Systematic studies based at least in part on specimens from Michoacán have resulted in a redefinition of nine species and subspecies: _Bufo marmoreus_, _Bufo perplexus_, _Anolis nebulosus_, _Anolis nebuloides_, _Sceloporus bulleri_, _Sceloporus heterolepis_, _Sceloporus melanorhinus calligaster_, _Hypsiglena torquata torquata_, and _Hypsiglena torquata ochrorhyncha_. Nine species that previously have been recognized as valid have been placed in synonymy. These are: _Bufo horribilis_ Wiegmann, 1833, and _Bufo angustipes_ Smith and Taylor, 1945, as synonyms of _Bufo marinus_ (Linnaeus), 1758. _Microbatrachylus albolabris_ Taylor, 1940, _Microbatrachylus minimus_ Taylor, 1940, and _Microbatrachylus imitator_ Taylor, 1942, as synonyms of _Microbatrachylus pygmaeus_ (Taylor), 1937. _Phrynohyas corasterias_ Shannon and Humphrey, 1957, as a synonym of _Phrynohyas inflata_ (Taylor), 1944. _Hyla microeximia_ Maslin, 1957, as a synonym of _Hyla eximia_ Baird, 1854. _Hylella azteca_ Taylor, 1943, as a synonym of _Hyla smaragdina_ Taylor, 1940. _Loxocemus sumichrasti_ Bocourt, 1876, as a synonym of _Loxocemus bicolor_ Cope, 1861. _Eleutherodactylus vocalis_ Taylor, 1940, is considered to be a subspecies of _Eleutherodactylus rugulosus_. The populations of _Thamnophis dorsalis_ in the Tepalcatepec Valley are shown to be distinct from those inhabiting the highlands of the state; _Thamnophis dorsalis postremus_ Smith, 1942, is revived for the population in the Tepalcatepec Valley. Descriptions are given of the tadpoles of _Bufo occidentalis_ and _Hyla bistincta_. LITERATURE CITED ANDERSON, J. D. 1960. _Storeria storerioides_ in western Mexico. Herpetologica, 16:63-6, March 31. BOGERT, C. M., and OLIVER, J. A. 1945. A preliminary analysis of the herpetofauna of Sonora. Bull. Amer. Mus. Nat. Hist., 83:297-426, March 30. BOULENGER, G. A. 1885. Catalogue of the lizards in the British Museum, vol. II. London, xiii + 497 pp., November 15. 1894. Catalogue of the snakes in the British Museum, vol. II, London, xi + 382 pp., September 23. CONANT, R. 1953. Three new water snakes of the genus _Natrix_ from Mexico. Nat. Hist. Misc., 126:1-9, September 15. CONTRERAS ARIAS, A. 1942. Mapa de las provincias climatologicas de la República Méxicana. Dir. Meteoro, Hidro. Inst. Geog. México, xxvii + 54 pp. COPE, E. D. 1861. Contributions to the ophidiology of Lower California, Mexico, and Central America. Proc. Acad. Nat. Sci. Philadelphia, 13:292-306, December 28. 1887. Catalogue of batrachians and reptiles of Central America and Mexico. Bull. U. S. Natl. Mus., 32:1-98. DAVIS, W. B. 1954. Three new anoles from Mexico. Herpetologica, 10:1-6, April 20. DAVIS, W. B., and DIXON, J. R. 1957. Notes on Mexican snakes (Ophidia). Southwest. Nat., 2:19-27, January. DAVIS, W. B., and SMITH, H. M. 1953. Lizards and turtles of the Mexican state of Morelos. Herpetologica. 9:100-108, July 22. DIXON, J. R.