III. Eyes small, moderate, or large; ventral shields at least nearly as broad as the body; tail tapering to a point; subcaudals paired.
A. Pupil round; upper surface of head with nine large shields; no upper labial in contact with the parietal; anal shield usually divided.
1. Dorsal scales strongly keeled, with paired apical pits; a single anterior temporal.
a. Nostrils lateral; internasals broadly truncate in front.
Scales in 19 rows; normally 1 pre- and 3 postoculars; usually 7 upper labials, third and fourth entering the eye; ventrals 157-181; subcaudals 50-88
Tropidonotus natrix.
b. Nostrils directed upwards; internasals much narrowed in front.
Scales in 19 rows; normally 2 pre- and 3 or 4 postoculars; suboculars sometimes present; usually 8 upper labials, fourth or fourth and fifth entering the eye; ventrals 160-187; subcaudals 48-79
Tropidonotus tessellatus.
Scales in 21 (rarely 19 or 23) rows; normally 1 or 2 pre- and 2 postoculars; usually 7 upper labials, third and fourth entering the eye; ventrals 147-164; subcaudals 46-72