AMPHIBIA AND REPTILIA OF COLORADO 63 



tal and temporal regions; body with one or two rows of elevated, large 

 pointed scales on each lateral margin. 



f. Ear opening exposed. . . Phrynosoma Wiegmann (page 71). 

 ff. Ear opening covered with scales. . . Anota Hallowell (page 75). 



Genus DIPSOSAURUS Hallowell 



Dipsosaurus Hallowell, Proc. Acad. Nat. Set. Phila., Vol. VII, p. 92, 1854. 



But a single species of this genus is known, Dipsosaurus dorsalis 

 (Baird and Girard). 



Dipsosaurus dorsalis (Baird and Girard) 

 Desert Iguana or Keel-Backed Lizard 



Crotaphytus dorsalis Baird and Girard, Proc. Acad. Nat. Sci. Phila., p. 126, 

 1852. 



Dipsosaurus dorsalis — Yarrow, U.S.N.M. Bull. 24, p. 54, 1882 (Colorado); 

 Cope, Rept. U.S.N.M., p. 245, 1898 (Colorado). 



Gular fold present; head small, about equal to the hind foot in 

 length; femoral pores present; nostrils terminal, beyond the end of 

 the canthus rostratus; a mid-dorsal row of large, elevated, strongly 

 keeled scales; size moderately large; length ten to twelve inches. 



Color pale brown to brownish gray, shading into yellowish brown 

 in the caudal region; dorsal pattern of several narrow, irregular, 

 longitudinal, dark brown or black stripes; tail with dark cross bands; 

 ventral parts whitish or yellowish, without markings. 



This lizard feeds on plants, particularly flower heads. It is most 

 closely related to the tropical Iguanas of any of the North American 

 species. We have not examined specimens of this species from Colo- 

 rado, and the two records of it from this state are uncertain. If found 

 in Colorado it will probably be in the southwestern part of the state, 

 as this lizard ranges from Southern California to Arizona. Professor 

 A. E. Beardsley states that a large lizard answering the description of 

 Dipsosaurus dorsalis has been reported to him several times from 

 Lamar, Rocky Ford and Canon City, although he has never secured 

 specimens of it. 



This lizard is a desert species. 



