REPTILES 233 



di Size large; markings distinct C. atrox. 



di Size small; markings usually obscure f . mitchcUi. 



C2 With a middorsal series of separated rounded blotches. 



di A pair of horns between the eyes C. cerastes. 



do No such horns present. 



ei In the western prairie and Great Plains regions.. C. confluenies. 

 eo In the southwestern and Pacific States, 

 fi Along the Mexican border. 



gi Body with black rings at wide intervals C. lepidus: 



g2 Body with 2 series of brown dorsal blotches. . C. pricei. 



fo In the extreme southwest C. tigris. 



U On the Pacific slope C. oregonns. 



C. horridus L. Common rattlesnake (Fig. 127). Length 1,000 mm.; 

 tail 130 mm.; greatest length 1,750 mm.; color yellowish brown, with 

 about 22 wide, dark brown, more or less irregular cross bands, each of 

 which is often broken into 3 separate irregular blotches; abdomen 

 yellowish, with black spots; melanistic coloring not uncommon; tail 

 of adult black; scales in 23 to 25 rows; upper labials 

 13 or 14: entire country east of the Rockies; north- 

 ward to Maine; southward to northern Florida; in 

 ^^%^^J^^^ rocky regions, feeding on rodents and birds; bite 

 1^^^?^ very dangerous. 



Fig. 127. — Crolalus horridus {from Cope). 



C.adamanteusBesiUYois. Diamond-back rattlesnake. Length 1,800 

 mm.; tail 220 mm.; diameter of body 100 mm.; greatestlength 2,500 mm.; 

 color ohve or brown, with a dorsal series of about 20 more or less irregular 

 diamond-shaped markings, each diamond enclosing the ground color; 

 tail ringed with black; belly yellow; scales in 27 to 29 rows; upper labials 

 15: Atlantic and Gulf coastal regions, from North Carolina to Louisiana 

 and Arkansas; in swamps and wet woods; the largest American poison- 

 ous snake. 



C. atrox Baird & Girard. Length 1,300 mm.; tail 150 mm.; color 

 gray with a dorsal series of brown, diamond-shaped spots, each bordered 

 with white; scales in 27 rows; upper labials 15 or 16: Texas to Arizona, in 

 arid regions; common. 



C. molossus B. &. G Length 1,000 mm.; tail 80 mm.; color sulphur 

 yellow, with a dorsal series of brown rhombs open at the side; tail black; 

 scales in 29 rows: southern Texas to southern Arizona. 



