Chlamys opuntia (Dall, 1898)
Description: Shell is taller than wide (though only slightly so), with anterior auricles larger than those of the posterior, and a moderately deep byssal notch. Sculpture of 40-60 narrow, scaled ribs, which are separated by channeled interspaces of equal width to ribs.
Size: 35-40 mm.
Ecology: Epifaunal and attached on coarse sediment or hard substrates on the continental shelf (0-200 m of water depth).
Geological range: Extinct; Late Miocene-Pleistocene (7-0.1 million years ago).
Geographic distribution: Central California (38°N) to Baja California Sur, México (30°N). Reported from the Purisima Formation (Late Miocene-Pliocene, California), Niguel Formation (Pliocene, California), Merced Formation (Pliocene-Pleistocene, California), Pico Formation (Pliocene-Pleistocene, California), San Diego Formation (Pliocene, California), unnamed Pliocene strata on San Clemente Island, Lomita Marl (Pleistocene, California), and San Pedro Formation (Pleistocene, California).
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