48. CROTALUS 913 
back from the pit. The lower surfaces are white or pale 
yellow often clouded or mottled with gray or brown on the 
body, especially posteriorly and laterally. The tail both above 
and below is black or blackish brown, sometimes unicolor, 
but often with some lateral paler areas indicating cross- 
bands. 
Length to anus__.....-.... 615 796 800 896 905 1070 
Length of tail to base 
Obmrattle: sees ee 45 45 65 54 54 76 
Distribution—The area inhabited by this large species 
extends from Pecos and El Paso counties, Texas, west to 
Arizona, and south into northern Mexico. 
In Arizona, this rattlesnake 1s quite common in the Hua- 
chuca Mountains, in Cochise County, where it has been 
taken in Ramsey, Miller and Carr canyons. It has been 
collected also at an elevation of 5,000 feet near Blue River, 
Greenlea County, and at an altitude of 6,000 feet in Wal- 
nut Canyon, in the Santa Rita Mountains. Specimens are at 
hand from Saw Mill Canyon, Santa Rita Mountains, Pima 
County; trail between Gardner Canyon and Greaterville, 
Pima County; Tucson, Pima County; vicinity Pete Moun- 
tain, Santa Rita Range, Santa Cruz County; Fort Buchanan, 
Santa Cruz County; and from the canyon between Madera 
and Agua Caliente canyons, Santa Rita Mountains, Santa 
Cruz County, Arizona. The most northern record seems to 
be that of a specimen secured at Cave Creek, Maricopa 
County. Cope has recorded a specimen as taken by Dr. 
Mearns in the “Tucson Mountains, Yuma County,” probably 
an error for Pima County. 
Remarks.—This species is easily distinguished by its 
black tail and snout, and by the large plates on the anterior 
