Certain nearshore facies of the upper half of the Pennsylvanian System in the Mid-Continent region are characterized by faunas which are dominantly molluscan. Although individual faunules are reasonably well known, few comparisons have been made between successive faunas. Five molluscan faunules ranging in age from Desmoinesian to Virgilian were examined on the specific and supra-specific levels. The abundance of individual species, genera, and families within each formation, variations in the abundances with time, and the phylogenetic changes aid in the interpretation of the paleoecologies of these unusual populations.

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