Lizards of the genus Cnemidophorus long have been a thorn in the sides of herpetologists. Commonly known as whiptail lizards or racerunners, species in this genus occur in North, Central, and South America. Probably the most confusing thing about these lizards is the ontogenetic change in color pattern, which through its variety of manifestations runs the gamut in convergence and parallelism. The purpose of this study is to review the species of the deppei group of Cnemidophorus and to present a classification of them, using some taxonomic characters that previously have not been applied. During the course of this study, 2,302 specimens were examined, revealing the presence of three species and ten races. The species differ from one another in the relative size of the dorsal granules, the size of the body, color pattern, and ontogenetic change in color pattern. The ranges of the species appear to be discontinuous. The present distributions probably are the result of climatic shifts during the Pleistocene.

William E. Duellman was curator emeritus of herpetology at the Biodiversity Institute and professor emeritus in the Department of Ecology and Evolutionary Biology at the University of Kansas.

John Wellman was a herpetologist at the Museum of Natural History at the University of Kansas.