140 • P H I D I A. 



Spec. Char. — Scales disposed upon nineteen longitudinal series. 

 Ground color olivaceous, maculated with black. 



Stn. — Callirhinuspatagomensis, (jrRT).mVroc. Acad. Nat. Sci. Philad. August, 1857, 

 p. 182. 



Descr. — The head is but moderately elongated, depressed, flattened 

 upon the occipital region, and slightly declivous forwards upon the 

 frontal region. Yiewed from above its shape is subovoid or sub- 

 elliptical ; the temporal region passing gradually to the neck, which 

 is more slender than the body. The snout is subconical, and protrudes 

 beyond the lower jaw. The cleft of the mouth is ascending towards 

 its angles. The occipital plates are broadly developed, a little longer 

 than broad anteriorly, and tapering considerably. The vertex plate 

 is as long as the occipitals, maintaining its width posteriorly, where 

 it is subangular ; its sides being slightly concave. The supraoculars 

 are likewise well developed, being as long as the vertex plate and but a 

 little narrower anteriorly than posteriorly ; they are slightly concave 

 laterally. The frontal plates are subangular, the postfrontals being 

 larger than the prefrontals. The rostral is elevated, subpyramidal, 

 concave beneath. There are two well-developed and elevated nasals, 

 with the nostril between them, encroaching more upon the postnasal. 

 We observe two quadrangular loral plates, the uppermost being the 

 smallest of the two; its presence prevents the postfrontal from 

 advancing much to the side of the snout. There is but one ante- 

 orbital, quite narrow inferiorly, widening towards the supraocular 

 ridge, hence sending a triangular process to the upper surface of the 

 head, between the supraocular and the postfrontal. The postorbitals 

 are two in number, the upper one being the largest of the two. The 

 temporal shields, six in number, are conspicuous ; the anterior one is 

 the largest. There are seven well-developed upper labials, increasing 

 in size from the first to the sixth inclusively ; the seventh is larger 

 than the fourth; the third and fourth enter into the orbit. The 

 symphyseal is acutely triangular, and inclosed by the first pair of 

 inferior labials, which are elongated and sub-lanceolated. We observe 

 ten inferior labials, increasing in size from the second to the sixth ; 

 the others diminish posteriorly, being horizontally elongated, instead 

 of vertically ; the tenth is the smallest of all. There are two pairs 

 of mental shields, nearly equal in length, but the anterior pair is 

 broader and consequently larger. Elongated scale-like shields occupy 

 the region of the throat. 



