Nanaochlamys notoensis setanensis Kanno, 1962
KANNO, S. 1962. Molluscan fauna from the so-called Setana Formation, southwestern Hokkaido, Japan. Science Reports of the Tokyo Kyoiku Daigaku [Section C -Geology, Mineralogy and Geography], 8 (73): 49-62, pls. 1-5. [p. 56, pl. 3, figs. 1, 2]
«Nanaochlamys notoensis setanensis KANNO, n. subsp.
PI. Ill, Figs. 1-4
Nanaochlamys notoensis, MASUDA, 1960, Sci. Rep. Tohoku Univ., ser. 2, Spec. Vol., no. 4, pp. 373-375, pI. 39, fig. 1.
Shell large, about 100 mm in length, but less than 89 mm (usually 75 mm) in the species. In the right valve, the ribs increase chiefly by bifurcation and intercalation of auxiliaries; bifurcation of both tertiary and secondary ones; intercalation of ribs between primary and secondary distinct. In left valve the multiplication of ribs is caused chiefly by intercalation and by bifurcation; the primary intercalaries appears at about 15 mm from the beak, the secondary at about 23-30 mm, and the tertiary at about 34-70 mm from the beak. However, the tertiary intercalaries do not always appear on the immature specimens. These intercalaries increase their number as shown in Table 2; first bifurcation begins at end of platform-like disc, about 26 mm from the beak; the secondary ones appear ventrally in central part of radials.
Comparison: The present subspecies is closely akin to the species in the young stage but the former differs from the latter by having larger shell, distinct ctenolium, and more complicated multiplication of radial ribs shown in Table 2. Remarks: The present subspecies is characterized by having more complicated radial ribs, so that its immature specimens show the same ornamentation as the species (PI. 3, fig. 3). Accordingly, the subspecies is a descendant of the species.
Reg. No. 6583 (holotype), no. 6584 (paratype). Localities and geological horizon: Cliffs of the Meppu River near the Kaigara Bridge, Meppu, Imagane-machi. Meppu sandstone member of the Yakumo formation (Miocene).» SABURO KANNO, 1962
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S. Kanno, 1962, plate 3.
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