Slide preparer unknown. Note the label originally said “Navicula firma” but was crossed out to “Navicula maculata.” Possibly from Marblehead, Massachusetts.

Navicula maculata is a species of diatom first identified and described by Arthur Mead Edwards in 1859 in his book “On Diatomaceae collected in the United States. Transactions of the Microscopical Society, New Series 7: 84-91.”