Chlamys ingeniosa (Yokoyama, 1929)
YOKOYAMA, M. 1929. Pliocene Shells from near Nanao, Noto. Imperial Geological Survey of Japan, Report, 104: 1-7, pIs. 1-6 [p. 5, pl. 6, fig. 2]
1929 Pecten (Chlamys) hastatus var. ingeniosa Yokoyama 1929
M. Yokoyama, 1929, plate 6.
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«One right valve only.
Shell moderate in size and thickness, compressed, orbicular, nearly equilateral except for ears, radiately ribbed. Ribs a little over twenty, elevated and rounded, usually dichotomous near the beak with two branches equal or unequal, sometimes single accompanied by a small riblet on each side, minutely scaly; interspaces narrower, sometimes with an interstitial riblet which appears either near the ventral border or higher up, reticulate. Hinge-length almost one-half of shell-length. Ears unequal, anterior longer, both radiately costulate. Byssal notch deep and distinct. Height 65 millim. Length about 63 millim. Depth 13 millim. Hinge length 31 millim. This shell closely resembles Pecten hastatus Sow. var. hindsii Carp. (Arnold, Plioc. a. Quatern. Pectens of California, p.111, pl. 43, figs. 1, 2, 2a) living in Bering Sea as well as on the west coast of America and also fossil in California in which, however, the ribs are said to be smooth. Pecten islandicus Müller (Ibidem, pl. 44, figs. 1, 1a) is also closely allied to ours, thoug the length of its hinge is longer.» MATAJIRO YOKOYAMA, 1929
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«Chlamys oidensis Hatai, Masuda and Noda, 1974, from the middle Miocene Oido Formation in Miyagi Prefecture, Northeast Japan, was formerly considered to be closely related to Ch. (N.) kaneharai (e.g. Hatai et al., 1974). However, its holotype (IGPS 64419; articulated valve) is considered to fall within the intraspecific variation of Chlamys (Leochlamys) arakawai (Nomura, 1935), as shown by Sato (1991). On the other hand, its paratype (IGPS 94427; left valve) is referred to Chlamys (Leochlamys) ingeniosa (Yokoyama, 1929) on the basis of the shell outline and external shell sculpture. The left valves of presumable topotypes of Ch. (L.) ingeniosa were first described and illustrated by Nomura and Tazaki (2007).»
MATSUBARA, T., I. NORO, Y. MATSUURA & T. IRIZUKI. 2014. Miocene Mollusca from the Ichibu Formation on Nishinoshima Island, Oki Islands, Southwest Japan. Paleontological Research, 18 (1): 6-32, figs. 1-11. [p. 19]
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