Pump samples filtered from the sea-water tap have been used to determine microplankton volumes, species diversity and faunal composition in the different water masses sampled by the Amsterdam Mid North Atlantic Plankton Expedition between 55°N 30°W and 24°N 30°W in the period 9 April – 6 May 1980. The presence of a plankton bloom south of 40°N could be demonstrated. Six faunal assemblages are distinguished, viz.: Subarctic, Cold Temperate, Warm Temperate, N. Sargasso Sea, S. Sargasso Sea and a more Tropical assemblage. Some traces of upwelling near 55°, 48° 38° and 30°N could be demonstrated by the presence of benthic Foraminifera in these shallow samples. A list of samples is provided.