Decatopecten izuensis (Nomura & Niino, 1932)
NOMURA, S. & H. NIINO. 1932. Fossil Mollusca from Izu and Hakone. Science Reports of the Tohoku University [2nd. Series - Geology], 15 (3): 169-192, pls. 11, 12. [p. 179, pl. 11, figs. 9-13]
1932 Pecten (Decadopecten) izuensis Nomura & Niino, 1932
S. Nomura & H. Niino, 1932,
plate 11. |
«Shell attains about 40 mm. in height, compressed, slightly shorter than high, subequivalve, equilateral; test thick. Left valve with 6 prominent, rounded, subequal ribs accompanying a single riblet on each side of disk; sides straight and smooth; basal margin rounded, umbonal angle 85°; interspaces nearly equal to the ribs, rounded at base; whole surface ornamented by radiating riblets, 7 or 8 in number on a rib, minutely imbricated by the intersection of numerous fine incremental lines; right valve similar to the left except of possibly being a little more convex. Ears mostly fractured in all specimens.
Few ill-preserved specimens. Dimensions:— Height, 34 mm., length, 83 mm. (a left valve) " , 40 mm., " , 33 mm. ( " ) This species is similar to P. plicatus SOWERBY, a living species in Japan, but the main ribs in our species are invariably six in number instead five in SOWERBY's species. Furthermore the ears are quite different in the two. P. radula LINNAEUS from Southern Japan is also related to the present new species, but specifically distinct in having more number of ribs. Occurrence:— Nagata in Shirahama-mura (Shirahama Group).» SHICHIHEI NOMURA & HIROSHI NIINO, 1932
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