CHECKLIST OF THE SNAKES OF MEXICO 199 



Range. — "From southeastern Arizona and the Valley of the Rio 

 Grande northwestward to western New York and southern Ontario ; 

 . . . the lower Mississippi Valley and Gulf Coast, all of Florida 

 and the Atlantic Coastal Plain northward into North Carolina, and 

 a small area at the southern tip of the Mexican Plateau in the states 

 of Puebla, Mexico, Hidalgo, Oaxaca, and Veracruz." 



Species. — Six species and subspecies ; only two occur in Mexico, one 

 restricted. 



KEY TO MEXICAN FORMS OF SISTRURUS » 



1. Head with distinct markings or nearly all black ; cantlius rostralis dis- 

 tinct ; rostral high, truncate at top ; body blotches usually widened 



transversely, not conspicuously longer than wide catenatus tergeminus 



Head without distinct markings, uniform gray or stippled with brown ; 

 canthus rostralis not distinct ; rostral low, tapering to a point as it 

 curves backward between internasals ; body blotches conspicuously 

 longer than wide ravus 



•SISTRURUS CATENATUS TERGEMINUS (Say)i« 



Crotalus tcrgeminns Sat, Long's Expedition to the Rocky Mountains, vol. 1, 



1823, p. 499. 

 Sistrui'us catenatus tergeminus Klauep:r, Qcc. Pap. San Diego Soc. Nat. Hist, 



No. 1, 1936, p. 6.— Gloyd, Spec. Publ. Chicago Acad. Sci., No. 4, 1940, pp. 



36-44, pi. 2, map 1. 



Type. — Lost. 



Type locality. — Indefinite. 



Range. — "From southeastern Arizona, the Valley of the Rio Grande 

 and the Gulf Coast of Texas, north through southeastern Colorado 

 and central Oklahoma to eastern Kansas and southeastern Nebraska" ; 

 probably extreme northern Mexico, from Tamaulipas to Sonora. 



SISTRURUS RAVUS (Cope) 



Crotalus ravus Cope, Proc. Acad. Nat. Sci. Philadelphia, vol. 17, 1805, p. 191. 

 8istru7tis ravus Boulengek, Catalogue of the snakes in the British Museum, vol. 



8, 1896, pp. 571-572.— Gi.OYD, Spec. Publ. Chicago Acad. Sci., No. 4, 1940, 



pp. 06-59, pi. 4, fig. 1, map 3. 



Type.— U.S.lii.M. Nos. 25050-1, cotypes. 



Type locality. — "Table land of Mexico." 



Range. — Southern portion of the Mexican Plateau, central Hidalgo 

 to central Oaxaca, central western Veracruz to Morelos (recorded 

 from the states of Mexico, Morelos, Oaxaca, Puebla, Tlaxcala, and 

 Veracruz, and from Distrito Federal ) . 



' F'rom Gloyd, op. cit., pp. 20—21. 



^" Definite records of this race in Mexico are lacking ; there are several vague Mexican 

 records from Durango. Sinaloa, Sonora, and Tamaulipas (c/. Gloyd, op. cit., p. 41, and 

 Stejneger, Copeia, 1940, pp. 204-205 ; Jan, Elenco sisteniatico degli Ofidi, 1SG3, p. 124, 

 and Iconographie ggn^rale des ophidiens, livr. 46, 1874, pi. 3, fig. 6 ; Martin del Campo, 

 Anal. Inst. Biol. Mex., vol. 6, 1935, p. 295). 



