646 13. COLUBRIDZ 
eee.—Rostral very large, with free lateral edges; 
coloration in spots, and blotches. 
Phyllorhynchus.—p. 692. 
eee .—Rostral normal, without free edges; colora- 
tion in blotches. 
fff.—-Gastrosteges fewer than 200. 
Hypsiglena.—p.779. 
fff'.—Gastrosteges more than 200. 
Trimorphodon.—p. 884. 
b’.—Anal plate single. 
cc.—Urosteges in one series (at least anteriorly). Snout 
protruding; coloration in cross-bands. 
Rhinocheilus.—p. 773. 
cc .—Urosteges in two series. 
ddd.—Scales in 21 to 23 rows; loreal nearly as high 
as long; rostral not protruding; coloration in 
rings, blotches, or lines. 
Lampropeltis.—p. 740. 
ddd’.—Scales in 27 to 31 rows; loreal elongate; 
rostral prominent; coloration in blotches. 
Arizona.—p. 701. 
a’.—Dorsal scales keeled. Laterals keeled or smooth; 
urosteges in two series. 
bb.—Anal plate single. 
ccc.—Prefrontals normally four (often two); scales in 
27 to 35 rows, several of the lower usually smooth; 
no longitudinal lines. 
Pituophis.—p.705. 
ccc.—Prefrontals two; scales in 17 to 23 rows; not more 
than three smooth; usually with longitudinal 
lines, sometimes spotted or unicolor. 
Thamnophis.—p. 787. 
bb’.—Anal plate divided. 
cccc.—Pupil round; rostral not free at edges. 
