All specimens from Michoacán are from inland localities between 300 and 1500 meters. The one from Los Reyes (USNM 46416) was collected by Nelson and Goldman on February 13, 1903. The elevation of Los Reyes (1500 meters) seems unusually high for this species, but otherwise there is no reason to doubt the authenticity of the record. Goldman (1951:192) in his description of Los Reyes stated: "Los Reyes is near the boundary between the Lower Austral and Arid Upper Tropical Zones but is preponderantly tropical in zonal character. The regular crops are mainly sugar cane, rice, and corn." Thus the biotic features of the area are not noticeably different from those at El Sabino and La Playa at lower elevations. The development of extensive agriculture through irrigation in the Tepalcatepec Valley and planting of rice and sugar-cane in that area may produce a more widespread habitat for this snake. The absence of specimens from the coastal lowlands is due solely to inadequate collecting; the natives there know the snake and report that it is not uncommon in certain areas. ~Crotalus basiliscus basiliscus~ (Cope) _Caudisonia basilisca_ Cope, Proc. Acad. Nat. Sci. Philadelphia, September 30, 1864.--Colima. Type locality restricted to Colima, Colima, México, by Smith and Taylor (1950a:328). _Crotalus basiliscus basiliscus_, Gloyd, Nat. Hist. Misc., 17:1, April 23, 1948. Apatzingán (4); Camachines; Coalcomán; El Ticuiz. Specimens from southern Michoacán have fewer ventrals and caudals than do those from the northern part of the range; three males and three females have, respectively, 178, 182, 182, 185, 186, and 188 ventrals, and 27, 28, 29, 22, 29, and 29 caudals. Klauber (1952:81) gave the following data for _Crotalus basiliscus_ (based on specimens from the entire range, except Oaxaca): ventrals in males, 179-201 (191.4), in females, 185-206 (197.6); caudals in males, 26-36 (30.7), in females, 21-29 (24.4). Klauber (1952:84) remarked that the one specimen that he had seen from Apatzingán had fewer ventrals and caudals than most other specimens. The low numbers of ventrals and caudals in specimens from Michoacán, as compared with more northern populations, may be indicative of a trend in the reduction of the numbers of these scutes from north to south. The southernmost examples of _Crotalus basiliscus_ (_Crotalus basiliscus oaxacus_ from Oaxaca) have 172-175 ventrals and 21 caudals (Gloyd, 1948). In Michoacán _Crotalus basiliscus basiliscus_ has been found in arid habitats on the coast, in the Tepalcatepec Valley, and in the lower parts of the Sierra de Coalcomán. All specimens are from localities below 1070 meters in elevation. ~Crotalus durissus culminatus~ Klauber _Crotalus durissus culminatus_ Klauber, Bull. Zool. Soc. San Diego, 26:65, August 8, 1952.--El Sabino, Michoacán, México. El Sabino (18).