354 



S A U R I A. 



scales large and smooth. Sides of the neck coarsely granular. 

 Dorsal scales larger than the lateral and abdominal ones ; lateral 

 scales keeled; abdominal scales posteriorly rounded and entire. 

 Posterior aspect of thighs wholly granular. Yellowish-brown, with 

 a dorsal black line, on each side of which is a series of transversely 

 elongated, and oblique, blackish-brown spots, posteriorly white-mar- 

 gined ; sides variegated with brown and white. Beneath blackish- 

 grey ; chin and throat white-dotted ; abdomen unicolor. 



SYN. Tropidurus oxycephalus, WIEGM. in Nov. Act. Acad.nat. cur. XVII, i, 1835, 

 232. 



Liolaemus oxycephalus, GRAVENH. in Nov. Act. Acad. nat. cur. XVIII, n, 1838, 735. 

 PI. LIV, fig. 13. 



Rhytidodeira oxycephala, GRD. in Proc. Acad. Nat. Sci. Philad. November, 1857, 198. 



OBSERV. This species is allied to R. nigromaculata, from which it 

 chiefly differs by a narrower snout, more exiguous labials and supra- 

 labials, and entire abdominal scales, which are posteriorly rounded off. 



DESCR. The cephalic plates stand as follows : two pairs of inter- 

 nals, the anterior smaller than the posterior; two pairs of fronto- 

 nasals, a middle one, contiguous, in size and shape like the posterior 

 pair of internasals, and a smaller pair, situated exteriorly to the 

 former ; three pairs of frontals ; two prefrontal pairs : the middle one 

 largest, elongated, with two small subhexagonal interfrontals between 

 them, the foremost a little larger, and engaging somewhat between the 

 fronto-nasal, the external pair slender, exiguous ; the postfrontal paii % , 

 subpentagonal, and shorter than the middle prefrontals, are contigu- 

 ous, admitting slightly the hindmost interfrontal between the anterior 

 portion of their commissure ; a vertex plate, elongated, laterally sub- 

 concave, and posteriorly tapering ; four pairs of small subequal parie- 

 tals, the foremost contiguous, interposing between the vertex plate 

 and the middle occipital, the others diverging between the occipitals 

 and supraoculars ; a middle occipital, inclosed by the two anterior 

 pairs of parietals and a pair of rather well-developed postoccipitals, 

 contiguous upon their inner edge ; one pair of latero-occipitals, situated 

 sideways of the postoccipitals ; finally, a semicircular chain of small 

 transversely elongated plates interposes between the temporal scales, 

 on one hand, and the scales of the neck, on the other hand. 



Now, as to the supraoculars : the posterior four middle ones are 



