R. Zweifel 1953 Cnemidophorus sacki Rio Nazas at San Salvador, Durango, Mexico July 6 Small gular scales (all excepting the enlarged series adjacent to the infralabials) reddish brown. Chest and inner side of fore leg very dark blue, almost black. Blue persists over entire venter and inner surface of hind legs in largest individuals, becoming lighter posteriorly. Pattern of light lines barely visible in two of the three adults available, not distinguishable in the others. Light spot on hind leg yellow. Tail bluish-green. In sandy areas bordering the river in mesquite-ocotillo desert. Lizards were usually seen in shade of cottonwoods & tamarisks within a few feet of the water.