The one specimen from Michoacán was collected by Peters (1954:30) in tropical semi-deciduous forest on the coastal foothills of the Sierra de Coalcomán. As presently known, the range of this species in western México extends from Chiapas to Nayarit. Throughout this region the species avoids scrub forest; this may explain its absence in the Balsas-Tepalcatepec Valley. ~Sonora michoacanensis michoacanensis~ (Dugès) _Contia michoacanensis_ Dugès, _in_ Cope, Proc. Amer. Philos. Soc., 22:178, 1885.--Michoacán. Type locality restricted to Apatzingán, Michoacán, México, by Smith and Taylor (1950a:335). _Sonora michoacanensis michoacanensis_, Stickel, Proc. Biol. Soc. Washington, 56:116, October 19, 1943. Apatzingán (3); Coalcomán (3); 12 km. S of Tzitzio. These specimens, together with all known specimens from the Sierra del Sur in Guerrero (KU 23790-1, MVZ 45123) and the upper Balsas Basin in Puebla (UIMNH 41688), are referable to _S. m. michoacanensis_. The dorsal pattern consists of a highly variable number of cross-bands of red, white, and black. In the specimens from Michoacán there are as many as 17 red cross-bands on the body. One specimen from Apatzingán (CNHM 37141) has just behind the head a white band, bordered on either side by a narrow black band; posteriorly the body is uniform red. Two specimens from Coalcomán (UMMZ 109905-6) have respectively 11 and 13 red cross-bands and 20 and 17 white cross-bands, and the posterior part of the body is devoid of red color. Other specimens from these localities have red, black, and white cross-bands throughout the length of the body. _Sonora michoacanensis michoacanensis_ is distinguished from _S. michoacanensis mutabilis_ by the presence of cross-bands on the tail in the latter (Stickel, 1943:116). One specimen from Coalcomán (UMMZ 109904) has one narrow band on the tail; all others from Michoacán have uniformly red tails. Apparently _Sonora michoacanensis michoacanensis_ ranges in semi-arid and arid habitats from the upper Balsas Basin in Puebla westward to the lower slopes of the Sierra de Coalcomán, whereas _S. m. mutabilis_ lives in foothills of the Sierra Madre Occidental from southern Jalisco to Nayarit. Zweifel (1959b:6) presented evidence to show that specimens of _S. m. mutabilis_ supposedly from "Distrito Federal" probably bear erroneous locality data. ~Tantilla bocourti~ (Günther) _Homalocranium bocourti_ Günther, Biologia Centrali-Americana, Reptilia, p. 149, 1895.--Guanajuato, Guanajuato, México. _Tantilla bocourti_, Cope, Amer. Nat., 30:1021, December, 1896. Carapan; Pátzcuaro (2); between Zitácuaro and Río Tuxpan (11). This small snake is an inhabitant of the coniferous forests and the pine-oak forests on the Cordillera Volcánica. Data on the series from between Zitácuaro and the Río Tuxpan were given by Taylor (1940c:481). ~Tantilla calamarina~ Cope