52 HETERODON. 



Vertical plate hexagonal, narrower behind; longer than broad; 

 angles all distinct, lateral outlines straight. Postfrontal large, the 

 lateral angle extending down to the loral; the two postfrontals 

 separated anteriorly by the azygos or postrostral. Prefrontals 

 smaller, entirely separated by the azygos. Ptostral with the out- 

 line spherical angled, subacute at the apex, its upper surface com- 

 pressed into a sharp ridge, which, prolonged backwards between 

 the nasals and the prefrontals, connects with the azygos. This is 

 linear, subpentagonal, acute-angled behind, where it wedges between 

 the postfrontals. Superciliaries large. Scales behind the head 

 distinctly cariuated. Eye large. Line connecting tip of rostral 

 with the postinferior corner of the last labial passes over the lower part 

 of the eye. A triangular nasal, with the corners rounded, joined by 

 its apex to the exterior angle of the postfrontals. Nostrils valvular, 

 situated entirely in the posterior nasal, the anterior edge formed by 

 the anterior nasal. Labials 8 above, 6th largest, the 3d to the 6th in 

 contact with the suborbitals : two large temporal shields above the 

 three posterior labials. Centre of the eye anterior to the middle of 

 the chord connecting the apex of rostral and posterior end of labials 

 and over the middle of the 5th labial. Outline of upper jaw convex. 

 Lower labials eleven. 



Body stout and short. Tail very short, and rapidly tapering, 

 rather thicker than the thinnest part of the body. Dorsal rows 25. 

 Scales all distinctly carinated, (including those on the back of the 

 head,) except the outer row, which is either perfectly smooth, or pre- 

 sents very obsolete carination. The ridges on the 2d row much less 

 distinct than the rest. 



Color reddish brown above, with dark blotches. A series of 28 

 quadrate, dorsal, uniform black blotches from head to anus, each 

 from 2 to 3 scales long, and 7 to 9 wide, separated by regular brown- 

 ish yellow intervals of 1 J to 2 scales. The blotches anteriorly are 

 nearly square, posteriorly they are transversely elongated. Opposite 

 the intervals, and, indeed, bounding them on either side, is a second 

 series of small circular blotches on the 4th to the 8th lateral rows, 

 and separated only by a narrow interval from the corner of the dor- 

 sal blotches. Sometimes there are faint traces of small blotches be- 

 tween the upper lateral series. Intervals between the lateral rows 

 of blotches yellowish or reddish brown, darker than those on the 

 back; outer dorsal rows greenish or yellowish white. On the tail 

 there are 15 black half-rings, interrupted on the subcaudal scutellai, 



