This is a report on the snakes of western Chihuahua that were taken at intervals from 1956 to 1972. At no time did we attempt to collect east of Highway 45, rather expending our time in the foothills, valleys, and desert ranges east of the mountains and in the highlands of the Sierra Madre Occidental. Reference is made to reports on the geological and ecological aspects of the area as a whole, but without a major attempt to duplicate previous studies. A brief gazetteer and a map are included as guides. To provide orientation to the area traversed by the John Cross expeditions, a map of the lower Rio Urique and Rio San Miguel is also included. From the area studied, 28 genera and 51 species are listed, with three new subspecies described: two worm snakes (Leptotyphlops humilis chihuahuaensis and Leptotyphlops dulcis supraocularus) and a garter snake (Thamnophis rufipunctatus unilabialis). For a number of species it became necessary to expand the study into populations from adjoining states in Mexico and the United States. Such species as T. rufipunctatus and R. Hesperia are examples. Where data were available systematic relationships were implied, as well as ecological and biological data.
Tanner, Wilmer W.
"Snakes of western Chihuahua,"
Great Basin Naturalist: Vol. 45
, Article 4.
Available at: http://scholarsarchive.byu.edu/gbn/vol45/iss4/4