A specimen in the British Museum (Natural History), catalogued in 1853 (no. 53.2.4.16), has the locality listed as "México." Since this specimen is of C. l. dunni and this subspecies occurs only south of México, the locality must be considered erroneous; possibly the locality as recorded referred only to the fact that the specimen came from tropical Middle America.
The absence of paravertebral stripes, the presence of a lateral dark stripe on the nape involving the 3rd and 4th rows of scales, and the darkly pigmented 1st scale-row, in combination with the characteristics of the genus, distinguish C. l. dunni from all other snakes in México and Central America. The only sympatric species of this genus, C. pulcher, differs in that it has paravertebral stripes (though never a vertebral dark stripe). Conophis pulcher has a lateral dark stripe that includes the upper half of the second scale-row on the anterior part of the body; stripes of C. l. dunni never include more than the 3rd and 4th rows. Even as juveniles the paravertebral row is not darkly pigmented in C. l. dunni as it is in C. pulcher.
Distribution.—Semi-arid habitats from sea level to elevations of 1000 m. from the Cuilco Valley in western Guatemala, El Peten and British Honduras southeastward to northeastern and southern Honduras, western Nicaragua and northwestern Costa Rica ([fig. 2]).
Specimens examined.—Total of 41 specimens, as follows: British Honduras: Cayo District: Augustine, ERA-WTN BH-300; Mountain Pine Ridge, 10 mi. E Augustine, ERA-WTN BH-298.
Costa Rica: no specific locality, AMNH 17309. "Cartago," BMNH 71.11.22.15. Puntarenas: 32 km. N Barranca, KU 35630; Esparta, USNM 37758. "San José," ANSP 3480, 12232.
El Salvador: Morazan: El Divisadero, CNHM 10999. San Miguel: San Pedro, MCZ 57061.
Guatemala: El Petén: Sojio (Toocog), AMNH 69969, 69986. Huehuetenango: flood plain Río Cuilco, W of Finca Canibal, 18 km. N Tacaná, UMMZ 98283. Santa Rosa: Santa Rosa, UMMZ 107339.
Honduras: no specific locality, AMNH 32814, UF 7657. Cortes: Cofradía, SU 8422; Gracias, CNHM 28560; Hacienda de Santa Ana, W San Pedro Sula, CNHM 5297; San Pedro Sula, UMMZ 68695(2); near San Pedro Sula, MCZ 27563. Francisco Morazan: Potrero de Melio, Escuela Agricola Pan-Americana, MCZ 49987; Tegucigalpa, MCZ 49784, 49786, 49789-90, 49792, 49794.
Mexico: no specific locality, BMNH 53.2.4.16.
Nicaragua: no specific locality, UMMZ 65633, USNM 25237. Leon: El Polvón, MCZ 5645, 5696. Managua: Managua, USNM 79963-64; 3 mi. SW Managua, KU 42315; 8 mi. WNW Managua, KU 42314; 1 mi. N Sabana Grande, KU 42311-13. Matagalpa: 1.5 mi. N Matagalpa, UMMZ 116537.