CROCODILIANS, LIZARDS, AND SNAKES. 



989 



NATRIX RIGIDA Say. 



Coluber rigidus Say, .Tourn. Acart. Nat. Sci. Phila., 1825, IV, p. 239.— H.\rlan, 



.lourn. Acad. Nat Sci. Phila., V, 1827, p. 355. 

 Tropidonotits rigidus Ht)LnR(>OK, N. Amer. Herp., 1842, III, p. 39, pi. X. — C'oi'E, 



Check-list N. Aincr. Batr. Kept., 1875, p. 42. — Boulkxgeu, Cat. SuakesBrit. 



Mils., I, 1893, p. 240. 



Greenish brown above; two deep brown vittu' along the dorsal 

 region. Contignoas edges of the outer row of scales and abdominal 

 seutelhe finely margined with brown. The middle region of the outer 

 row like the abdomen, as is that of the secoud row, but less distinctly. 

 Abdomen reddish yellow, with two series of black spots on the middle 

 region, approaching each other toward the anterior region of the body. 

 Dorsal rows of scales nineteen, 

 carinated excei)t the outer row, 

 which is smooth. 



Head proportionately larger than 

 In R. lebcris, much less depressed 

 and shorter on the snout. Its 

 upper surface is flat, the snout 

 convex, the high and large ros- 

 tral making it less sloping. Front 

 plate subhexagonal and elongated. 

 Parietals truncated posteriorly. 

 Superciliaries narrow and taper- 

 ing forward. Anterior pair of 

 frontals very small. Two post- 

 orbitals of nearly equal size, and 

 two anteorbitals, the upper one 



much larger than the lower. Loreal subcircular or oblong. An elon- 

 gated and narrow tenii»oral shield, followed by two or three smaller. 

 Upper labials seven, fifth and sixth very large. Lower labials eleven, 

 sixth and seventh largest. Scales elliptical, narrower along the middle 

 line of the back, carinated, except the outer row. which is perfectly 

 smooth, an(l furthermore distinguished by the scales having their height 

 greater than their length. The second row is noticeable for its size, and 

 sometimes for its want of carination, which in all cases is obsolete. 



The groundcolor is unifoim greenish brown, but each scale on the 

 flanks is marked with a small blotch of deeper brown at its base. The 

 brown vittse of the back cover each one entire row and the half of 

 the two adjoining rows, separated on the dorsal line by one row and 

 two half-scales of the ground-color. Beneath dull yellowish. Along 

 the middle region of the abdomen there are two series of elongated 

 deep brown blotches approaching each other toward the anterior 

 region and under the tail, sometimes, however, not extending beyond 

 the anus. 



This species approaches near to the N. (jnihamii, but ditters in the 



Pig. 262. 

 Natrix rigiua Say. 

 = 1. 

 Georgetown, South Carolina. 



Cat. Nn. 13S7, U.S.N.M. 



