Abstract The Paleozoic rocks of the Ouachita Mountains (westcentral Arkansas and southeastern Oklahoma) consist primarily of sparsely fossiliferous deep-water deposits. Until recently, graptolites have provided most of the biostratigraphic evidence for the correlation of these rocks with sections in other parts of North America. Conodonts have been known from the Arkansas Novaculite for over 60 years, but their presence in limestones within the dominantly shaly Ordovician part of the sequence was demonstrated only recently (Repetski and Ethington, 1977). Shelly fossils are almost unknown from the pre-orogenic rocks of the Ouachita Mountains, although fragments of brachiopods, bryozoans, and trilobites have been found in acid residues of limestones thatwere processed for conodonts.