No definite, lengthwise fold of skin along each side; back with rounded 

 or pointed scales 28. 



19. With four large scales (and several smaller ones) in a square arrange 



ment on top of the head in front of a line drawn between the front 

 corners of the eyes; Mexican Border 



Gerrhonotus imbncatus letncollis (Stejneger) Plated Lizard 

 (Barissia levicolUs Stejneger) 

 With three large plates in a triangular arrangement on top of the head 

 before the eyes 20. 



20. With a small median plate behind the rostral plate; belly obscurely mot' 



tied; Texas 



Gerrhonotus mfernaUs Baird Brown Alligator Lizard 

 With two small plates behind the rostral plate; belly often lengthwise 

 lined 2L 



2L Scales almost smooth above, quite so on the sides; dark cross bands on 

 back finely bordered by darker color; Ariz, and N. M. 

 Gerrhonotus Xingii Gray King's Alligator Lizard 

 (Gerrhonotus nobilis (B. ^ G.) ) 

 Scales weakly to strongly keeled; back and sides with spots or with dark 

 cross bands which may be finely light bordered posteriorly 22. 



22. Usually with dark cross bars across back and sides; eye yellow; usually 



with fourteen lengthwise dorsal scale rows 23. 



Central area of back often blotched, but seldom with dark cross bars; eye 



dark; with fourteen to sixteen lengthwise dorsal scale rows 25. 



23. Light areas across back betv^een the dark bars tinged with red in the 



mid-dorsal section; Gal. 



Gerrhonotus multicannatus multicarinatus (Blainville) 

 Red-backed or Keeled Alligator Lizard 

 Light areas grayish, untinged with red 24. 



24. With eight rows of scales on base of tail keeled; Pacific States 



Gerrhonotus multicarinatus scincicauda (Skilton) 

 Skink-tailed Alligator Lizard 

 With more than eight rows of scales on base of tail keeled; S. Gal. 

 Gerrhonotus mult:carmatus wehhii (Baird) 

 Webb's Alligator Lizard 



25. Scales on upper part of foreleg mostly smooth 26. 

 Scales on upper part of foreleg mostly keeled 27. 



26. Usually with fourteen complete lengthwise dorsal scale rows; tail dark 



spotted; Montana to Wash, and N. Gal. 



Gerrhonotus coeruleus principis (B. ^ G.) 

 Northern Alligator Lizard 

 Usually with sixteen complete lengthwise dorsal scale rows; tail dark 

 barred; adjacent mountain region of Oregon and Gal. 

 Gerrhonotus coeruleus shastensis Fitch 

 Shasta Alligator Lizard 



27. Sides usually light flecked; Gal. 



Gerrhonotus coeruleus palmeri (Stejneger) 

 Sierra Alligator Lizard 



367 



