120 VENOMS 



Colour green, spotted with yellow ; a black streak on the temple ; 

 belly greenish-yellow. 



Total length, 825 millimetres ; tail 145. 

 Habitat : Guatemala. 



(c) Sistrurus. 



Head very distinct from neck, covered above with nine large 

 symmetrical shields ; eyes rather small, with vertical pupils. Body 

 cylindrical; scales keeled, with apical pits; tail short, ending in 

 a segmented horny apparatus (rattle), producing a special sound; 

 subcaudals all or the majority in a single row. 



(1) S. ifiiliarius (Ground Kattle-Snake). — 9 — 11 supralabials ; 

 scales in '21 or 23 rows, strongly keeled ; 127 — 189 ventrals ; 27 — 36 

 subcaudals ; rattle short, consisting at the most of 10 segments. 



Colour greyish, yellowish, or brown, the vertebral line often 

 orange ; two undulating dark stripes from between the eyes to the 

 occiput, the enclosed space usually orange ; belly whitish, spotted 

 with dark brown or black. 



Total length, 520 miUimetres ; tail 70. 



Habitat: South-eastern North America, from North Carohna 

 to Texas. 



(2) S. catenatits (Prairie Rattle-Snake, or Massasanga, fig. 71). 

 — Two or three series of scales between the eye and the labials ; 

 11 — 14 supralabials ; scales in 23 or 25 rows ; 13(3 — 153 ventrals ; 

 20 — 31 subcaudals. 



Colour the same as in .S. iiiiliariiis ; a dark spot on the parietal 

 shields. 



Total length, 680 miUimetres; tail 80. 



Habitat : Great Lakes district ; United States east of the 

 Rocky Mountains and west of the Mississippi ; Northern Mexico. 



(3) S. raous. — 11 or 12 supralabials ; scales in 21 or 23 rows ; 

 147 ventrals ; 26 subcaudals. 



Colour yellowish-brown, with a dorsal series of dark brown 



