CHAPTER XVII: THE HORNED LIZARDS 



GENUS PHRYNOSOMA 



A Genus of Lizards that are Most Commonly Known as tie 

 Horned "Toads" 



FROM all the other genera of the North American Lizards, 

 the Horned Toads are very distinct. Their very wide, much- 

 flattened and toad-like bodies, the short tail and the develop- 

 ment among most of the species of sharp, conical horns upon 

 the back of the head and the temples are unique characters. 

 The scalation is also peculiar, as the back is covered with minute, 

 granular scales, among which rise, almost vertically greatly 

 enlarged and sharply-pointed scales, which are imbedded like 

 miniature pyramids at their bases. Altogether, these lizards 

 are so spiny in their general make-up as to appear quite formidable 

 to the observer uninitiated in their habits. 



The Horned Lizards are found only in the western portions 

 of the United States and in Mexico. The number of species 

 generally recognised is 17, of which 4 are exclusively Mexican. 

 Several other species occur commonly in Mexico and range but 

 a very short distance northward over the boundary line of the 

 United States. 



Owing to the fact that the ear drum of several species is 

 covered with a thin skin studded with minute scales, certain 

 writers have seen fit to place these in a separate genus Anoia. 

 This character appeals to the writer as too superficial for the 

 division of these peculiar lizards into two genera and he has 

 decided to include them all under the head of Plrynosoma. 



In studying the species of this genus, the following char- 

 acters should be observed, (i) The formations and propor- 

 tionate length of the head spines. (2) The character of the 

 spines upon the back and whether these are surrounded by a 

 rosette of smaller spines, at their bases. (3) The character and 

 number of rows (whether one or two) of fringes of spiny scales 



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