Two species of well-preserved phyllocarid crustaceans, Ceratiocaris macroura n. sp. and Ceratiocaris papilio Salter, occur in the Eramosa Formation Lagerstätte of Ontario, Canada, represented by several dozen articulated fossils preserving limbs and thoracic segmentation. Ceratiocaris macroura n. sp. is distinguished by possession of an exceptionally elongate telson in relation to its body length. Ceratiocaris papilio preserves fine detail of the abdominal scale-like ornamentation, allowing reinterpretation and enhanced characterization of this key feature. Ceratiocaris papilio has a wide paleogeographic distribution across Laurentia but is restricted to shallow marine depositional settings within the middle Silurian.