CHECKLIST OF THE SNAKES OF MEXICO 189 



blotches formed by brown punctations on a pink, buff, or gray back- 

 ground tigris 



30. Blotches of dorsal pattern bordered by a row of light unicolored scales ; 

 dark postorbital stripe extending backward to angle of mouth ; proximal 

 tail rings usually of same color as posterior body blotches, distal ones 

 usually black ; upper half of basal segment of rattle black, lower half 



light scutulatus scutulatus 



Blotches of dorsal pattern without light bordei-s ; dark postorbital stripe 

 not extending more than halfway to angle of mouth; tail rings all of 

 same color as posterior body blotches, distal ones not black ; basal seg- 

 ment of rattle without black on upper half scutulatus salvini 



CROTALUS ATROX Baird and Girard 



Crotalus airox Baied and Girard, Catalogue of North American reptiles, 1853, 

 pp. 5-6.— Gloyd, Spec. Publ. Chicago Acad. Sci., No. 4, 1940, pp. 204-206, 

 map 16, pi. 20, fig. 2. 



Caudlsona atrox so7ioraensis Kennicott,^ Proc. Acad. Nat. Sci. Philadelphia, 

 vol. 13, 1861, pp. 206-207 (type locality, "Sonora and vicinity"; no type). 



Type.—U. S. N. M. No. 7761. 



Type Jocallty. — Indianola, Calhoun County, Tex. 



Range. — "Desert, plains, and foothill areas from southeastern Cali- 

 fornia to west-central Arkansas, south to central Mexico including: 

 desert areas of Riverside, Imperial and extreme eastern San Diego 

 Counties, Calif.; the southern tip of Nevada; western and southern 

 Arizona (west and south of the Central Plateau) ; central and southern 

 New Mexico; all of Texas west of Long. 95°, except the Panhandle; 

 southern and west-central Oklahoma; western and central Arkansas; 

 extreme northeastern Baja California; nearly all of Sonora, Chihua- 

 hua, Coahuila, Nuevo Leon, Tamaulipas, and San Luis Potosi [west- 

 ern Hidalgo *] ; probably northeastern Durango and northern Zaca- 

 tecas [possibly northern Veracruz] ; Tiburon Island in the Gulf of 

 California." ^ 



CROTALUS BASILISCUS (Cope) 



Caudisona hisilisca Cope, I'roc. Acad. Nat. Sci. Philadelphia, vol. 16, 1864, p. 166. 

 Crotalus basiliscus Cope, in Yarrow, Wheeler's Rep. Geogr. Geol. Expl. Surv. W. 



100th Mer., vol. 5, Zool., 1875, p. 532.— Gloyd, Spec. Publ. Chicago Acad. Sci., 



No. 4, 1940, po. 142-141), map 10, pi. 16, fig. 1. 



" i'ossibly represents a race distinct from other populations of the species. 



* In Hidalgo it is known from Huaxteca Potosina and Tasquillo ; Dugfes's Zacatecas record 

 (1869, 1877) was later (1896) reforred to scutulatu:-:. 



5 We believe, without being certain, that the Tehuantepec record (Hartweg and Oliver, 

 Misc. Publ. Mus. Zool. Univ. Michigan, No. 47, 1940, pp. 29-30) rests upon some error 

 or an accidental dispersal. Much subsequent work in that region has revealed no more 

 specimens, and it may be added that the local residents, more than casually observant, 

 recognize only one species (d. durissus). The very complete conformity of the specimens 

 said to be from Tehuantepec with typical, northern specimens also throws great doubt upon 

 the actual existence of a well-established population on the Isthmus. Woodbury and 

 Woodbury (Journ. Washington Acad. Sci., vol. 34, 1944, p. 372) record another specimen 

 from Tehuantepec. Rattlesnake distribution in Mexico is distinctly disturbing ; unpub- 

 lished records held by Kauffeld add other incomprehensible distributional data. As a 

 means of explanation the agency of man in the production of these unusual records should 

 not be underestimated. 



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