44 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



This species lives in mountainous regions where they find many ledges, cleft 

 with many fissures and large shelving rocks. During the hibernating season they 

 gather together, coiling closely, and thus pass the winter. In the spring, during 

 the mating season, they linger on the main ledge in large numbers, but finally scatter 

 to the timber for the warm months. This is the most mild-tempered species and 

 becomes so docile that it can be handled like the harmless snakes. 



Crotalus atrox Baird and Girard. " Western Diamond Rattlesnake." 



Next to the diamond-back rattlesnake of the Southeastern States, this species 

 is the largest of the genus. It attains a length of 7 feet. Color-pattern similar to 

 the preceding species, except the tail, which is white with jet-black rings. The 

 ground-color may be yellowish-gray, pale bluish-gray, or pinkish, according to the 

 localities. General color-pattern much duller than the eastern species. Some 

 specimens from the desert region of Arizona are of distinct pinkish ground-color 

 with vividly white-rimmed rhombs. Tail chalky white with jet-black rings. It 

 mainly inhabits the sub-arid and desert regions of Texas and southwestern United 

 States. Common in central and western Texas, southern New Mexico, Arizona, 

 and southern California. In Mexico the coloration and scutellation of the head 

 differs from the original type. This is one of the wildest and most vicious species. 



Crotalus atrox var. scutulatus. " Mountain Diamond Rattlesnake." 

 Crotalus scutulatus Boulenger. 

 Irregular plates cover anterior portion of head, resembling Crotalus oregonus. 

 It is, however, maintained to be a subspecies of Crotalus atrox, which in the Mexican 

 Tablelands has undergone variation in some of the typical forms. Length about 

 3 feet. Arizona, New Mexico, Texas, northern part of Mexico. 



Crotalus atrox var. ruber Cope. " Red Diamond Rattlesnake." 



Differs from the typical atrox in having a more reddish hue. Length about 4.5 

 feet, but can grow up to 5 feet. Arid regions of California, and the peninsula of 

 lower California; southwestern Arizona. 



Crotalus confluentus Say. " Prairie Rattlesnake." 



Body not so stout as most rattlesnakes, and the snake seldom reaches a length 

 of 6 feet. Greenish-yellow, or olive, with a row of large, round, and well-separated 

 blotches of brown upon the back. Toward the tail the blotches fade into obscure 

 bands. The head marking differs from the Pacific rattlesnake. In the prairie 

 rattlesnake a dark band starts from beneath center of eye to angle of mouth, while 

 the Pacific rattlesnake has the dark band commencing behind center of eye. The 

 dark band is bordered with yellow strips — the front strip being narrow, the width 

 of one scale row, whereas the pale strip of the Pacific species is of the width of two 

 scale rows. 



This species is rather vicious and irritable, but becomes very tame in captivity. 

 In the prairie this snake often prowls into the burrows of prairie dogs, but instinc- 

 tively it seeks the deserted burrows. Sometimes the snake may be hunting in the 

 burrows to devour some of the young. 



Western parts of North America, from British Columbia (46° north latitude) to 



the southern parts of California, Dakota, Nebraska, Kansas, southwestern Texas, 



northern Mexico. 



Crotalus oregonus Holbrook. " Pacific Rattlesnake." 

 Crotalus lucifer Baird and Girard. 



Rather smaller than the prairie ratdesnake, but resembles it in most other char- 

 acters except head markings, of which mention has been made above. Habits similar 

 to the Prairie rattlesnake. Length under 4 feet. The Pacific region, from southern 

 British Columbia to southern California; also in Idaho, Nevada, and Utah. It 

 occurs in altitudes as high as 11,000 feet. 



