Laevichlamys shirahamaensis (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. 175, pl. 12, figs. 5, 5a]
1962 Pecten (Pecten) shirahamaensis Nomura & Niino, 1932
S. Nomura & H. Niino, 1932, plate 12.
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«A single individual, both valves jointed.
Shell attains about 40 mm. in height, suborbicular, slightly convex, higher than long, subequivalve, equilateral except for ears; test medium in thickness; sides slightly concave in the middle; base regularly rounded. Right valve with numerous, unequal, rounded, narrow and more or less imbricated ribs which multiply, both by division and intercalation, up to about 45 in number near the ventral border of the disk; interspaces narrow, subchanneled; hinge-line much longer than one-half of disk-length. Ears very unequal; anterior ear being larger than the posterior, produced, sculptured by prominent concentric, imbricating lines as well as few (5?) radiating riblets; byssal notch quite prominent, rather deep and triangular; posterior ear nearly half the length of the anterior, sharply truncated obliquely, sculptured as in the anterior, though with the radial riblets less prominent. Left valve similar to the right except of possibly being a little more convex. Dimensions:— Height, 42 mm.; length, 38 mm.; hinge line, 26.5 mm. ; depth, ca. 12 mm. (both valves). This species somewhat resembles P. islandicus MÜLLER of the Arctic seas, but is distinguished mainly by the ears. P. halimensis MAKIYAMA from the Pliocene of Harima² also resembles the present species although specifically may be distinct. Occurrence: Nagata in Shirahama-mura (Shirahama Group).» ² MAKIYAMA J.: Some Pliocene Mollusca from Maiko, near Kobe. Jap. Jour. Geol. Geogr., Vo!. 11, No. 2, 1923, p. 23, pI IV, fig. 1. SHICHIHEI NOMURA & HIROSHI NIINO, 1932
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«There is still much to learn about the fossil record of this genus [Laevichlamys], but two extinct species are included thus far: Pecten (Chlamys) lauensis Ladd in Ladd and Hoffmeister, 1945, Fiji, late Miocene or Pliocene; P. shirahamaensis Nomura and Niino, 1932, Japan, Early Pliocene (Masuda, 1962, p. 185).»
WALLER,
T. R. 1993. The evolution of Chlamys (Mollusca: Bivalvia: Pectinidae)
in the tropical western Atlantic and eastern Pacific. American
Malacological Bulletin, 10 (2): 195-249, figs. 1-14. [p. 204]
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Chlamys shirahamaensis (Nomura and Niino); K. Masuda, 1986, Notes on the origin and migration of Cenozoic pectinids in the Northern Pacific, plate 10, figure 4.
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