Distribution patterns exhibited by both living and dead thecamoebinids are discussed in relation to four physiographic subenvironments to the Balize delta, Louisiana. The subenvironments are the channels, submerged levees, interdistributary

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bays, and subaqueous distributary-mouth bars. The living specimens exhibit a primary habitat preference for levee localities, with a subsidiary preference for interdistributary bay locations. This distribution pattern is reflected by the dead forms. Living representatives belong to three families, three genera, and 10 species out of a total of four families, four genera, and 15 species retrieved. Mississippiella multiapertura, n. gen., et n. sp., is described and assigned to the Family Paraquadrulidae. Interactions between measured environmental parameters most frequently involve dissolved oxygen in the four subenvironments. This observation suggests that this parameter is of prime importance in deltaic ecology. However, no single ecologic parameter could be identified as the causativ control to thecamoebinid distribution. The living thecamoebinids appear to be tolerant of significant variation in turbidity, temperature, and alkalinity. The living forms indicate a preference for moderately oxidized to oxidized, low-saline to fresh waters associated with reducing to highly reducing bottom conditions. Taxa occurrences are plotted on probabilistic ternary diagrams in order to differentiate the microfaunas characteristic of the various subenvironment traverses, and on probabilistic target plots for microfaunal differentiation of the subenvironments.

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