Failure of Survival of Slowly Growing Members of a Population

In December 1958 the Lamont Geological Observatory research vessel "Vema" dredged four specimens of Monoplacophora from the Peru-Chile Trench off northern Peru. This is the second discovery of living representatives of this class of Mollusca which was thought, until 1957, to have become extinct in the Devonian. The specimens are considered to represent a new subgenus and species: Neopilina (Vema) ewingi , and the discovery suggests that more relict types may exist alive in the deep sea off Central and South America.