26. DIADOPHIS 647 
dddd.—Rostral normal; scales in not more than 21 
rows. 
Natrix.—p.783. 
dddd’.—Rostral produced and turned up at tip; scales 
in more than 21 rows. 
Heterodon.—p. 654. 
ceccc.—Pupil vertical; rostral with free edges; scales in 
19 rows. 
Phyllorhynchus.—p. 692. 
Genus 26. Diadophis 
Diadophis Bairp & Girarp, Cat. N. Amer. Rept., Pt. I, Serpents, 1853, 
p. 112 (type, punctatus); Cope, Report U. S. Nat. Mus. for 1898, 
1900, p. 743. 
The body is slender, with long, tapering tail, and slight 
constriction at neck. The head is flat-topped, with broad, 
rounded snout. Its plates are normal. The nasal plates 
very rarely unite above the nostril. There are two pre- 
oculars and two postoculars. Temporals are 1+1. A loreal 
is present. The scales are smooth, in 15 or 17 rows, each 
with one apical pit. The anal plate is divided, and the 
urosteges are in two series. The eye is moderately large, 
with round pupil. 
Synopsis oF SPECIES 
a.—Scales usually in 15 rows, sometimes 17; smaller; 
gastrosteges 182 to 212. 
D. amabilis.—p. 648. 
a.—Scales in 17 rows; larger; gastrosteges 212 to 237. 
D. regalis.—p. 652. 
