Key to Families of Snakes 
Small snakes, worm-like; all scales around body same size; 
eye obscured under scales Typhlopidae 
Moderate or large snakes; ventral scales usually larger than 
dorsals; eye not obscured 2 
Tail compressed 3} 
Tail cylindrical 4 
Granular scales on body; top of head without’ enlarged 
scales Acrochordidae 
(A single species: Acrochordus granulatus) 
Scales of body not granular; top of head with large, 
Symmetrical scales Hydrophiidae 
Width of ventral scales less than 3 times width of adjacent 
lateral scales 5 
Width of ventrals more than 3 times width of adjacent scales 
6 
More than 30 rows’ of dorsal scales; vestige of hind limb 
present Boidae 
Scale rows 15; no vestige of hind limb Xenopeltidae 
No grooved or tubular fangs at front of upper jaw... 
Colubridae 
Fangs present at front of upper jaw 7 
Immovable, grooved fangs; pupil usually round; body slender; 
usually black or dark brown on back, black alternating with 
white or brown, or with longitudinal stripes Elapidae 
Tubular, movable fangs; pupil vertical or oval; _ head 
triangular; neck slender; a pit on side of head present 
(Crotalinae) or absent (Viperinae) Viperidae 
TYPHLOPIDAE 
Key to species 
Scales in 20 rows; nasal divided into two parts 
Ramphotyphlops braminus 
Scales in 22-23 rows; nasal divided only from nostril to 
contact with second labial Typhlops koshunensis 
Scales in 24-28 rows, rarely 22; nasal divided only from 
nostril to contact with second labial Typhlops diardi 
BOIDAE 
Key to species 
Head distinct from neck, with large symmetrical shields; 
rostral and first two supralabials with pits 
Python molurus 
Head not distinct from neck, small scales on _ head; = no 
supralabials with pits Eryx miliaris 
XENOPELTIDAE 
Key to species of Xenopeltis 
Eight upper labials, 3-2-3; 2 postorbitals; ventrals 164- 
196; subcaudals 22-31 unicolor 
Seven upper labials, 3-2-2; one postorbital; ventrals 152- 
164; subcaudals 16-19 hainanensis 
