Coralichlamys shigemai Hirayama, 1954
HIRAYAMA, K. 1954. Miocene Mollusca from the Arakawa Group, Tochigi Prefecture, Japan. (Part 1). Science Reports of the TokyoKyoiku Daigaku [Section C -Geology, Mineralogy and Geography], 3 (18): 43-75, pls. 3-5. [p. 51, pl. 3, fig. 2]
«Coralichlamys shigemai HlRAYAMA, n. sp.
PI. III, Fig. 2. Shell small in size, apparently thin, subcircular in shape, ears unequal, surface provided with radial riblets. Shell with antero- and postero -dorsal sides rather steeply sloping into acutely rounded ventral margin; moderately inflated, maximum inflation near umbonal region, apical angle 96°. Surface with about 38 radial ribs at ventral margin, which are irregularly spaced, being about equal to or slightly broader than their interspaces on the anterior part and about equal to or slightly narrower than their interspaces on posterior part; radials increasing ventrally through bifurcation which takes place near or on maximum inflation near umbonal region. Prodissoconch apparently smooth or possibly slightly worn. Ears unequal, the anterior being
much larger than the posterior and provided with several rough striae. Byssal notch rather deep. Interior unknown. Dimensions of right valve (in mm), height 15.8, length 15.0, approximate depth 2.5, Holotype. Remarks. — This small, apparently thin-shelled scallop with numerous radials formed by bifuration at an early stage and with very unequal ears seems referable to the genus Coralichlamys as defined by T. Iredale (1939, pp. 346, 355). The type by original designation is Coralichlamys acroporicola IREDALE (Iredale, op. cit., pI. 5, figs. 26, 26a), a Recent shell from Java. Compared with the present species considerable resemblance is noticed, particularly in the small size, type of radial ribs, weak scaly nature of their backs and unequal ears. However, the present one can be distinguished from the type species by being slightly broader and consequently with larger apical angle, and with a greater number of radical ribs. The specific name is given in honor of Mr. Shigema Kawada, my classmate, who kindly gave the writer permission to publish his father's collection. Locality and horizon. — Loc. 2, Michinosawa, Oyamada-shimogô, Oyamada-mura. Lat. 36° 46' 50" N, Long. 140° 13' 10" E. Rare. Kobana formation, Miocene. Reg. No. of Holotype 10109.» KATSUMI HIRAYAMA, 1954
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K. Hirayama, 1954, plate 3.
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