SYNOPSES AND DESCRIPTIONS. 



4S 



fifth labials, pupil round. Snout prominent, produced, rounded. Mouth- 

 cleft deep, curving. Teeth equal, smooth. Sides of the head concave 

 in front of the eyes. Crown-shields nine, lai'ge, elongate. Rostral con- 

 vex, little bent back between the internasals. Prefrontals large, slightly 

 decurved upon the side. Frontal long, l)road in front, becoming narrow 

 at the middle, sides parallel posteriorly. Supraciliaries large, convex, 

 prominent over the eye. Parietals broad. Nasal in two parts, nostril 

 Ixetween. Loreal higher than long. Two preoculars ; upper large, pro- 

 jecting over the loreal, upper angle in contact Avith the frontal; lower 

 small in a notch between the third and fourth labials. Postoculars two, 

 lower resting on the fifth labial. Two or three temporals in contact with 

 the orbitals. Labials eight, posterior two largest. Infralabials ten, fifth 

 largest. Submentals two pairs, subequal. Scales smooth, in 17 rows, 

 outer broader. Ventrals 200—206 (with varieties 190—206). Anal bifid. 

 Subcaudals 94 to 111 pairs. Frequently there is a short incision in the 

 upper preocular near the ujiper edge of the loreal, sometimes this is met 

 by another, cutting out a triangular piece of the shield. 



Young whitish, uniform posteriorly, with narrow transverse bands of 

 brownish anteriorly. The bands darken toward the head, which is banded 

 and clouded with brown, darkest on the supraciliaries. 



Adult dark anteriorly — brown to black, mixed white and brown medially, 

 and whitish posteriorly. Belly dark anteriorly, clouded with brown, tinged 

 with red in the middle and white posteriorly. Upper anteorbital with a 

 yellow spot next the eye. The species varies considerably in the depth 

 of the color of the anterior half of the body and in the amount of yellow 

 about the chin. Mississippi river and eastward. 



var. TESTACEtrs. 



C^OLUBEK TESTACEUS. Say, 1823, Lmtfs Fxp. II, 48. 



Elongate, tapering to head and tail; head a little larger than the neck, 

 long, quadrangular in transverse section at the eyes, Avith concave sides, 

 arched from the snout liackward; tail near one fourth of the total, tapei'ing. 

 slender. Eye large, pupil round, brows overhanging. A couple of the 

 posterior maxillary teeth a little longer. Crown-shields normal. Pre- 

 frontals broad anteriorly, bent downward at the sides. Frontal broad in 

 front, narrow in the posterior half. Supraciliaries broadening backward. 

 Nasal divided. Loreal small, lozenge-shaped. Preoculars two; lower 



