184 VERTEBRATE AXIMALS OF THE UNITED STATES 



Key to the Species of Crotaphytus 



ai One or 2 rows of enlarged scales between the orbital area. 



bi A double black collar on the neck C. collaris. 



b2 No collar on the neck C. reticidatus. 



a2 Several rows of small scales between the orbital areas. 



bi Snout short, truncate in profile C. silus. 



h-i Snout longer C. wisUzenii. 



C. collaris (Say). Collared lizard; mountain boomer. Body short; 

 head very large ; length 300 mm. ; tail 200 mm. ; color green or gray, with 

 numerous white or yellow spots; behind the head are 2 black rings, 

 separated by a white or yellowish space ; throat usually orange : central 

 and southern Missouri to central California and southwards; north- 

 ward into Idaho and Oregon; in dry rocky places; omnivorous; often 

 abundant; it sometimes runs on the hind legs, like a kangaroo. 



C. reticulatus Baird. Similar to C. collaris 

 in form and size ; color yellowish brown or gray, 

 with a net-work of pale gray or yellow: south- 

 western Texas; rare. 



C. wisUzenii Baird and Girard. Leopard 

 YiG.io2.—Caiiisauriisven- lizard. Length 300 mm.; tail 210 mm.; color 

 brown, with black blotches and red dots; back 

 and tail with yellowish or red transverse bands: the Great Basin from 

 Idaho into southern California and Mexico, in desert places; abundant. 

 C. silus Stejneger. Similar to C. wisUzenii but with a shorter and 

 more truncate snout, and sharply defined light cross bands: San 

 Joaquin Valley. 



5. Callisaurus Blainville. Body stout; tail rather short; neck- 

 fold present: 4 species, i in the United States. 



C . ventralis {YiaXXoy^eW) . Gridiron-tailed lizard (Fig. 102). Length 

 180 mm.; tail 100 mm.; color gray or greenish, thickly spotted with 

 white; 2 rows of large spots on back; under surface of tail of male 

 white, with 4 wide black bars: western Texas to California; northward 

 into Utah and Nevada; in desert and arid regions; very common; when 

 running it curls its tail over its back. 



6. Uma Baird. Body rather stocky, with 2 rows of subdigital 

 scales, and a lateral digital fringe of elongate scales: i species. 



U. notata Baird. Length 220 mm.; tail 120 mm.; ground color 

 black, with numerous large round, white spots, each with a black 

 center; abdomen white, with a black spot on each side: deserts of 

 southeastern California. 



