_Remarks._--The specimen from "Petén" (USNM, no. 4941) is the only specimen that has a controversial history. As can be seen from the synonymy of the species, the relationship of this specimen with the rest of the genus has been interpreted in several ways. Smith (1941:122-123) stated that the above specimen was catalogued as being from El Salvador; however, the locality was presumed by him to be El Petén, Guatemala, due to the presence in the bottle of a piece of paper inscribed "_Conophis vittatus_, Petén, J. M. Dow." This specimen is the one mentioned by Cope (1861:300, 1876:76, and 1900:1094-95), and in the first paper is ascribed to Guatemala. In 1900 this specimen was named _C. lineaticeps_ by Cope who thought the specimen differed significantly from _C. concolor_ (Cope, 1867:318-319). This specimen has the coloration normal for _C. l. concolor_ as far posteriorly as mid-body; beyond mid-body the dark lines, typical of _C. l. lineatus_ or of _C. l. dunni_, are present. It is likely that this specimen is an intergrade between _C. l. concolor_ and _C. l. dunni_, the other subspecies present in Guatemala. The only specimen not from the Yucatán Peninsula is allegedly from Patuca, Honduras (USNM 20271). It was obtained in the 1870's. Possibly more collecting will verify the presence of _C. l. concolor_ in northern Honduras. This individual may be merely a genetically aberrant specimen from an area where normal specimens are _C. l. dunni_. Neill and Allen (1961:44-45) suggested that the specimen from Patuca implies widely overlapping distributions for _C. l. dunni_ and _C. concolor_. The occurrence of _C. l. concolor_ in Honduras needs to be verified before this assumption is made. There can, therefore, at present be no objection to the view that intergradation between the subspecies _C. l. dunni_ and _C. l. concolor_ could occur through a relatively broad area of El Petén and British Honduras. Neill and Allen (1961:44-45) further suggest that the present range of _C. l. dunni_ extends "presumably still farther northward toward the Méxican state of Veracruz where _C. l. lineatus_ exists." Actually the presence of the subspecies _C. l. dunni_ and _C. l. lineatus_ as presently disjunct populations implies merely that they were presumably a continuous population at some time in the past. The characteristics of the genus in combination with the reduction of dark coloration posterior to the head distinguish this snake from all other snakes in México and Central America. _Distribution._--The Yucatán Peninsula: eastern Campeche, all of Yucatán, probably in Quintana Roo, and the northern third of British Honduras. A record for northeastern Honduras is questioned (fig. 2). _Specimens examined._--Total of 48, as follows: BRITISH HONDURAS: _Belize District_: 13.0 mi. W, 1.5 mi. S Belize, ERA-WTN BH-1562. GUATEMALA: _El Petén, no specific locality_, USNM 4941. HONDURAS: _Colón_: Patuca, USNM 20271.