COLUBRID^. — ex. 189 



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



lx*&i^i^ ^^ ^^ ^^' ^- ^'- lis to 125). . . . ViKGIMA, 271. 



cc. EseiSaiSrsmgre; uo preocular; uasal single; (scales 19; V.P. 170 to 



^"^^ Farancia, 272. 



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



(CoroneUmcB,^ Colubrince, Homaloj)siiUB). 

 /. 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 21). . Kegina, 277. 

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



Natrix 2TS 

 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. 



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



.. ^ , , . , Stoeeria, 274. 



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

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



.. T^T , . , . Haldea, 273. 



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



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



I'l^) Clonophis, 275. 



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

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



Mr> 1 1 X T 1 J Opheodrys, 280. 



. Dorsal scales not keeled. 



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

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

 00. 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; bead 

 rather long. 



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

 tive characters in the key. Professor Copn gives tlie following definitions • — 



Homalopsinm. (Genera 273 to 278.) " Hypaj.ophyses spinous to caudal region- an- 

 tenor teeth not enlarged; body not slenrlor; liead distinct." 



CoUbruur. (Genera 279 to 2.S3.) Head more distinct and elongate; body and tail 

 longer; teeth entire, not longer in front. 



Coronellinw. (Genera 284 to 2SS.) Head slightly distinct, short; teeth entire, 

 not enlarged in front. 



