Sixteen species of Mexican snakes are discussed. Range extensions are noted for Lampropeltis triangulum annulata, Lampropeltis getulus nigritus, Pituophis catenifer affinis, Toluca lineata lineata, Salvadora intermedia, Trimorpho- don latifascia, Trimorphodon lambda, and Crotalus trigris. An altitudinal record of 5,200 feet is reported for Crotalus basiliscus basiliscus. Additional data are pre- sented on three rare snakes, Lampropeltis getulus nigritus, Trimorphodon tau, and Leptodiera punctata. Crotalus intermedius gloydi is considered a valid subspecies occupying the Oaxacan highlands. The name Salvadora intermedia richardi Smith appears to be based on an individual variant and should be submerged. The authors question the inclusion of Lampropeltis polyzona Cope in the species complex Lamproeltis triangulum and they suggest that Salvadora bairdi and S. lineata are not specifically distinct but rather are geographic races of S. bairdi. In the course of gathering biological and distributional data on Mexican toads of the Genus Tomodactylus during June and July, 1956, the junior author and his wife, Mary, collected several specimens of Mexican snakes. Some of them are of particular interest in that they constitute new distributional records or are of taxonomic importance. All specimens here discussed are deposited in the Texas Cooperative Wildlife collection, Texas A. and M. College.