Cope.] 48o [ Ma y 21, 



Rostral plate produced both anteriorly and posteriorly. .Holarchus* Cope. 



No scale-pits ; rostral plate not produced , Megablabes Gtlir. 



Two scale-pits Ophibolus\ B. & G. 



aa. Dentition diacranterian. 

 8. Rostral plate normal. 



y. Anal plate entire. 



Eye bounded by scales below ; lores plane Cydagras\ Cope. 



Eye resting on labial plates ; lores plane Xenodon^ Boie. 



Eye on labials ; lores grooved ; two scale- pits Teleolepis Cope. 



yy. Analplatedivided.|| 

 3. Scale-pits present (one). 



Head very distinct ; robust Xenodon Boie. 



Head little distinct ; slender Liophis Wagl. 



83. No scale- pits. 

 e. Rostral plate normal. 



Tail short ; pupil erect ; lores flat Hypsiglena^ Cope. 



Tail short ; pupil round ; body robust Opheomorphus Cope. 



Tail short ; pupil round ; body slender Aporophis Cope. 



Tail very long ; pupil round ; slender Dromicus Bibr. 



£s. Rostral plate produced backwards and laterally, not 

 forwards. 



Anal divided ; loreal present .' Lytorhynchus** Pet. 



/5,3. Rostral trihedral and produced. 



Anal divided ; scales keeled Eeterodon Beauv. 



Anal divided ; scales smooth LystropMs\-\ Cope. 



Anal entire ; scales smooth Lioheterodon Dum. 



SCYTALINiE. 



a. Anterior teeth elongate. 



Scales smooth ; rostral plate obtuse Macroprotodon Guich. 



aa. Anterior teeth short. 

 3. Rostral plate not protuberant. 



y. Two rows of subcaudal scutella. 

 8. Anal plate entire. 

 e. Vertebras with expanded neural spines. 

 Prefontals united ; a loreal ; scales smooth Gerrhosteus Cope. 



*Uen. nov., embracing all species with entire anal plate hitherto referred to 

 Simotes. 



t Lamp rope Ids Fitz., Cope, Bellophis Lockingt. 



% Lejosopliis Jan. 



i Xenodon suspectus Cope; X. colubrimi.s Gthr. ; A'. angustiroBtris Pet.; and A". 

 blprceoculcwis Cope ; and double or single in A', rhabdocephalus VVied. 



|| Pseudoxyrrhopus Gtlnlhr. (.* ' Hmnnlocephahix Jan.) is probably identical with 

 one of the genera of sect, yy, but the character of the scale-pits Is unknown. 



% Pseudod i psas Pet. Comasles Jan. 



** Catachlein Jan, Ophirhina Bocage. 



tt'fype llelerodon dorbignyi. 



