66 PHRYNOSOMACORONATA. 



than the superior. The outer and inferor margin of the lower jaw presents a 

 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 Phry- 

 nosoma cornuta, but give only a festooned appearance to the lower jaw. Between 

 these tubercles and the inferior labial plates are three or four rows 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 mouth 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 posteriorly; 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 borders of the fold is furnished with 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 irregularly disposed in four rows on each side of 

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

 entirely in wanting the three or four rows of small scales on the vertebral line, 

 in place of which it has large scales and spiny tubercles. The flanks are furnished 

 with a double row of spines; the upper is much the larger, and makes a serrated 



