Entolium yatsujiense Kurata & Kimura in Kimura, 1951
KIMURA, T. 1951. Some pectinids and a limid from the Jurassic Torinosu group in Japan. Journal of the Faculty of Science, University of Tokyo [Section II: Geology, Mineralogy, Geography, Seismology], 7 (6-10): 337-350, pI. 1 [p. 346, pl. 1, fig.18]
1951 Entolium yatsujiense Kurata & Kimura in Kimura, 1951
T. Kimura, 1951, plate 1.
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«Entolium yatsujiense KURATA and KIMURA, n. sp.
PI. 1, Fig. 18. Description:— Shell small, slightly convex, equilateral and almost orbicular; antero-dorsal margin a little convex, and postero-dorsal a little concave; ventral half of the shell semicircular. Ears depressed and very small; hinge line corresponds to about one-third the length of the shell, and their dorsal margins faintly projected upward; there is a faint ridge on the internal mould along the dorsal margin.
Surface quite smooth. Internally ridges bounding the resilifer extend downward in separating the ears from the main part of the shell. Besides them there are two long narrow ridges, like the internal ribs of Propeamussium, which extend from the beak to the antero- and postero-ventral sides, and at the same time become stronger; on the other side they meet with antero- and postero-dorsal margins of the shell forming an angle of about 20 degrees. Dimension:— The Holotype (No. 7105) is 11.6 mm in height and 11.5 mm in length, and its umbonal angle 104 degrees. Comparison:— Though somewhat similar to Entolium japonicum, this species can readily be distinguished from that species by its orbicular outline, smaller ears and characteristic internal ridges. In the Sakuradani district at Choan and Miyakodani there are Entolium which have distinct internal ridges and besides them there are some specimens with faint ones. Because all of these specimens are inseparable with regard to the other characters, they may belong to this species, although some of them have only faint internal ridges. Occurrence:— Yatsuji, Habunokawa, west of Taroda, Go, Nagayasu, Miyakodani and Mimikire.» NOBUO KURATA & TOSHIO KIMURA, 1951
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