Variation. Largest male 777 mm TL with a 135 mm tail; largest female 886 mm TL with a 124 mm tail. Head is elongated, distinct from the neck and depressed; eyes are dorsal and slightly protruding. Many of the smaller head scales anterior to the angle of the jaw have keels. Rostral as tall as broad and pentagonal; nasal may be divided, undivided or semi divided; the nasal cleft may touch labial, internasal, or loreal; internasal divided (rarely single or semi-divided); and usually in broad contact with loreal posterior to the nasals. Frontal fragmented with one or two large anterior fragments and smaller posterior fragments; in most specimens largest remaining fragment shorter than supraocular; parietals fragmented into numerous small scales. Loreal may be single or double, contacts upper labials 1 – 3 or 1 – 4 (rarely 2 – 3 or 2 – 4). Supraocular single (rarely double); preocular single or double, usually one; subocular scales 1 – 3 (usually two), but may be completely absent with 5 th or 6 th upper labial entering the orbit. Upper labials 8 – 10, usually 9, largest upper labial usually 6 (88 % of 96 sides); the last two upper labials horizontally divided. Primary temporal scales may number 1 – 3, usually two. Lower labials 8 – 11, usually 9; first four contact anterior chin shields; largest is usually 7, but it can be 6 or 8; chin shields 2 or 3 pairs, anterior pair largest. Gular scales 5 – 8, usually 6 – 7. Dorsal scale rows on anterior body 23 – 27; midbody scale rows 21 – 25, usually 23 or 25; posterior rows 16 – 20, usually 19. Specimens from India and Sri Lanka tend to have 23 midbody dorsal rows, while specimens from Myanmar tend to have 25 rows. Dorsal scales keeled and striated, except first row that shows no trace of keels; scales in first row are larger and more ovate than the rows toward the vertebral line. Ventrals rounded and wide; in males I 35 — I 52 (n = 3 O, x = I 44 • 8), females I 35 — I 52 (n = 2 I, x = I 42 • 8) • Anal plate điviđeđ • Subcauđals in males 56 — 67 (n = 2 I, x = 62 • 5), anđ 48 — 59 (n = I 9, x = 53 • 7) in females • Τail length ̸ SvL in males 2 I — 29 % (n = 2 O, x = 25 • 5 %) ﹔ females I 7 — 25 % (n = I 9, x = 2 I • 6 %) • In alcohol, dorsal surface of head uniform brown or gray with light upper and lower labials and a darker postocular stripe; dorsum gray or brown with a series of dark cross bands that extend onto the tail; belly yellow or cream, sometimes extending onto the first 2 – 3 dorsal rows; belly may be uniform or more often has a series of blotches or is mottled.
