Pernopecten clypeatus Newell, 1938
NEWELL, N. D. 1938. Late Paleozoic Pelecypods: Pectinacea. State Geological Survey of Kansas, 10: 1-123, pls. 1-20. [p. 112, pl. 1, figs. 1, 14, 15; pl. 2, figs. 7-11]
1938 Pernopecten clypeatus Newell, 1938
N. D. Newell, 1938, plates 1, 20.
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«?Pecten aviculatus SWALLOW, 1858, St. Louis Acad. Sci., Trans., vol. 1, p. 213 (not Pecten aviculalus G. von Münster, 1832).
Relatively large, distinctly prosocline, closely similar to Pernopecten prosseri (Mark), but especially distinguished by the development of an emargination or crest behind the rear auricle of the left valve, by which the shell body is extended dorso-posteriorly in a rounded convex margin behind the posterior auricle.
Measurements of specimens of P. clypeatus are given in the table on page 110. Comparison.— This form is especially distinguished by its robust size, and by the distinctive posterior profile.
Material.— Six nearly complete specimens and several fragmentary ones from Wabaunsee beds near Thurman, Iowa (Yale Univ., Peabody Mus., Nos. 14,485, 14,486). Found in argillaceous gray limestone.
Occurrence.— Upper Carboniferous. Missouri and Virgil subseries. The types came from the Howard limestone (Wabaunsee group), 2 miles north of Thurman, Iowa, and the Wakarusa limestone (Wabaunsee), south of the fault at Thurman, Iowa. There is one specimen from the Captain Creek limestone (Lansing group) near Olathe, Kan.; several specimens from an unidentified horizon in the upper Shawnee group, near Topeka, Kan.; Soldier Creek shale CWabaunsee), one half mile west of the mouth of Walnut Creek, Kebraska City, Neb.; Wakarusa limestone (Wabaunsee), Table Rock clay pit, Table Rock, Neb.; Kereford limestone (Shawnee), Snyderville, Neb.»
NORMAN DENNIS NEWELL, 1938
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