OP HID I A. 



one-third broader than deep. The mouth is deeply cleft, concave 

 downwards, a little behind the orbit. The snout is slightly pro- 

 truding beyond the lower jaw. The eye is large and subelliptical, 

 its horizontal diameter being somewhat more than half the distance 

 between its anterior rim and the extremity of the snout. The 

 cephalic plates are all conspicuously developed, the occipitals being 

 the largest of the set, and nearly as wide anteriorly as the vertex plate 

 is long ; the latter is subpyramidal, with its rounded summit directed 

 backwards, whilst its sides are slightly concave upon their middle. 

 The supraocularies are a little longer than the vertex plate, obtusely 

 subtriangular in shape, broadest posteriorly, where they meet the 

 occipitals. The postfrontals are larger than the prefrontals, subquad- 

 rangular when viewed from above, and extending to the sides of the 

 head, as far as the loral, between the postnasal and the anteorbital. 

 The prefrontals are exteriorly rounded, narrowest in front. The 

 rostral is broad and low, and scarcely seen in an upper view of the 

 head. There are two nasals, with the nostril between, encroaching, 

 however, more upon the postnasal than the prenasal, which appears a 

 little larger. The loral is elongated and narrow, rounded upon its 

 upper edge. The anteorbital, narrow upon its base, widens as it 

 ascends, thrusting itself between the supraoculary and the postfrontal, 

 and appearing upon the upper surface of the head. There are two 

 postorbitals, the inferior one being the smallest. An elongated 

 temporal shield may be seen between the postorbitals, posterior upper 

 labials, and the occipital plate, followed by two others more scale-like 

 in their appearance. The upper labials, eight in number, are in- 

 creasing in size posteriorly ; the fourth and fifth constitute the 

 inferior rim of the orbit, the anteorbital resting upon the fourth, and 

 the inferior postorbital upon the fifth. On the right side of our 

 specimen the seventh and eighth upper labials are united into one 

 plate. The symphyseal is rather small and triangular. There are 

 nine, mayhap ten, inferior labial plates ; the first one is vertically 

 elongated, and meets its fellow so as to inclose the symphyseal, thus 

 separating it from the anterior pair of mental shields ; the second is 

 the smallest; they increase in size to the sixth, which is broadly 

 developed and the largest of all, hence they diminish posteriorly. 

 The posterior mental shields are very long and slender, longer and 

 narrower than the anterior pair. The sides of the throat are covered 

 with elongated scale-like shields. 



