Abstract

A bryozoan faunule including 15 species has been collected from the upper 5 ft. of the Osgood formation (Niagaran [Silurian]) as exposed in the Southeastern Materials Corporation quarry in the SW 1/4, sec. 22, T. 8 N., R. 11 E. at Osgood in Ripley County, Indiana. The following new species are established: Ceramopora vesicularis, Fistulipora promiscua, Heterotrypa? perplexa, Cyphotrypa osgoodensis, Stigmatella dubia, Hennigopora apta, and Monotrypa exserta. An unnamed species of Trematopora Hall is described. The bryozoans are associated with brachiopods, trilobites, corals, cystoids, nautiloids, and abundant arenaceous foraminifers. The fossils are embedded in gray highly calcareous shale that contains thin beds of gray coarse-grained argillaceous limestone. The most abundantly represented genus is Fistulipora McCoy; specimens of this genus are assigned to the new species Fistulipora promiscua which displays considerable structural variability in tangential and longitudinal sections. The next most abundant genus is Monotrypa Nicholson which is represented by 3 species. The bryozoan genera in this faunule include: Ceramopora Hall, Cheilotrypa Ulrich, Heterotropa.? Nicholson, Cyphotrypa Ulrich & Bassler, Stigmatella Ulrich & Bassler, Hennigopora Bassler, Hallopora Bassler, Trematopora Hall, Diplotrypa Nicholson, and Pachydictya Ulrich. Stigmatella, Heterotrypa?, and Cyphotrypa have not been reported previously from the Osgood. Specimens of fenestellid bryozoans are rare and poorly preserved.

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