Description. _Body_ black, _anterior half_ with a series of continuous, dilated dull-red large circles, formed upon the skin between the scales, on the side; on many of the scales, are white marginal dashes near their bases: these scales are placed in groups each side of the vertebræ of the anterior moiety of the body; _scales_ bipunctured at tip; _beneath_ flat, so as to produce an angle or carnia each side; white slightly tinged with yellowish red, irrorate with black points, and spotted with large oblong quadrate marks, which gradually become more continuous, confluent and plumbeous towards the tail, occupying nearly the whole surface; _head_ beneath and _throat_ pure white; posterior _canthus_ of the eye two-scaled; _iris_ blackish; _pupil_ deep-blued black, enclosed by a silvery line. One specimen, Pl. 228 -- Sc. 67 ? Another specimen Pl. 233 -- Sc. 84 Another specimen Pl. 228 -- Sc. 84 Total length -- 4 feet 11-5/8 inches. Tail length 4 feet 10-1/8 inches. The lateral red marks are not perceptible, unless the skin be dilated so as to separate the scales; and the small white marginal lines on the bases of some of the scales are observable only on close inspection. It varies in being nearly or quite destitute of spots on the anterior portion of the body beneath, but the posterior half of the inferior surface still remains blackish. The whole animal bears strong resemblance to C. _constrictor_; but the scales are decidedly smaller, and the number of its plates and scales approach it still more closely to that uncertain species C. _ovivorus_. It is not an uncommon species on the Missouri from the vicinity of Isle au Vache to Council Bluff. _Penis_ terminated by a hemisphere, covered with compressed, white spines, which are reflected at tip; the series interrupted on the posterior side of the member by a canal; _it_ is much dilated, dark reddish brown, abruptly contracted at base from the exterior side, and with a prominent tubercle on the middle of the inner side: length one inch and a quarter, width about seven-sixteenths of an inch.--JAMES. [164] The Grand Nemahaw, now usually called Big Nemaha, does not rise so far to the west as is here implied. Its sources are in Lancaster County, Nebraska, almost directly north of the mouth of Republican River. The confluence of the Big Nemaha is just above the Kansas-Nebraska line. There are two streams (Big and Little) called Tarkio Creek. They flow parallel through Atchison and Holt counties, Missouri. The mouth of the Big Tarkio is opposite that of the Big Nemaha; that of the Little Tarkio is now about eleven miles below, but the channel is very changeable. Tarkio is said to mean "full of walnuts."--ED. [165] The Little Nemaha flows through the Nebraska county of the same name; its mouth is between the towns of Aspinwall and Nemaha.--ED.