Eleven species of trilobites from the Pleasant Hill Limestone in Blair and Huntingdon Counties are described and illustrated. A new genus, Blairella (type species: B. crassimarginata n. sp.) is proposed. Other new species are Alokistocare nasutum, Blainia buttsi, Blairella triangularis, Elrathia grazierensis, Olenoides pennsylvanicus, O. buttsi, Solenopleurella elatifrons and S. transversa. There seem to be no appreciable age differences among the various collections. The faunule is of late medial Cambrian age, as it includes genera known from the Bolaspidella zone of the West. Some of the species also occur in the Maryville Limestone of northeastern Tennessee.