490 MB. G. A. BOULENGEB ON THE [May 18, 



xxii. 1885, p. 395 ; Bouleng. Cat. Liz. ii. p. 226 (1885); Duges, La 

 Naturaleza, (2) i. 1889, p. 205. 



Trojncl -ilepis sinnosus. Gray, Griff. A. K. ix. Syn. p. 43 (1831); 

 Dum. & Bibr. Erp. Gen. iv. p. 304 (1837) : Gray, Cat. Liz. p. 209 

 (1845). 



Sceloponis Jiorridvs, Wiegm. Herp. Mex. p. 50 ; Bocourt, 1. c. 

 p. 178, pi. xviii. fig. 8 ; Cope, 1. c. p. 394. 



Tropidolepis horridits, Dum. & Bibr. t. c. p. 306 ; Gray, Cat. 

 p. 209. 



Sceloporm clarkii, Baird & Gir. Proc. Ac. Philad. 1852, p. 127, 

 and U.S. Mex. Bound. Surv., Eept. p. 5 ; Yarrow, Wheeler's Rep. 

 Explor. W. lOOth Mer. v. p. 575, pi. xxiii. fig. 1 (1875) ; Stejneger, 

 N. Amer. Faun. no. 3, 1890, p. 110, and no. 7, 1893, p. 178, pi. i. 

 fig. 1. 



Sceloporiis magister, Hallow. Proc. Ac. Philad. 1854, p. 93, and 

 Eep. TJ.S. Explor. Surv. E.. R. x. pt. i\\ p. 5 (1859) ; Stejneger, 

 N. Am. Faun. no. 7, 1893, p. 178, pi. i. fig. 2. 



Sceloporus Jforidanvs, Baird, Proc. Ac. Philad. 1858, p. 254 ; 

 Stejneger, 1. c. p. 181, pi. i. fig. 6. 



Sceloporus oligoporus. Cope, Proc. Ac. Philad. 1864, p. 177. 



Sceloporus thayerii (non B. & G.), Bocourt, 1. c. p. 175, pi, xviii. 

 fig. 5. 



Sceloporus spinosus, part., Giinth. Biol. C.-Am., Eept. p. 63 

 (1890). 



Scelojjonts boulengeri, Stejneger, 1. c. p. 180, pi. i. fig. 5. 



Head-shields smooth; frontal transversely divided (exceptionally 

 single), usually in contact with the interparietal, sometimes sepa- 

 rated from it by the frontopai-ietals or by a small azygous shield ; 

 interparietal as long as broad, a little longer than broad, or a little 

 broader than long, nearly as broad as or broader than the parietals ; 

 a series of three to five large, transverse supraoculars, which are 

 rarely broken up into two series as in S. torquatus y. jjoinsetti^ ; a 

 complete or incomplete series of scales on the inner side of the 

 enlarged supraoculars, the last or last two of which are sometimes 

 in contact with the frontoparietals or frontoparietals and parietals ; 

 one or two series of small scales between the large supraoculars 

 and the supraciliaries ; two canthal scales (exceptionally one) ; 

 three to six pointed scales on the anterior border of the ear, in 

 some specimens not larger than those in front of them, in others 

 larger and sometimes much longer than broad. 



Dorsal scales much larger than ventrals, as long as broad, 

 strongly keeled, mucronate, and usually denticulate, the keels 

 forming parallel series or, rarely, slightly converging towards the 

 median line ; 25 to 32 scales between the interparietal shield and 

 the base of the tail ; 5 to 7 scales, taken in the middle of the back, 

 correspond to the length of the shielded part of the head. Lateral 

 scales graduating into dorsals and ventrals, strongly keeled, directed 

 obliquely upwards and backwards. Ventral scales small, smooth, 

 bi- or tricuspid. 34 to 40 scales round the middle of the body. 



1 This is particularly marked in a specimen from Pueblft. 



