Spondylus kamitanoensis Kanno, 1958
KANNO, S. 1958. New Tertiary Mollusca from the Chichibu Basin, Saitama Prefecture, Central Japan. Science Reports of the Tokyo Kyoiku Daigaku [Section C - Geology, Mineralogy and Geography], 6 (55), p. 157-229, pls. 1-7. [p. 171, pl. 1, figs. 19a-19c]
1958 Spondylus kamitanoensis Kanno, 1958
S. Kanno, 1958, plate 1.
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«Spondylus n. sp., (aff. nicobaricus SCHREIBERS), WATANABE, ARAI and HAYASHI, 1950, Bull. Chichibu Mus. Nat. Hist., 1, pl. 2, figs. 3.
Shell medium-sized, longitudinally elongate-ovate, with mederately large auricles; left valve sculptured with low and narrow ribs numbering about 9 per 10 mm. on the ventral margin; ribs bearing radial rows of fine scales; of the radial ribs, the primary ones are rather strong and in its interspaces 3-4 fine secondary radial ribs occur. Cardinal area rather narrow, with strong 2 crural teeth. Inner margin of the left valve crenulate. Right valve not known.
Measurement:— Length, 63.5 mm.; height, 51.5 mm.; thickness, ca. 12.0 mm.; length of hinge-line, 25.0 mm. (in holotype). Comparison:—This new species more or less resembles Spondylus nikobaricus SCHREIBERS, now living in southern Japan, but can be distinguished from the present one by having more conspicuous primary radial ribs and spines, and more rounded shell outline. Spondylus cruentus LISCHKE, a common Recent shell in Japan, is another allied species, but the former differs from the latter by having more rounded shell outline, more inconspicuous secondary radial ribs, and more compressed left valve. Remarks:— A few fossil species of Spondylus have been recorded from Japan, they are:
Localities and geological formation:— Loc. 874, a right river-side cliff, about 700 meters northwest of the Bushu-nakagawa Station, Arakawa-mura, Reg. No. 5738 (holotype); loc. 803, a left river side cliff, about 100 meters downstream of a bridge in Tochiya, Chichibu-city, Reg. No. 5739 (paratype). All from the Hiranita formation, Lower Miocene.
Associated fauna:— Calliostoma sp., Turbo (Mormorostoma) tochiyensis KANNO, n. sp. Geographic distribution:— Known only from the present area. Geological range:— Lower Miocene.» SABURO KANNO, 1958
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