16. 
Tl 
bts} 
19. 
Z0%e 
le 
22. 
DE 
24. 
25. 
20% 
DT fer 
28.6 
29. 
30. 
Se 
Back mostly green, with a few crossbars Opheodrys 
Back partly green 17 
Upper labials 7, third and fourth bordering eye; 15 scale 
rows throughout Liopeltis 
(A single species: L. frenatus) 
Upper labials less than 6 18 
Nape of neck with arrow-shaped mark; 15 scale rows... 
Plagiopholis 
No such mark on neck; 13 or 15 scale rows; nape with groove 
Trachischium 
Seventeen scale rows throughout; back brown, with a black 
mark on top of head Sibynophis 
More rows of scales on neck than at midbody, or fewer than 
17 at end of body 20 
Ventrals with a keel and notch laterally; body and _ tail 
slender Chrysopelea 
(A single species: C. ornata) 
Belly without keel or weakly keeled; in either case ventrals 
without a notch 2 
Dorsal scale rows oblique, at least anteriorly... 
Pseudoxenodon 
Scale rows not oblique 22 
Back with crossbars 23 
Back without crossbars 24 
Posterior group of maxillary teeth 3 Dinodon 
Posterior group of maxillary teeth 2 Lycodon 
Back with lines Psammophis 
(A single species: P. lineolatus) 
Back not lined Psammodynastes 
(A single species: P. pulverulentus) 
Three or more postoculars 2g 
At most 2 postoculars 26 
Back with reddish crossbars, 28-35+9-13 Dinodon (part) 
Without above pattern Elaphe 
Loreal variable (0-2); eye small; some subcaudals_ not 
paired; subcaudals more than 200 Thermophis 
(A single species: T. baileyi) 
Loreal single, rarely 2; all subcaudals paired, less than 
200 28 
Hemipenis forked, sulcus spermaticus divided or not 29 
Hemipenis and sulcus spermaticus simple 31 
Sulcus spermaticus divided 30 
Sulcus spermaticus simple Sinonatrix 
Maxillary dentition continuous, teeth gradually or abruptly 
larger posteriorly Xenochrophis 
(A single species: X. piscator) 
Maxillary dentition with posterior two teeth stroangly 
enlarged, recurved, preceded by a diastema Rhabdophis 
Maxillary dentition continuous, teeth gradually larger 
posteriorly in the series; internasals narrowed anteriorly, 
nostrils dorsolateral Natrix 
Maxillary dentition usually coantinuous, teeth gradually 
becoming larger posteriorly or the posterior two abruptly 
enlarged, occasionally separated from the preceding teeth; 
internasals broad anteriorly, nostrils lateral 32 
