70 PHRYNOSOMADOUGLASSII. 



largest. The inferior and external border of the lower jaw presents a series of 

 tubercles, those in front smaller and smooth, swelling only a little in the centre, 

 to give a festooned appearance, while those under the angle of the mouth are 

 larger, and slightly elevated into a pointed tubercle. Between this series of 

 tubercles and the labial plates, are interposed four or five rows of small scales. 

 The chin is covered with small, smooth, rhomboidal scales, of equal size. 

 There are nine small tubercles, which surround the posterior and superior part 

 of the head, extending from the point of one meatus of the ear to the other. 

 These tubercles are disposed as in the Phrynosoma cornuta, yet are so slightly 

 developed as not to deserve the name of spines, for none of them exceed two lines 

 in length, and the central tubercle is so small as hardly to be distinguished; thus 

 the posterior part of the head loses that spiny appearance so remarkable in the 

 Phrynosoma cornuta and Phrynosoma coronata. The entrance to the external 

 meatus of the ear is sub-triangular, large above, smaller below. 



The neck is short, contracted at the back of the head, and covered above with 

 small scales, and small, slightly elevated pointed trihedral tubercles. The scales 

 of the throat are smooth and very small; the skin presents a transverse fold, 

 which terminates on the side of the neck, over a deep depression in front of the 

 anterior extremities, and here the margins of the fold are furnished with small 

 pointed spines. 



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

 and is protected by small scales, interspersed with trihedral pointed tubercles, less 

 elevated than in the three other species, and arranged in four irregular rows on 

 each side of the vertebral hue, and surrounded at their bases by smaller tubercles 

 of similar form. The vertebral line diflfers here also from the P. cornuta and P. 

 orbiculare in having several tubercles interposed in the five or six rows of scales 

 that cover it. The flanks are furnished with only a single row of spines, that 

 give the serrated margin. The thorax and abdomen are covered with smooth 

 rhomboidal scales. 



