Tropidonotus viperinus.
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.
α. A subocular below the preocular.
* Scales smooth, in 17 or 19 rows.
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
Zamenis gemonensis.
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
Zamenis dahlii.
** Scales in 23 to 29 rows (usually 25 or 27), with two apical pits.