124 VENOMS 



segments fall off and are at once replaced Contrary to the belief 

 which was long entertained, their number bears no relation to the 

 age of the snake. 



Rattle-Snakes are met with especially in stony and arid 

 localities, or among brushwood near water. They hardly ever bite 

 except when surprised or attacked. 



(1) C. terrificus (Dog-faced Eattle-Snake, Cascavella in Brazil ; 

 fig. 73) . — Snout very short ; three or four series of scales between 

 the eye and the supralabial shields ; body-scales in 23 — 31 rows, 

 dorsals very strongly keeled ; 160 — 199 ventrals ; 18 — 30 sub- 

 caudals. 



Colour brown, with a series of darker, light-edged rhombs, 

 often lighter in the centre ; a dark streak from the eye to the 

 angle of the mouth ; belly yellowish-white, uniform or spotted with 

 brown ; tail generally brown or blackish. 



Total length, 1,320 milUmetres ; tail 130. 



Habitat : Arizona, New Mexico, and Texas to Southern Brazil, 

 and Northern Argentina. 



('2) C. scwiwZa^its (Texas Eattle-Snake ; fig. 74). — 13 — 16 supra- 

 labials ; scales in 25 or 27 rows ; dorsals striated and strongly 

 keeled ; 167—170 ventrals ; 18—20 subcaudals. 



Colour yellowish or greyish-brown, with a series of large dark 

 brown light-edged rhomboidal spots ; an oblique dark streak below 

 the eye ; belly uniform yellowish-white. 



Total length, 760 millimetres ; tail 65. 



Habitat: Arizona, New Mexico, Texas, North Mexico. ' 



(3) C. confluentus (Pacific or Mottled Eattle-Snake; fig. 75). 

 — Upper head-scales small, striated ; 13 — 18 supralabials ; body 

 scales in 25 — 29 rows, striated and strongly keeled ; 168 — 197 

 ventrals ; 17 — 34 subcaudals. 



Colour yellowish, greyish, or pale brown, with a dorsal series 

 of large brown or red spots, usually rhomboidal or transversely 

 elliptic in shape ; a light streak or triangular marking across the 

 supraocular shields ; belly yellowish, uniform or spotted with 

 brown. 



