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 dorsaV 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 oxycepJialus, Wiegm. in Nov. Act. Acad. nat. cur. XVII, i, 1835, 

 232. 



Liolaemus oxi/cephalus, Gravenh. in Nov. Act. Acad. nat. cur. XVIII, ii, 1838, 735. 

 PI. LTV, fig. 13. 



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



Observ. — This species is allied to H. nigromacidata, 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 pair, 

 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 



