier, 1852
1862 Pecten semiplicatus Étallon in Thurmann & Étallon, 1862
1893 Pecten ursannensis Loriol, 1893
1895 Pecten neckeri Loriol, 1895
«2. AMENDED DIAGNOSIS
Distinguished from all other species of Radulopecten by the inequality of the initial plicae.
3. AMENDED DESCRIPTION
Essentially very similar to R. vagans. Differing by the diagnostic feature (see Section 2); by the consistently early development of plicae, relatively invariant number of initial plicae (5-9; text fig. 211) and rarity of intercalary plicae; by the consistently wide spacing of the plical lamellae on the left valve and lack of lamellae on the right valve, even in large specimens (PI. 1 1, Fig. 9); by the greater convexity, thicker shell (PI. 11, Fig. 4) and more common attainment of a large size (see Section 7; Hmax : 75; MNP); by the ontogenetic decrease in H/L (text fig. 203) and by the marked ontogenetic increase in umbonal angle and larger mean H/UA (text fig. 204). Other metric proportions are plotted in text figs. 205-210.
Although the plicae are of unequal size in any individual the pattern of variation is relatively consistent between individuals,with the medial and antero-medial plicae usually the widest. 4. DISCUSSION
Most authors have applied PHILLIPS (1829) name inaequicostatus to the species described in Section 3. However, ARKELL (1935a) pointed out that YOUNG and BIRD (1822) described and figured an undoubted example of the species described in Section 3 under 'pecten' inequicostatus and that this name should therefore be the senior synonym. YOUNG and BIRD's specimen is without doubt lost so a neotype (BM
23173; PI. 11, Fig. 8) is herein designated.» 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. 219, 220]
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Radulopecten inequicostatus (Young and Bird 1822); A. L. A. Johnson, 1984, The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe, plate 11, figures 2, 4, 7-9.
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