Hurter — Herpetology of Missouri. 129 



Key to Genera of Iguanidae. 



Ear without strong denticulation and neck without spinose tuber- 

 cles. Superciliaries imbricate. Tail long and tapering. 



Crotaphytus. 

 No complete transverse gular fold. Sceloporics. 



Head with large spines posteriorly. Phrynosoma. 



Genus crotaphytus. 



Head and body somewhat depressed and much shorter than the 

 tapering tail. All of the head plates are small. The labials not im- 

 bricated. The ear-opening is large, without strong denticulation. Dor- 

 sal scales small and nearly uniform. Long series of femoral pores 

 and one or more transverse gular folds are present. There are no 

 spinose tubercles on the neck. The superciliaries are imbricated. 

 Males with enlarged post-anal plates. 



36. Crotaphytus collaris Say. Collared Lizard. Bull 

 Lizard. Mountain Boomer. 



Agama collaris, Liosaurus collaris. 



Description. — -Head very broad, its width fully equal to the distance 

 from snout to ear. The head is much depressed and very distinct 

 from the neck, especially in the males. Nostrils large, turned upwards 

 and outwards, a little nearer to the end of the snout than the orbit. 

 Ear-opening large, vertically reniform. Scales on the snout a little 

 enlarged, irregular, convex; a series of enlarged supraorbital scales, 

 forming a letter X between the orbits; the two middle scales fused to- 

 gether, forming there only one row. Tongue narrow, slightly notched 

 at the tip, where it is free at the sides. Palatine teeth. Cheek teeth 

 compressed with three-lobed crown behind; conical anteriorly. The 

 bases apparently in a shallow groove. 



Supraocular scales small; back of the head with small granules. 

 Labials very small. A series of enlarged infra-orbital scales, very vari- 

 able in number and size; the median one sometimes much elongate, 

 owing to the fusion of two, or three scales. Throat covered with small 

 granules, which are slightly enlarged and flat in front of the gular fold. 

 Sides of neck strongly plicate. Dorsal scales uniform, small, juxta- 

 posed granules; ventral scales larger, flat, hexagonal. Limbs long; hind 

 limb reaches to the eye or to the tip of the snout; digits rather long. 

 Seventeen to twenty femoral pores on each side. Tail slender, cylin- 

 drical, nearly twice as long as head and body, covered with uniform, 

 small, smooth or feebly keeled scales. 



Color. — Upper parts of a variable shade of dark green or bluish; the 

 thigh, back, and sides marked pretty regularly and closely with round 



