The insects now described come from three different localities and horizons.One species was obtained by the United States Geological Survey in the oil shales (Eocene) of western Colorado.Others are from Florissant, Colorado, where they were obtained in the wellknown Miocene shales.These include, in addition to a number of new species, new genera of Diptera and Hymenoptera.
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T. D. A. Cockerell (1917) studied this question.
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