In his "Revision of the pocket mice of the genus Perognathus," Osgood (1900:18-20) reviewed the distribution, as then known, of Perognathus fasciatus and recognized two geographic races— Perognathus fasciatus [ fasciatus ] Wied-Neuwied in eastern Montana and Wyoming and adjacent parts of North and South Dakota, and Perognathus fasciatus infraluteus Thomas, known only from the type locality at Loveland, Larimer County, Colorado. Later, Cary (1911:61) described Perognathus fasciatus litus as a pal