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"In the Arcacea the shells are nearly equal, usually thick and furnished with a long row of reeth at the hinge. Among them is the <em>Arca tortuosa</em> the shell somewhat twisted and striated' found in the Indian Ocean." &mdash; Goodrich, 1859

Arca tortuosa

"In the Arcacea the shells are nearly equal, usually thick and furnished with a long row of reeth at…