Conodonts from the St. Louis formation (Valmeyeran series) of Illinois, Indiana, and Missouri

The conodont faunas of the St. Louis Formation were studied from the longest and best exposures in the Mississippian outcrop belt around the Illinois Basin, including type sections of both the St. Louis and Ste.Genevieve Formations.Faunas were found to be common in the upper part of the St. Louis but sparse in the lower.Altogether they consist of 2 1 species, representing the genera Apatognathus ?, Cavusgnathus , Hibbardella , Ligonodina , Lonchodina, Magnilaterella , n.gen., Neoprioniodus , Ozarkodina , Spathognathodus , Taphrognathus and one un- named new genus.Three new taxa, Magnilaterella , n.gen., Magnilaterella robusta , n.sp., and Ozarkodina laevipostica , n.sp., are proposed herein.Two genera from the St. Louis are especially useful for biostratigraphic zonation: Taphrognathus was found to occur only as high as the middle of the formation and Cavusgnathus no lower than the middle.In addition, three species, Apatognathus ?gemma, A? porcata , and Spathognathodus scitulus , are common and.confined to the upper part of the formation.In general, the conodont faunas of the St. Louis are transitional with those of the underlying Warsaw and Salem Forma- tions and are abruptly different from faunas of the overlying Ste.Genevieve Formation.Within the St. Louis there are distinctive but transitional faunal differences between upper and lower parts of the formation.