The Horned Lizards 



b. Ear drum covered with granular scales. 

 Head spines rudimentary. Body spines little developed. 

 Colour pinkish or dull red. 



s.MooTH HORNED "toad," P. platyrhinum. 

 Division 11. Head spines well developed. 



a. Ear drum coi'ered with granular scales. 



t A single series of marginal, spiny scales. 



Size rather small; head proportionately small, with 



large, central spines directed upward. 



ASHY HORNED "toad," P. calidiarum. 

 tt Two series of marginal spiny scales, the lower but 



slightly developed. 

 Head spines moderate. No enlarged scales on central 



portion of chin. 



GOODe's HORNED "TOAD," P. goodci. 



Head spines large. Two rows of slightly enlarged scales 

 on central portion of chin. 



maccall's horned "toad," p. maccallii. 



b. Ear drum exposed. 



* A row of large, projecting plates beneath each 

 series of lower labials, and between these, two 

 double rows or triple rows of enlarged scales. 

 Head spines large, of regular arrangement. 

 One series of marginal spines. 



CERROS ISLAND HORNED "toad," P. cerroensc. 



Head spines large, of regular arrangement. Body 

 spines very bristling. Two series of marginal spijies, 

 of equal length. 



PACIFIC HORNED "toad," P. coroftatum. 



Four large central horns and three upon each temple, 

 forming a perfect circlet or crown upon the rear of 

 head. One large and one very small series of mar- 

 ginal, spiny scales on sides of body. 



REGAL HORNED "toad," P. regale. 



**A row of large, projecting plates beneath each series 

 of lower labials; between these, two single rows of en- 

 larged scales. 



Two large, central head spines, directed upward; 

 three temporal spines. 



TEXAS HORNED "TOAD," P. COmutUM. 



Concerning a name. — Thus far, in this chapter, the writer 

 has used freely the name "horned toad," but he realises how 

 inappropriate is that appellation in connection with a genus of 

 lizards. However, he feels, that to introduce the beginner to 

 any group of reptiles, it is best to employ a well-known, popular 

 title at the start. Now that we understand our subjects, let us 



147 



