Cranial remains of Eumys elegans from Chalky Buttes, southwestern North Dakota, were examined and a composite diagram of a skull created. Eumys elegans is fully myomorphous and has a derived carotid artery circulation that is also found in some Old and New World muroids. Expansion of the posterior end of the jugal bone to form an articular surface that is part of the glenoid fossa is unusual in muroid rodents. The lower dentition is highly variable in both transverse crests and the connections of cusps to crests. Continuous variation in dimensions and heterogeneous molar crown morphology within individual tooth rows of a large sample of lower dentitions from Chalky Buttes suggest that only one, highly variable species was present. Variation in the upper dentition appears to be less. The rare enclosure of internal basins in the upper teeth parallels that development in other groups of muroids.