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 2 1 rows. 



Heterodon. p. 654. 



cccc*. Pupil vertical; rostral with free edges; scales in 



19 rows. 



Phyllorhynchus. p. 692. 



Genus 26. Diadophis 



DiaJofAii BAIRD & GIRARD, Cat. N. Amer. Rept., Pt. I, Serpents, 1853, 

 p. 112 (type, functatus); 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 1 5 or 1 7 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. 



