THE PRINCIPAL SPECIES OF POISONOUS SNAKES 129 
Colour greyish-yellow to salmon-red, finely punctulated with 
brown, with a dorsal series of transverse darker spots; belly 
yellowish. 
Total length, 1,020 millimetres ; tail 90. 
Habitat : Desert regions of Southern California, Lower Cali- 
fornia, and Arizona. 
(8) C. triseriatus—9—13 supralabials; scales in 21—25 rows, 
dorsals strongly keeled ; 142—184 ventrals ; 22—30 subcaudals. 
Colour olive or brown, with a vertebral series of rather small 
dark brown spots edged with black and white; belly yellowish, 
spotted with dark brown, or dark grey-brown powdered with 
whitish. 
Total length, 530 millimetres; tail 55. 
Habitat : Mexico. 
(9) C. polystictus.—Closely allied to the foregoing, but 4 inter- 
nasals, 14 or 15 supralabials, and scales in 27—30 rows; 123—151 
ventrals ; 18—23 subcaudals. 
Colour yellowish-brown, beautifully marked with 6 or 7 longi- 
tudinal series of alternating, elongate, dark brown, black- and white- 
edged spots, separated by narrow interspaces of the ground-colour ; 
a pair of diverging dark bands on the top of the head, separated 
by a narrow pinkish-white streak; belly pinkish or yellowish, 
spotted with dark brown. 
Total length, 600 millimetres; tail 60. 
Habitat : Tableland of Mexico. 
(10) C. lepidus.—12 supralabials ; scales in 21 or 23 rows, dorsals 
strongly keeled; 153—169 ventrals; 24—31 subcaudals. 
Colour brown or greenish-grey, with dark brown or jet-black 
light-edged cross-bands, narrowing on the sides; two dark spots, 
or a V- or heart-shaped black marking on the nape; belly dirty 
white, spotted with brown. 
Total length, 350 millimetres ; tail 60. 
Habitat : Western Texas, New Mexico, Arizona, North Mexico. 
(11) C. cerastes (Horned Rattle-Snake; fig. 76).—Supraocular 
5) 
