86 3. IGUANID& 



b'. Very large ; few if any caudals spinose; upper surfaces 

 very coarsely marked or blotched with blackish brown 

 and yellow, orange or red; scales in a caudal whorl not 

 fewer than 63 (63 to 76); ventral rows between 

 gular fold and anus 140 to 156. 



S. varius. p. 101. 



a*. Scales in a caudal whorl at largest part of tail not more 

 than 50 ; nuchal scales strongly spinose, largest larger 

 than largest scales on top of head, almost as large as 

 largest preauriculars; not more than 25 dorsals in a 

 head-length. 



bb. Scales on limbs less strongly keeled, often nearly 

 smooth on posterior surface of lower leg (tibia); 

 scales much less spinose on limbs and tail j most dorsal 

 scales not spinose ; adults mottled; size moderately 

 large j about 20 to 25 dorsals in a head length. 



S. slevini. p. 97. 



bb 2 . Scales on limbs more strongly keeled ; posterior sur- 

 face of lower leg with strongly keeled scales; scales 

 much more spinose on limbs and tail; nearly every 

 dorsal scale ending in a short spine; adults blackish, 

 nearly unicolor; size very large; about 15 to 20 dor- 

 sals in a head length. 



S. hispidus. p. 99. 



10. Sauromalus ater Dumeril 



Chuckwalla 

 Plates 3 and 4 



Sauromalus ater DUMERIL, Arch. Mus. Hist. Nat. Paris. Vol. VIII, 1856, 

 p. 536, pi. XXIII, figs. 3, 3a (type locality, unknown) ; COPE, Bull. 

 U. S. Nat. Mus., No. 1, 1875, p. 4-7; BOCOURT, Miss. Sci. Mex., 

 Kept., 1874, p. 14-9, pi. XVII bis., fig. 11; COUES, Surv. W. 100th 

 Merid., Vol. V, 1875, p. 600; YARROW, Bull. U. S. Nat. Mus., 

 No. 24, 1883, p. 51; BOULENGER, Cat. Lizards Brit. Mus., Vol. II., 

 1885, p. 202; COPE, Bull. U. S. Nat. Mus., No. 32, 1887, p. 35, 



