Several species of conodonts in the Columbus and Delaware limestones of north-central Ohio are segregated stratigraphically and form associations that correspond fairly well to lithofacies in which they occur. Polygnathus linguiformis, P. angusticostatus, P. angustipennatus, P. intermedius, and Panderodus sp. appear to have been benthic creatures sensitive to substrate texture and energy levels. Other species of Polygnathus may have been benthic, but a nektonic habit is possible for some. Prioniodina tortoides preferred deep-water conditions but was likely nektonic. Simple-cone taxa other than Panderodus and species of Icriodus are ubiquitous and considered to have been shallow-pelagic plankton...