186 " * OP HID I A. 



somewhat spear-shaped, with the base towards the eye, and contiguous 

 anteriorly to the postfrontal, second and third upper labials. An infe- 

 rior orbital, subcrescentic in shape and concave upwards, constitutes 

 the inferior rim of the orbit. It is contiguous above to the ante- 

 orbital, in front with the third labial, beneath with the fourth and fifth 

 labials, and posteriorly with the lower postorbital and a temporal 

 shield. Two postorbitals, nearly equal sized, complete the orbit pos- 

 teriorly; sometimes, three postorbitals maybe observed, in which case, 

 the third is a mere subdivision of the inferior orbital. Both the tem- 

 poral and occipital regions are covered with comparatively large, poly- 

 gonal, scale-like shields or plates. The upper labials are eight in num- 

 ber ; the second is conspicuously the largest, and the first nearly equal 

 to the third ; the fourth, fifth, and sixth, are smaller still ; the seventh 

 and eighth, the smallest of the series, occupy the upper and oblique 

 branch of the gape of the mouth. The lower labials may be num- 

 bered twelve ; the posterior four are scale-like, occupying the oblique 

 ascending branch of the gape of the mouth ; the sixth, seventh, and 

 eighth, are quite inconspicuous and small ; the first, fourth, and fifth, 

 are the largest; the second and third being somewhat smaller. The 

 labials of the first pair are contiguous posteriorly, inclosing a very 

 small symphyseal. There is only one pair of well-developed, irregu- 

 larly rounded, mental shields ; the remaining portion of the inferior 

 surface of the head being covered with elongated scales, somewhat 

 larger than the scales of the body. 



The body is stoutest upon its middle region ; it is compressed, rather 

 rounded upon the anterior third of the dorsal region, w^hilst it is thin- 

 ning off posteriorly and beneath, so as to present a rather conspicuous 

 dorsal ridge, and a sharp belly. The scales, which extend to the abdo- 

 men, as well as to the back and sides, and thus suppressing entirely 

 the abdominal scutellae, — are very uniform in size, small, subhexago- 

 nal, and smooth, mayhap a little larger above and beneath than on 

 the middle of the sides. They constitute longitudinal series : sixty- 

 two in number across the line of greatest depth of the body, and fifty- 

 four around the neck. Four pairs of small plates may be observed 

 about the preanal region. The tail is small, forming the eighth or 

 ninth of the entire length, very much compressed, very thin and ob- 

 tuse posteriorly. The scales upon the latter region are larger than on 

 the body, but do not constitute longitudinal series. 



The upper surface of head, and the dorsal region to the middle of 



