SCELOPORUS UNDULATUS. 379 



The male sex is to be distinguished from the female by two rather 

 large, concave plates, or scutellae, situated immediately behind the 

 external opening of the cloaca. 



1. SCELOPORUS UNDULATUS, Wiegm. 

 (Plate XIX, figs. 15-21.) 



SPEC. CHAR. Parietal plate smaller than the vertex plate. Two or 

 three unequal lorals. Temporal scales moderate, obtuse. Upper 

 labials exiguous ; two series of supralabials, the uppermost largest, 

 irregular, elongated, the inferior ones being still more exiguous 

 than the upper labials themselves. Lower labials somewhat larger 

 than the upper; infralabials smaller than the lower labials, and 

 disposed upon one series and a half. Preanal scales small, poste- 

 riorly acuminated, or emarginated. Postanal scales moderate, keeled, 

 acuminated. Posterior aspect of the thighs covered with blunt, 

 keeled, very small scales. 



SYN. Lacerta undulala, Bosc. MSS. 



Stellio undulatus, LATR. Hist. nat. Kept. II, 1802, 40. 



Agama undulata, BAUD. Hist. nat. Kept. Ill, 1805, 384. HARL. Journ. Acad. Nat. 

 Sci. Philad. VI, 1829, 13. 



I'r'imastix undulatus, MERR. Tent. Syst. Amph. 1820, 57. 



Lacerta hyacinthina, GREEN, Journ. Acad. Nat. Sci. Philad. 1, 1818, 349 & 405 (male). 



Lacerta fasciata, GREEN, Journ. Acad. Nat. Sci. Philad. 1, 1818, 349 & 406 (female). 



Tropidolepis undulatus, Cuv. Eegn. Anim. 2d ed. II, 1829, 38. GRAY, Synops. 

 Kept, in Griff. Anim. Kingd. IX, 1831, 43 ; &, Catal. Lizz. Brit. Mas. 1845, 208. 

 DCM. & BIBR. Erpet. gen. IV, 1837, 298. HOLBR. N. Amer. Herp. Ill, 1838, 51. 

 PI. vin ; &, 2d ed. II, 1842, 73, PI. ix. DUM. & A. DOM. Catal. meth. Kept. Mas. 

 d'hist. nat. i, 1851, 76. 



Sceloporus undulatus, WIEGM. in Oken, Isis, 1828, 369 ; &, Herp. Mex. I, 1834, 

 48. FITZ. Syst. Kept, i, 1843, 75. 



DESCR. The head is depressed ; the snout very obtuse, and the 

 interocular region very slightly convex, declivous from the frontal 

 region to the apex of the snout. The rostral plate is subtriangular, 

 quite developed transversely, and rather low. The nostrils are circu- 

 lar, perforating a small plate, separated from the rostral by a still 

 smaller plate, situated immediately in advance and inwardly of the 



