_Remarks._--I have been unable to find variation of geographic importance in scutellation in this species. A wide range of variation in the characters of scutellation is present in specimens from most localities; it shows no significant clinal or geographic trends. As I have stated previously, in the discussion of variation, coloration has been the feature primarily used by previous workers to distinguish two "subspecies" for this species; _C. vittatus vittatus_ having four black stripes and _C. vittatus viduus_ having three black stripes. Most of the three-striped snakes occur in the vicinity of Tehuantepec, Oaxaca, whereas the four-striped snakes are found near the margins of the range of the species in Durango, Colima, Michoacán, Morelos and Puebla. Specimens that would have to be considered intergrades between the "subspecies" are found in Michoacán, Guerrero, Oaxaca and Chiapas. At the time the subspecies were proposed only specimens from Tehuantepec or from marginal areas were known. Utilizing the large number of specimens of this species presently available, geographic variation is found to be clinal, from those with three stripes from near Tehuantepec, through several intermediate patterns present on specimens from single localities in Guerrero, Oaxaca and Chiapas, to those with four dark stripes in areas farthest removed to the north and west from Tehuantepec. Since only coloration shows geographic variation, and since this variation represents a continuous cline, subspecies cannot be recognized for this species. The presence and position of the three or four dark stripes on the body and the absence of brown on the 1st scale-row or on the ventral scales, in combination with the generic characters, distinguish _Conophis vittatus_ from all other Méxican snakes. The only other snake that occurs in western México that has been confused with _C. vittatus_ is _Coniophanes piceivittus taylori_, which has 25, instead of 19, scale-rows. _Distribution._--Semi-arid habitats on Pacific slopes from extreme southern Durango southeastward to Tuxtla Gutierrez, Chiapas, and inland in the eastern Balsas Basin to Morelos and western Puebla (fig. 5). [Illustration: FIG. 5. Selected locality records for _Conophis vittatus_.]