COLUBRID^E. CX. 189 



dd. Nasal plates 2, the nostril between them; a loral plate; no preocu- 



lar; (scales 15 or 17, V. P. 115 to 125). . . . VIRGINIA, 271. 



cc. Prefrontal single ; no pveocular; nasal single; (scales 19; V. P. 170 to 



205) FARANCIA, 272. 



aa. Head more or less distinct from the body which is not specially rigid 



(Corontllince, 1 Colubrince, Homalopsince). 

 f. Rostral plate normal, not recurved nor keeled. 

 g. Anal plate divided ; head not very short. 

 h. Dorsal scales keeled more or less. 

 i. Nasal plates 2, the nostril between them. 

 j. Prefrontals 2. 



k. Loral plate present. 



/. Scales on back and sides all keeled (ventral plates 130 to 170). 

 m. Posterior teeth not longer (scales 19 to 2i). . REGINA, 277. 

 mm. Posterior teeth longer (scales 23 to 31). 



NATRIX, 278. 



II. Scales on sides not keeled; those on back often with the 

 keels obscure (V. P. 200 to 270; scales 25 to 29). 



CALLOPELTIS, 279. 

 lelc. Loral plate absent (scales 15 to 17; V. P. 125 to 130). 



STOHERIA, 274. 



jj. Prefrontal single ; nasals 2 : loral present ; no preocular (scales 17 ; 

 V. P. 120 to 130) ; body slender, the head distinct. 



HALDEA, 273. 

 **. Nasal single, pierced by the nostril; loral plate present. 



n. Nasal plate grooved; tail short (scales 19; V. P. 130 to 



140) CLONOPHIS, 275. 



nn. Nasal plate not grooved below nostril ; tail very long, 

 about * of length (scales 17; V. P. 150 to 160). 



OPHEODRYS, 280. 

 Ah. Dorsal scales not keeled . 



o. Nasal single, pierced by the nostril; loral present; tail 

 long (scales 15 ; V. P. 125 to 140). LIOPELTIS, 281. 

 oo. Nasal plates 2, the nostril between them; loral pres- 

 ent ; preoculars 2. 



p. Head depressed; preoculars nearly equal in size 

 (scales 15 to 17; V. P. 140 to 200 or more). 



DIADOPHIS, 284. 



pp. Head not depressed; upper preocular much the 

 larger; lower sometimes wanting; (scales 17; V. 



P. 170 to 210) BASCANION, 282. 



gg. Anal plate entire. 



q. Dorsal scales all or part of them keeled; head 

 rather long. 



1 These three sub-families are so vaguely bounded that I cannot use their distinc- 

 tive characters in the key. Professor Cope gives the following definitions : 



Homalopsince. (Genera 273 to 278.) " Hypapophyses spinous to caudal region; an- 

 terior teeth not enlarged; body not slender; head distinct." 



ColubrincK. (Genera 279 to 283.) Head more distinct and elongate; body and tail 

 longer; teeth entire, not longer in front. 



Coronellince. (Genera 284 to 288.) Head slightly distinct, short ; teeth entire, 

 not enlarged in front. 



