2. Dorsal scales smooth or feebly keeled; normally a single loreal.
_a._ Two or three superposed anterior temporals (very rarely one); nostril usually between two nasals.
[alpha]. A subocular below the preocular.
Two upper labials entering the eye; preocular not in contact with the frontal; scales with two apical pits; ventrals more or less distinctly angulate laterally, 160-230; subcaudals 87-131
Two upper labials entering the eye; preocular usually in contact with the frontal; scales with a single apical pit; ventrals very distinctly angulate laterally, 205-218; subcaudals 98-132
** Scales in 23 to 29 rows (usually 25 or 27), with two apical pits.
Upper labials usually separated from the eye by a series of suboculars; preocular in contact with the frontal; scales smooth; ventrals very distinctly angulate laterally, 222-258; subcaudals 77-107
Two upper labials entering the eye; preocular not in contact with the frontal; scales feebly but distinctly keeled; ventrals not angulate laterally, 195-234; subcaudals 56-90
Two upper labials entering the eye; preocular not in contact with the frontal; scales smooth or faintly keeled; ventrals not or but very obtusely angulate laterally, 172-214; subcaudals 50-80
[beta]. No subocular; scales smooth, or faintly keeled on the posterior part of the body.
* Ventrals more than 200; scales with two apical pits.
Snout obtuse; rostral broader than deep; scales in 21 or 23 rows; ventrals distinctly angulate laterally, 212-248; subcaudals 60-91
Snout obtuse; rostral broader than deep; scales in 25 or 27 rows; ventrals not angulate laterally, 222-260; subcaudals 68-90
Snout pointed, strongly projecting; rostral deeper than broad, wedged in between the internasals; scales in 25 to 29 rows; ventrals not angulate laterally, 201-220; subcaudals 48-68
** Ventrals not more than 200; scales mostly with a single apical pit.
Rostral at least as deep as broad, often wedged in between the internasals; usually 7 upper labials, third and fourth entering the eye; scales in 19 (rarely 21) rows; ventrals 153-199; subcaudals 41-70
Rostral broader than deep; usually 8 upper labials, fourth and fifth entering the eye; scales in 21 (rarely 19 or 23) rows; ventrals 170-200; subcaudals 49-72