No foraminifera or other fossils were found in the lowest part of the Mount Toondina Beds, as identified on lithological and geophysical criteria. Immediately below the contact (990 feet) with Unit 1 (i.e. partly equivalent to and presumably continuous with the Stuart Range Beds) there are abundant arenaceous foraminifera, very low diversity and dominated by Ammodiscids. In this aspect the assemblage is new and its interpretation therefore remains uncertain. There is a decrease in specimen numbers below the uppermost 20 feet but the assemblage was found in all cuttings samples examined down to 1340 feet i.e. throughout Unit 1. No fossils were found below Unit 1. These results are consistent in part with previous studies in the Arckaringa Sub-basin, but peculiarities in faunal composition and distribution show that this "marine interval" is more variable in biofacies than was known previously.