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Pholas truncata.
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Pholas crispala (Linnaeus).
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Three specimens of Pholas dactylus in their burrows.
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Pholas costata.
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Pholas melanoura (Sowerby).
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Pholas dactylus (Linnaeus).
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Section through jacket showing borer holes in close proximity. One borer (Pholadidea penita) in place in burrow.
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Pholadidea gabbi Conrad, a boring mollusk from a loose block of sandstone at Fort Mason.
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Dorsal view and side view of Pholadidea penita.
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Shell of Pholadidea penita, a Rock Borer.
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Sample of concrete pile-jacket containing four borers (Pholadidea penita) in a space of 3 inches square. Two of the borers are visible, presence of the others being indicated by openings at lower left.