Pecten (Chlamys) jordani Arnold, 1903
ARNOLD, R. 1903. The Paleontology and Stratigraphy of the Marine Pliocene and Pleistocene of San Pedro, California. Memoirs of the California Academy of Sciences, 3: 1-420, pls. 1-37. [p. 111, pl. 12, figs. 6-7]
«30. Pecten (Chlamys) jordani, sp. nov.
PLATE XII, FIGS. 6 AND 7. Shell of medium size, shape of P. hericeus, inequivalve, rather thin; right valve with twenty five to thirty angular, smooth-topped, imbricated ribs, which become dichotomous after reaching a length of about 30 mm.; interspaces deeply channeled and narrower than ribs; anterior ear imperfectly radially ribbed with six ridges, and showing elevated, concentric, incremental lines; posterior ear nearly obsolete, showing four ribs; byssal notch not deep; left valve shows twenty-five to thirty narrow, convex ribs, showing imbrications only slightly; interspaces as large as ribs; after a diameter of about 30 mm. has been reached by the shell, small riblets appear in the widening interspaces; anterior ear shows five narrow, imbricated ridges, with wide interspaces; both valves show a tendency to contract suddenly at the basal margin upon nearing completion of growth; surface of both valves covered with a minute, lattice-like sculpture, which is generally worn off on exposed portions of the shell.
Dimensions.— Long. 42 mm.; alt. 45 mm.; diam. 15 mm.; hinge 18 mm. Allied to P. opuntia Dall, but having fewer ribs on disk and ear, and having dichotomous ribs after reaching a diameter of 35 mm. Distinguished from P. hericeus and P. hastatus by not having fasciculated nor spinose ribs. Rare in Pliocene of Deadman Island and lower San Pedro series of Deadman Island. Found also in Pliocene of Packard's Hill and Pleistocene of bath-house, Santa Barbara. The specimen figured is the type, which is from the Pliocene of Deadman Island and is now in the United States National Museum. Pleistocene.— San Pedro, Santa Barbara (Arnold). Pliocene.— San Pedro, Santa Barbara (Arnold).» RALPH ARNOLD, 1903
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R. Arnold, 1903, plate 12.
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