62 UNIVERSITY OF COLORADO STUDIES 



with very fine papillae which give it a velvety appearance; tongue thick 

 and only free from the floor of the mouth at the tip. 



Family Iguanidae (page 62). 

 AA. Scales on dorsal parts very small and granular; ventral parts with large 

 plates; anterior portion of the tongue free from the floor of the mouth; 

 considerable of the surface of the tongue covered with scalelike papillae; 

 tip of the tongue deeply forked. . . Family Teiidae (page 76). 

 AAA. Scales on both dorsal and ventral parts smooth, polished and highly lus- 

 trous; anterior portion and sides of the tongue free from the floor of the 

 mouth; considerable portion of the surface of the tongue covered with 

 scalelike papillae; tip of the tongue only slightly notched. 



Family Scincidae (page 78). 



Family Iguanidae 

 The Iguanas and the Iguana-like Lizards 

 A very large family of lizards, particularly abundant in tropical 

 and subtropical America, although the family is represented in the 

 East Indies. Seven genera of this family have been reported from 

 Colorado and five of these are known to be more or less abundant in 

 the state. The other two stand on uncertain records. 



A. Body elongate, its width always much less than the length of the tail; 

 posterior margin of the head without bony "horns"; lateral margins of 

 the body without rows of large, pointed, elevated scales. 

 b. A median dorsal row of large, strongly keeled scales, elevated into a 



dorsal crest Dipsosaurus Hallowell (page 63). 



bb. No such row of elevated scales in the mid-dorsal region. 

 c. Ear opening exposed. 

 d. A gular fold. 



e. Occipital plate larger than either nasal plate, separated 

 from the rostral region by not more than ten plates; plates 

 on the top of the head large and irregular. 



Uta Baird and Girard (page 64). 



ee. Occipital plate equal to or smaller than either nasal plate, 



separated from the rostral region by at least twelve plates; 



plates on the top of the head small, and much alike in size 



and shape. . . Crolaphylus Holbrook (page 65). 



dd. No gular fold. . . . Sceloporus Wiegmann (page 67). 



cc. Ear opening covered. . . Holbrookia Girard (page 70). 



AA. Body depressed and robust, length of the tail equal to or usually less than 



the maximum width of the body; head with bony "horns" in the occipi- 



