130 ♦ OP HID I A. 



snout protrudes slightly beyond the lower jaw. The cleft of the 

 mouth is descending from the tip of the lower jaw to a vertical line 

 drawn behind the eye, hence ascending to its angle. The eye is large 

 and circular; the pupil is circular also. The nostril occupies the 

 upper portion, between two nasal plates, its superior rim being 

 formed by the prefrontal plate. The occipital plates are more 

 develoj)ed than any of the cephalic series; they are broadest ante- 

 riorly, diminishing in width posteriorly, rounded upon the latter 

 margin, and nearly rectilinear laterally. The vertex plate is very 

 broad anteriorly, tapering posteriorly, where it is rounded ; the sides 

 are somewhat concave. The supraocularies are obtusely triangular. 

 The frontals are subquadrangular, the postfrontals being but a little 

 larger than the prefrontals, if we except that portion which extends 

 towards the loral region. The rostral is well developed, broad, and 

 low. The postnasal is larger than the prenasal, both being con- 

 tiguous inferiorly. The loral is narrow and elongated. The ante- 

 orbital is narrow inferiorly ; ii expands upwards, and appears on the 

 upper surface of the head, under the shape of a small triangle. There 

 are two postorbitals, the inferior one being much smaller than the 

 upper. Four temporal shields of considerable development may be 

 observed. There are eight upper labials ; the anterior three are the 

 smallest ; the fourth and fifth constitute the inferior portion of the 

 orbit, and are, together with the sixth and seventh, the largest ; the 

 ninth is smaller than the preceding. There are ten inferior labials ; 

 the sy mphyseal is small, triangular, and inclosed by the first pair of 

 inferior labial plates, which are narrow and elongated ; the fifth and 

 sixth are the largest of the series ; the posterior four diminish 

 gradually towards the angle of the mouth, whilst the anterior four 

 increase in size from the symphyseal backwards. The mental shields 

 are well developed ; the posterior pair is narrower and more elongated 

 than the anterior pair. Scale-like shields may be observed on the 

 sides of the throat. 



The body is very elongated and very slender, deeper than broad 

 throughout its whole extent, and most developed upon the middle 

 region. The belly is nearly flat, and laterally keeled, a result of the 

 bent of the scutellae. The tail, which forms about the third of the 

 entire length, is very slender and tapering to a point ; it is likewise 

 deeper than broad throughout its entire length; its inferior surface is 

 flattened, keeled on each side like the belly, owing to the flexions 



