BATRACHIAN.S AND /lEPTILES, CENTRAL AMERICA AND MEXICO. 55 



SCYTALINJi. 



ex. Anterior Icotli cl()iiy;iU\ 



Scales smooth ; rostral platcf obtuse, Macroprotodon Guicb. 



aa. Anterior teeth slifirt. 



fi. R<ijitral phito not protuberant. 

 y. Two rows of subcau«hil scutella. 

 5. Anal plate entire. 



£. Vertcbne with expanded neural spines. 



Prefrontals united ; a loreal ; s('ales smooth Gerrhosfeus Cope. 



IE. Vertebrae with narrow compressed neural spines. 

 Scale-pits double ; pupil erect; rostral plate normal; two prefrontals, 



Oxyrrhopus'^ Wagl. 



Rostral plate normal ; one nasal plate ; two prefrontals Tomodon D. & B. 



Rostral plate separating interuasals; scale pores single; two prefrontals, 



Trmerorhinus- Smith. 

 dd. Anal plate double, 

 £. Scales smooth. 

 No scale-pits ; tail short ; rostral obtuse ; nasals two ; pupil round, 



Eryfhrolamprus^ Bole. 

 One scale-pit; loreal not in orbit ; rostral obtuse ; nasals two; pupil round, 



Tacliymevis Wiegera. 



Loreal entering orbit ; pupil erect; restral obtuse ; nasals two Tarhophia^ P^leisch. 



One nasal jdate ; no scale-pits ; rostral truncate ; pn]iil erect Manolcjns^ Cope. 



EE. Scales keeled. 



Pupil erect; anal double Drijophilax Wagl. 



yy. One row of snbcaudal scuta. 



Two preoculars ; head distinct ; body compressed Biiiipophin Gthr. 



Two preoculars ; body round ; head not distinct Uologerrhum Giiuth. 



One preocular ; body round Sojtah^' Boie. 



/3/3. Rostral plate protuberant. 

 y. Rostral not recurved. 

 Loreal not entering orbit ; pupil round; two nasal plates ; rostral moderate, 



Conoj^his Pet. 



Scales not grooved ; rostral very prominent Rhaviphiophis Pet. 



Scales grooved ; rostral prominent Ehagcrhis Pet. 



yy. Rostral plate recurved. 



One row of snbcaudal scuta Plnmophh' Cope. 



Two rows of snbcaudal scutella Ixhuiostonia Wagl. 



NATRICINyE. 



A. Posterior maxillary teeth not abruptly longer than those that precede them. 



1. Rostral plate expanded transversely and with free lateral borders. 



Several preoculars ; scales smooth ; anal and subcaudals double . . . Salvadora^ B. & G. 



2. Rostral plate not expanded and free laterally. 



* Two median dorsal rows of scales. 



One preocular plate Herpelodriiasf Boie. 



Two preocular plates Zaxicys Cope. 



"* One median dorsal row of scales, 

 t Body little or not compressed. 



t Interuasals not confluent with nasals. 

 a. Several loreal plates. 



' Incliitles Jirachijrhytum I). &. B. " Olisthenes Cope. 



^Psamriiophi/lax (Fitz) Giintlior. '' lihinunimusD. & V,. proocciipi.'d 



^ Coniophanes Hiillow. "Preoccupied in botiuiy, liciirti Phiiii othyra Coxte>. 



«GuutUMsays(Catal.r>nt. Mus.,p. 33)"aniillurul." "^ Phyllosira Co\w.. 



•Type Tomodon nasutus Cope. 



