Stickel, W. H. 1943. The Mexican snakes of the genera Sonora and Chionactis with notes on the status of other colubrid genera. 56 122.
Kennicott, R., Baird, S. F., et al. 1859. in Report on the United States and Mexican boundary survey, made under the direction of the secretary of the Interior. 35 pp., [131] plates.
Type Status:
Lectotype
Syntype
Place:
Eagle Pass, Maverick, Texas, United States, North America