72 UNIVERSITY OF COLORADO STUDIES 



regarded as very dangerous by the Negroes in the southwest. They 

 depend upon their general appearance for protection, as they move 

 rather slowly. Their cephaUc horns are very effective as protective 

 structures in rendering them difficult to swallow. Cope^ records 

 finding a rattlesnake, which had died from attempting to swallow a 

 Phrynosoma, with the occipital horns forced through its skin. Strecker* 

 found a hawk dead from the same cause. 



Horned Lizards are found from Washington to Southern Mexico. 

 They range as far east as Missouri and Arkansas, being restricted to 

 the arid and semi-arid regions. 



The two species of this genus found in Colorado may be distin- 

 guished by the following key. 



a. One row of elevated, pointed scales along each lateral margin of the body; 



horns short P. hernandesi (Girard). 



aa. Two rows of elevated, pointed scales along each lateral margin of the 

 body; horns long and prominent .... P. cornutum (Harlan). 



Phrynosoma hernandesi (Girard) 



Hernandez's Horned Toad or Lizard (Figures 12 and 14) 



Tapaya hernandesi Girard, Wilkes U.S. Expl. Exped., HerpL, p. 395, 1858. 



Phrynosoma douglassii douglassii — Yarrow, Wheeler Survey, Vol. V, pp. 580 

 and 581, 1875 (Ft. Garland, Colorado Springs and Pagosa, Colo.). 



Phrynosoma douglassii hernandesi — Cope, Kept. U.S.N.M., p. 414, 1898 

 (Pagosa and Colorado Springs, Colo.). 



Phrynosoma hernandesi — Cockerell, Univ. Colo. Studies, Vol. VII, p. 131, 

 1910 (Meeker, Colo., and two miles southeast of Meeker, Colo.). 



Horns short, not exceeding the diameter of the eye in length; one 

 rather prominent horn projecting backward from the posterior end of 

 each canthus rostratus; three directed outward and backward from 

 the lateral angles of the head in the temporal region; a short horn on 

 each side of the occipital region, pointing backward and upward, and 

 a very small median occipital horn. 



One row of elevated, pointed scales on each lateral margin of the 

 body; dorsal scales irregular in size and shape, many elevated, pointed 



» Kept. U.S.N.M., p. 404. 1898. 



» Proc. Biol. Soc. Wash., Vol. XXI, p. 168, 1908. 



