Cooper, J. G. 1859. Report on the Reptiles Collected on the Survey. Cooper, J. G., and G. Suckley eds., The Natural History of Washington Territory with Much Relating to Minnesota, Nebraska, Kansas, Oregon, and California Between the Thirty-sixth an Forty-ninth Parallels of Latitude Being those Parts of the Final Reports on the Survey of the Northern Pacific Railroad Route, Containing the Climate and Physical Geography, with Full Catalogues and Descriptions on the Plants and Animals Collected from 1853 to 1867: 292–306, Plates XII–XXXI. New York, Ballière Brothers.