Key to Lizards of Illinois

1a. Legs absent; a groove present on each side of the body from neck to vent … Slender Glass Lizard

1b. Four limbs present; no groove on side of body … 2

2a. Scales strongly keeled, making skin appear and feel rough … Eastern Fence Lizard

2b. Scales not keeled … 3

3a. Dorsal scales small and granular; venter with large transverse scales (fig. 20); dorsum with six longitudinal stripes; neck without black collar … Six-lined Racerunner

3b. Dorsal scales large and smooth … 4

large transverse scales
Figure 20. Ventral view of the Six-lined Racerunner showing large transverse scales

4a. Frontal scale not rectangular (fig. 21a); lower eyelids with a transparent “window”; snout-vent length less than 55 mm … Little Brown Skink

4b. Frontal scale more or less rectangular (fig. 21b); lower eyelids without a transparent “window”; snout-vent length greater than 55 mm … 5

Figure 21. Dorsal view of skink heads: (a) V-shaped frontal scale (f) of Little Brown Skink; (b) rectangular frontal scale (f) of other skinks

5a. One postlabial scale (fig. 22a); supralabial scales usually number 8 (fig. 22a) … Broad-headed Skink

5b. Two postlabial scales (fig. 22b); supralabial scales usually number 7 (fig. 22b) … Common Five-lined Skink

Figure 22. Side view of head: (a) Broad-headed Skink and (b) Five-lined Skink showing position of postlabial scales (pl) and position of supralabial scales (numbered)