"Geographic Variation in Red-backed Mice (Genus Clethrionomys) of the Southern Rocky Mountain Region" by E. Lendell Cockrum and Kenneth L. Fitch is a scientific publication written in the early 1950s. The book serves as a detailed examination of the red-backed mice, specifically focusing on their geographic variation across the southern Rocky Mountain region. Through this work, the authors aim to clarify the taxonomic status of these small mammals and recognize unnamed subspecies in the area. The book presents extensive findings based on the authors’ research into the red-backed mice, comparing physical characteristics such as pelage and cranial measurements across various geographic variants. The study identifies several distinct subspecies within the genus Clethrionomys, utilizing collected specimens from multiple locations in Wyoming, Colorado, New Mexico, and Arizona. Through detailed descriptions and taxonomic analysis, the authors provide insights into the morphological traits that differentiate these subspecies, contributing valuable knowledge to the field of mammalian biology and aiding in understanding the ecological adaptations of these mice within their diverse habitats. (This is an automatically generated summary.)