'Calcispheres' and forms belonging to 'calcisphere de forme A' of Lombard and Monteyne (1952) were found in subsurface samples of the Duperow Formation of Late Devonian age in western North Dakota. 'Calcisphere de forme A' belongs to the foraminiferal genus Umbellina (Maslov). The microfossils occur most abundantly in calcarenitic limestone but are also present in calcarenite and fine-grained limestone.

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