PfiRYNOSOMA. 389 



irregular, and imbricated scales. Neither dorsal nor caudal crests. 

 Abdomen protected by subrhombic scales, either smooth or keeled. 

 Limbs rather short. Tail about the length of the body or shorter, 

 depressed and broad at the base, subconical and tapering posteriorly. 

 Femoral pores present ; preanal pores wanting. 



SYN. Phrynosoma, WiEGM. in Oken, Isis, XXI, 1828, 367; &, Herp. Mex. 1, 1834, 

 18 & 52. WAGL. Naturl. Syst. Amph. 1830, 145. GEAT, Synops. Rept. in Griff. 

 Anim. Kingd. IX, 1831, 44 ; &, Catal. Lizz. Brit. Mus. 1845, 227. DOM. & BIBR. 

 Erpet. gen. IV, 1837, 311. HOLBR. N. Amer. Herp. II, 1842, 85. FITZ. Syst. Rept. 

 I, 1843,78. DOM. & A. DOM. Catal. meth. Rept. Mus. d'hist. nat. i, 1851, 78. GKD. 

 in Stansb. Expl. Vail. Gr. Salt Lake, Utah, 1852, 354. HALLOW, in Sityr. Rep. 

 Exped. Zuni and Color. Rivers, 1853, 119. 



OBSERV. There is no group in the Saurian order that may so 

 readily be distinguished as that of Phrynosoma. A body more or 

 less circular in shape, always depressed, sometimes flattened, scattered 

 all over with irregular and spine-like shields, in the midst of small and 

 irregular scales ; a solid and subtriangular head, provided with acute 

 spines or tuberculous knobs ; a short and conical tail, covered with 

 scales similar to those of the body, sometimes even more prominent, 

 are as many conspicuous features, which must strike any one at the 

 very first glance. The general aspect of these reptiles, mayhap their 

 sluggishness, will recall to rnind a frog or a toad : hence, the vernacu- 

 lar appellation of horned toads or horned frogs. The naturalist, how- 

 ever, with no hesitation, recognizes in them true Saurians, inasmuch 

 as the body, instead of being smooth, like that of either toads or frogs, 

 is covered, as just stated, with scales of a peculiar type. Besides the 

 spines of the head, the tail, although short, is another feature by which 

 they differ from both toads and frogs. So much when these animals 

 are at rest : so soon as they move, the observer cannot fail to be struck 

 with the fact that Phrynosoms never jump or leap, as is the case with 

 the Batrachians, to which they have been compared. 



If we look now more closely at the zoological peculiarities of the 

 group of Phrynosoma, we will observe that the vertex is a prominent 

 region of the head, subtriangular or cordiform, with a sharp and pro- 

 jecting margin, forming a ridge, overlapping the orbits; sometimes, 

 it is provided posteriorly with two spines, one at each angle. The 

 occipital region generally exhibits the largest spines in those species 

 in which they exist as a conspicuous feature. The temporal region 



98 



