98 PHRYNOSOMA CORONATA. 



twelve inferior labial plates, quadrilatei'al, and still smaller than the superior. 

 The outer and inferior margin of the lower jaw presents an horizontal series of 

 large tubercles, increasing in size from the chin towards the angle of the mouth; 

 the posterior of these is a little removed from the row, and is much larger, sharply 

 pointed, and placed directly under the angle of the mouth; the other tubercles are 

 not elongated and spinous posteriorly, as in the Phrynosoma cornuta, but give 

 only a festooned appearance to the lower jaw. Between these tubercles and the 

 inferior labial plates are three or four roAvs of small scales. 



The chin is covered below, on the mesial line, with one or two rows of small 

 rhomboidal scales; on each side of these are placed four rows of larger scales, 

 greatly elongated, and pointed outwardly and posteriorly, reaching to the throat, 

 and increasing in size from within outwards, the external largest. Beyond these, 

 and within the series of large tubercles that border the lower jaw, are again three 

 or four rows of small scales. 



The whole posterior border of the head, from one angle of the raouth to the 

 other, is surrounded by a row of long pointed spines, of conical shape, flattened 

 at their bases, and disposed as in the Phrynosoma cornuta, but longer, and more 

 numerous — in general eleven, but I have seen thirteen, the inferior very small. 

 The external meatus of the ear is large, oval, and vertical. The neck is short, 

 contracted behind the head, and protected above by small scales and pointed 

 tubercles. The throat is covered with smooth rhomboidal scales, pointed poste- 

 riorly; a transverse fold of the skin ascends on the side of the throat, and covers 

 a depression in front of the anterior extremities, where the border of the fold is 

 furnished Avith spines. 



The body is short, flattened, rounded, and arched outwards at the flanks; above 

 it is protected by small, irregular scales, intermingled with large trihedral pointed 

 tubercles. These pointed tubercles are surrounded at their bases by others of the 

 same form, but smaller, and are irregularl}' disposed in four rows on each side of 

 the mesial line, as in the Phrynosoma cornuta, from which, however, it differs 



