234 VERTEBRATE ANIMALS OF THE UNITED STATES 



C. cerastes HoUowell. Sidewinder. Length 480 mm.; tail 50 mm.; 

 a pair of conspicuous horn-Kke projections between the eyes; color hght 

 brown, with a middorsal series of about 40 brown square spots and a 

 lateral series of small spots on each side; scales in 21 rows; upper labials 

 12: deserts of southern Utah and Nevada, Arizona and eastern Cali- 

 fornia; the popular name appHes to a curious sidewise method of 

 locomotion. 



C. mitchelli (Cope). Length 770 mm.; tail 87 mm.; color yellowish 

 or gray, spotted dorsally in a general rhomboidal pattern, often obscure; 

 scales in 23 or 25 rows; tail ringed with black: Arizona and southern 

 California. 



C. confiuentes Ssiy. Prairie rattler. Length 960 mm.; tail 100 mm.; 

 body rather slender; color yellowish brown or green, with a middorsal 

 series of about 40 irregularly rounded white-bordered brown blotches; 

 a pale band passes from beneath the center of the eye to the angle of 

 the mouth; scales in 25 to 27 rows; upper labials 14 or 15: the Great 

 Plains from western Iowa to the Rockies, and from Canada to Texas; 

 common, being frequently seen in prairie dog burrows, on the young of 

 which they feed. 



C. lepidus (Kennicott). Length 555 mm.; tail 50 mm.; color greenish 

 with black rings at wide intervals; scales in 23 rows; upper labials 12: 

 along the Mexican border of Texas, New Mexico and Arizona. 



C. pricei Van Denburgh. Length 525 mm.; tail 60 mm.; color gray- 

 ish brown, with 2 series of small brown blotches on the back; scales in 

 21 rows: southern Arizona. 



C. tigris Kenn. Length 650 mm. ; tail 50 mm. ; color yellowish gray, 

 with very indistinct blotches on the back and on the side, on the 

 hinder two-thirds of the body forming cross bands; scales in 23 or 25 

 rows; upper labials 14: southern CaHfornia, Nevada and Arizona. 



C. oregonus Holbrook. Length 860 mm.; tail 90 mm.; color light 

 brown, with a middorsal series of about 40 rounded or transverse brown 

 blotches, which become rings towards the tail; scales in 20 to 25 rows; 

 upper labials 15 or 16: entire Pacific Coast region, eastward into Idaho 

 and Utah. 



Order 4. Testudinata. — Turtles. Reptiles in which the body is 

 wide and short, and is enclosed in a shell composed of a dorsal shield, 

 called the carapace, and a ventral shield, the plastron. The shell, in 

 most cases, is formed of large external, epidermal, horny plates (tortoise 

 shell), which overlie internal bony plates. These latter consist, in the 

 carapace, of the flattened ribs and the flattened trunk vertebrae which 

 coalesce with overlying dermal bony plates, and are surrounded on 



