Placopecten osawanoensis (Tsuda, 1959)
TSUDA, K. 1959. New Miocene Mollusca from the Kurosedani Formation in Toyama Prefecture, Japan. Journal of the Faculty of Science, Niigata University [Series II, Biology, Geology and Mineralogy], 3 (2): 67-110, pls. 1-7. [p. 72, pl. 1, fig. 10]
1959 Pecten (Placopecten) osawanoensis Tsuda, 1959
«Holotype : — GK, Reg. No. JC 1400010.
Remarks: — This species can be distinguished from Placopecten protomollitus (Nomura) by the rather smaller shell, fewer and rather more distinct radial ribs, finely imbricated intercalary threads, subequal auricles in the right valve and by the left valve having the rather elevated radial ribs usually accompanied with a single intercalary thread. The present species was originally described by Tsuda based upon a single left valve. Type locality, Geologicalformation and Age: — Left cliff of the Dô River, Tsuzara, Osawanomachi, Kami-Nikawa-gun, Toyama Prefecture (Lat. 36°40'09"N., Long. 137°12'58"E.). Kashio alternation of Kurosedani formation. Early Miocene. Distribution: — Kurosedani formation, Toyama Prefecture; Kobana formation, Tochigi Prefecture: both Early Miocene in age. Occurrence: — Few in the granule conglomerate of the Kurosedani formation. MASUDA, K. 1962. Tertiary Pectinidae of Japan. The Science Reports of the Tōhoku University [2nd. Series -Geology], 33 (2): 117-238, pls. 18-27. [p. 193]
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Placopecten osawanoensis (Tsuda); K. Masuda, 1962, Tertiary Pectinidae of Japan, plate 24, figure 10; plate 25, figure 8.
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