Chlamys egregius Itoigawa, 1955
ITOIGAWA, J. 1955. Molluscan Fauna of the Mizunami Group in the Iwamura Basin. Memoirs of the College of Sience, University of Kyoto [Serie B], 22 (2): 127-143, pIs. 5-6 [p. 138, pl. 5, figs. 7-9]
«Chlamys egregius n. sp. (PI. V, figs. 7-9)
Shell moderate in size, suborbicular, higher than long, nearly equilateral, compressed, with indistinct concentric growth lines and radial sculpture; beak small sharply pointed; apical angle about 90°; anterior side slightly convex, posterior gently concave in the middle; ventral margin rounded; right valve with about 16-12 primary ribs ana a few splitted subsidiary ones; ribs broad, rounded, unequal, not high with a few longitudinal striae on the back, separated by shallow smooth·bottomed valleys of narrower breadth; rib on the left valve also usually 16-12 in number, narrower than interspaces, flat· topped, unequal; interspace with fine reticulated sculpture; anterior ear of left valve with 5 weak scaly ratlial riblets, that of the right valve subdivided into 4 irregular radial riblets on the upper arel; the lower byssal area furnished with flexuous, lamellated, horizontal, incremental lines; byssal notch distinct, hyssal comb well maked; incremental lines very fine, not imbricated; interior obscurely radially grooved, ventral margin crenulated.
Dimensions: Height, 29 mm.; length, 26 mm.; thickness of the right valve 4 mm. Holotype: JC 1300018, Paratype: JC 1300019, JC 1300020 (from 112-2, Kamigiri) Occurrence: Kamigiri (111, 112-2, 113), Nakanishi (245)... Kubohara sandstone; Hachiyato (1-1, 185), Maki (267)... Maki siltstone No allied species is known among the Recent and fossil species. Apparently this species is similar to Patinopecten kimurai (YOKOYAMA) (1925), a well known Miocene scallop, but the new species having well marked byssal comb obviously belongs to the Genus Chlamys. The ribs are variable in number 12 to 16. The individuals with few ribs have left valves with fine and ridged ribs. Therefore, it may be subdivided into some subspecific groups in future when a sufficient material is supplied.» JUNJI ITOIGAWA, 1955
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J. Itoigawa, 1955, plate 5.
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