Pernopecten ohioensis Newell, 1938
NEWELL, N. D. 1938. Late Paleozoic Pelecypods: Pectinacea. State Geological Survey of Kansas, 10: 1-123, pls. 1-20. [p. 112, pl. 20, figs. 1-3, 5, 6]
1938 Pernopecten ohioensis Newell, 1938
N. D. Newell, 1938, plate 20.
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«Entolium aviculatum, HERRICK, 1887, Denison Univ. Sci. Lab., Bull., vol. 2, p. 23, pI. 1, figs. 1, 2; pI. 3, fig. 10.
——, MORNINGSTAR, 1922, Ohio Geol. Survey, Bull. 25, p. 232, pI. 13, fig. 9. In our collections there are two similar pernopectens, distinguished from each other by a marked difference in size and by pecularities of the right valve. The available material appears to be sufficiently complete to indicate that the larger of the two forms, P. clypeatus, n. sp., is found only in beds of Missouri and Virgil age, whereas the small form P. ohioensis, n. sp., is found only in the Des Moines subseries or equivalent rocks. The size difference may be due partly to ecological factors, because the Des Moines specimens that I have seen occur chiefly in carboniferous limestone, whereas the post-Des Moines specimens are found chiefly in pure or argillaceous limestone. Right valves of this species are extraordinary in winglike lobes or projections
at the front and rear margins. I am at loss to account for this discrepancy between right and left valves (see fig. 42) except on the assumption that the two valves did not fit snugly together along the ventral margin. There is a real stratigraphic distinction between the two forms, and this fact justifies the application of different names to them. The suite of specimens is from the lower Mercer limestone, Flint Ridge, Licking county, Ohio. Measurements of specimens of Pernopecten ohioensis are given in the table on page 110.
Comparison.— As indicated in the description, the small size and peculiar form of the right valves distinguish this species. The largest Pernopecten that I have seen from beds of Des Moines age is scarcely half as large as a full-grown P. prosseri or P. clypeatus.
Material.— The species is based on 21 specimens, right and left valves, from a single horizon and general locality. The holotype and several topoparatypes are U. S. Nat. Mus., No. 89,789. There are several topoparatypes at the University of Kansas, and two at Ohio State University, No. 4,604. In these specimens the inner ostracum has not been preserved, but the outer ostracum in both valves shows the original structure. There are in addition several other specimens from various localities. Found in black and dark-gray carbonaceous limestone.
Occurrence.— Upper Carboniferous. The holotype and topoparatypes came from the lower Mercer limestone, Flint Ridge, Licking county, Ohio; other paratypes are from the Liverpool formation, SW ¼ sec. 15, Knox Township, Knox county, Illinois; "Coal Measures" (probably Cherokee) Henry county, Missouri; Boggy shale, NW ¼ sec. 27, T. 3 N., R. 7 E., Okla.»
NORMAN DENNIS NEWELL, 1938
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«De Pernopecten ohioensis NEWELL, 1937 (Newell, p. 112, pl. 20, fig. 1-3, 5, 6; Hoare, 1961, p. 116, pl. 15, fig. 15, 16), nos exemplaires diffèrent par un contour proportionnellement plus élevé.»
BABIN, C. & J.-J. DELVOLVÉ. 1982. Une faune de Mollusques bivalves du Namurien des Pyrénées centrales francaises. Geobios, 15 (5): 729-753, pls. 1, 2. [p. 743]
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