SCELOPORUS UNDULATUS. 



The scales are comparatively well developed, larger on the back 

 than on the sides ; all of them, those on the neck as well as on the 

 body and limbs, being rhomboid ; they are imbricated, keeled, poste- 

 riorly acuminated by the extension of the keels. Those of the 

 dorsal region are entire upon their margin, and disposed upon ten or 

 eleven longitudinal series ; whilst on the sides, they are more or less 

 denticulated or serrated : their free margin being, at all events, pro- 

 vided with three points, a middle one, which is the largest, and one 

 on each side. The upper caudal scales are subquadrangular, some- 

 what oblong, -provided, in the direction of their length, with an 

 oblique keel, which terminates in a rather strong point. The infe- 

 rior caudal scales, which are likewise carinated and acuminated, 

 resemble in shape an isoceles triangle all along the conical and slender 

 portion of the tail ; whilst under its base and thickened portion, they 

 assume a rhombic form, having their margin serrated in the manner 

 already alluded to. 



The throat is covered with rather large and rhomboid, very thin, 

 smooth, imbricated, and posteriorly notched scales, except over the 

 chin and sides of the jaws, where they are considerably smaller; on 

 the pectoral and abdominal regions, they are equally smooth, though 

 somewhat larger, and posteriorly tricuspid ; under the limbs, they are 

 rhomboid, keeled, provided posteriorly with two or three small needles. 

 The fingers and toes are covered above and sideways with small, rhom- 

 boid, and slightly keeled scales, whilst the lower surface is protected 

 with broad, quadrangular, and tricarinated plates. 



There are about fourteen conspicuous femoral pores on either side, 

 perforating the posterior portion of a quadrangular shield. 



The ground color of the upper regions, in either sex, may be of a 

 greenish-grey, bronze, or coppery hue, generally unicolor in the male, 

 and transverse, undulating, blackish bands in the female. These bands 

 are either continuous or interrupted upon their middle, and bordered 

 posteriorly with fawn, yellowish, or whitish. The upper surface of 

 the head exhibits three transverse black streaks : one across the fron- 

 tal region, another across the orbital region, and the third along the 

 posterior edge of the occipital plates. The upper surface of the limbs 

 is barred with blackish to the very tip of the fingers. A black streak 

 often extends from the orbit across the temporal region and auricular 

 aperture, along the neck to the shoulder. The axillar and inguinal 

 regions, and the sides of the abdomen also, are dotted with black, or 



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