AMPHIBIANS AND REPTILES. 145 
ff. Loreal plate wanting; ventral plates 125 to 130; scales 
transversely I5 to I7. STORERIA 
ee. Nasal plate single, pierced by nostril; loreal plate present 
1. Nasal plate grooved; tail short; ventral plates 
130 to 140; scales transversely 19. CLONOPHIS 
ui. Nasal plate not grooved below nostril; tail 
very long, about 4% of length; ventral plates 
150 to 160; scales transversely 17. OPHEODRYS 
dd. Dorsal scales not keeled. 
j. Nasal plate single, pierced by nostril; loreal 
plate present; tail long; ventral plates 125 
to 140; scales transversely 15. LIOPELTIS 
jj. Nasal plates 2, with nostril between; loreal 
plate present; preocular plates 2. 
k. Head depressed; preocular plates of 
nearly equal size; ventral plates 140 to 
200 or more; scales transversely 15 to 17. 
DIADOPHIS 
kk. Head not depressed; upper preocular 
plates much the larger, lower sometimes 
wanting; ventral plates I70 to 210; 
scales transversely 17. BASCANION 
cc. Anal plate entire. 
1. Dorsal scales all or partly keeled; 
head rather long. 
m. Prefrontals 2 pairs, or 4 or 
more; ventral plates 200 to 250; 
scales transversely 25 to 35. 
PITUOPHIS 
mm. Prefrontals I pair; ventral plates 
140 to I80; scales transversely 
19 to 21. THAMNOPHIS 
ll. Dorsal scales not keeled, rather 
loosely imbricated; head short; ven- 
tral plates 160 to 240. §LAMPROPELTIS 
bb. Rostral plate produced, recurved and keeled; dorsal scales keeled; 
anal plate divided; head broad and short; some of posterior teeth 
enlarged; ventral plates 120 to 150; scales transversely 23 to 27. 
HETERODON 
I0 MU 
