A road cut in Butler County exposes layers of fossiliferous limestone and shale from the Winfield Limestone. The outcrop contains numerous fossils, including bryozoans, echinoids, crinoids, and at least three genera of brachiopods. The majority of the fossils found at this outcrop are Derbyia brachiopods. The interareas of the Derbyia shells range significantly in height and width. To test whether the variation in the interareas represents intraspecific variation or diversity of a single species, several Derbyia shells where collected, cleaned, and measured. A plot of height versus width of the interareas reveals that the Derbyia shells fall into two groups. Most of the shells are wider than tall. These shells have been identified as Derbyia filosa. Five shells are taller than wide and have been identified as Derbyia profunda. The presence of two similar species from the same location suggests niche partitioning. It is suggested that the living brachiopods lay on the sea floor and the height of the shells relates to the looseness of the underlying sediment.