SNAKES. 7 



but without sharp ridge) ; upper jaw much longer than lower ; 

 mouth moderately cleft ; only one pair of frontals, large, six- 

 sided, bent on the sides ; vertical very large, longer than broad, 

 six-sided, with an obtuse angle in front, and an acute one behind ; 

 superciliaries elongate ; occipitals rather large, rounded behind ; 

 one nasal, pierced by a very small nostril, in direct contact with 

 the ante-ocular ; one anterior ocular, not raised on the surface 

 of crown ; two posterior oculars ; loreal none ; seven upper 

 labials, third and fourth forming the lower edge of orbit ; one 

 large elongate temporal, in contact with both hinder oculars, 

 some scale-like shields behind ; first pair of lower labials form- 

 ing a suture behind the terminal shield ; two pairs of chin-shields, 

 the anterior one largest, each half irregularly five-sided, twice as 

 long as broad. Scales smooth, rather short, rounded at the tip, 

 in seventeen rows; ventral plates 118, anal bifid, subcaudals 38. 

 Nearly \miform dark olive ; on the anterior part of back some 

 obsolete black spots ; sides lighter ; belly yellowish white ; edges 

 of each ventral plate with two or three black spots. Length of 

 cleft of mouth I" ; length of tail 2" ; total length 10". 



3. i^MBLYMETOPON, GuTither. 



Body rounded, moderate ; tail short ; head short, convex, not 

 distinct from neck ; neck not distensible ; rostral shield promi- 

 nent, recurved, sharp above, forming a broad suture with the 

 vertical ; one pair of frontals, separated by the vertical ; nostril 

 between nasal and first upper labial ; scales smooth, short, in 

 seventeen rows, square ; subcaudals two-rowed. Teeth in both 

 jaws equal, smooth ; palatine teeth. Mexico. 



1. Amblymetopon variegatum. 



Whitish, with black cross bars; belly uniform whitish. 



a. Mexico. From M. Salle's Collection. 



b. Mexico. Adult female in a bad state. 



Description of the specimens. — Body moderate ; tail rather 

 short, tapering ; head not distinct, convex, with rounded crown ; 

 muzzle not elongate ; cleft of mouth rather short ; eye mode- 

 rate, pupil subelliptical. Rostral shield very peculiarly shaped : 

 bent upwards, with a sharp, convex ridge above, as in Rhino- 

 stoma, but much narrower, provided with a long posterior pro- 

 cess, not tapering behind, forming a broad suture with the 

 vertical, so as to separate entirely the frontals ; only one pair of 

 frontals, each quadrangular, large, spheroidal; vertical large. 



