The body is elongate, and strongly laterally compressed. The tail is long, as the common name implies. The dorsum is olive to light brown. There is a narrow whitish, black-edged, vertebral stripe. The upper labials and the ventrum are yellowish.
The ventrals are 178–183, and the subcaudals are 172–202. (Both these counts are higher than in C. carinatus.) The dorsal scales are arranged in 12 rows anteriorly and at midbody, in 10 rows posteriorly. (C. carinatus has 8 rows posteriorly.)
Adults may attain a total length of 136 cm (4 ft 6 in), with a tail 56 cm (22 in) long.[2]