56 BULLETIN 32, UNITED STATES NATIONAL MUSEUM. 



Two or more i)rcoculars I'fijas Cope. 



aa. One loreal (rarely two). 

 fi. Four or more jirefroiitals. 



Anal entire ; scales keeled .• Pityophis Holbr. 



/3/3. Two preCroutals only. 

 }'. Two nasal plates. 

 • d. Anal entire. 



Scales smooth ; rostral produced Bhitiechis^ Mich. 



One preocular ; rostral not produced Spilotes'^ Wagl. 



dd. Anal double. 



E. One preocular. 



Form robust; scales without pits; tail moderate Grayia^ Gthr. 



Form robust; tail moderate; two scale-pits Xairix* Laur. 



Like Coluber, but median dorsal row of scales much enlarged Xenelaphis Gthr. 



Form elongate; tail long; two scale-pits Brymohim^ Cope. 



Form very slender ; tail verj'^ long Dendrophin Boie. 



E£. Two preoculars. 



Scales keeled ElapMs Aldv. 



Scales smooth Bascaniunif' B. & G. 



7) . One nasal plate. 



Scales keeled; a loreal plate Cydoplns' Gthr. 



Scales smooth ; a loreal plate Uopeltis Cope. 



Scales smooth ; no loreal Phrafjmilophis Gthr. 



U Internasals confluent with nasals. ' 



Scales smooth with one pit ; anal divided Symphinms Cope. 



tt Body much compressed. 



One nasal plate ; a frenoorbital Dryocalamus Gthr. 



Two nasals ; a frenoorbital ; teeth equal Odontomna^ J). &.B. 



Two nasals ; loreal and i^reocular distinct Gonyosoma Wagl. 



One nasal; a loreal ; scales keeled ; teeth equal PhyUopltis Gthr. 



AA. Posterior maxillary tooth abruptly longer than those which precede it. 

 a. Maxillary tooth series uninterrupted (one i^reoculai ). 

 /3. Moderately elongate. 



Scales smooth ; two nasals ; a frenoorbital Nymphophidium Gthr. 



Scales keeled ; one loreal ; one j)reocular Jlerpeforeas Gthr. 



/?/?. Very slender. 

 y. Anal double. 



Scales keeled ; no loreal Leptophis^ Bell. 



Scales keeled ; a loreal Sapnidophrys Fisch. 



Scales smooth ; a loreal Philoihammis^" Smith. 



yy. Anal single. 



Scales smooth ; a loreal C//?orojj/fis' ' Hallow. 



aa. A toothless space in front of the long maxillary tooth. 

 /?. One preocular ; anal double. 

 y. Form very elongate. 



• Arizona Kenn. 



2 Cynophis Gray. Cnmpsosoma D. & B. Cnelognathun Fitz. Oeoptyas Stcind. 



^ Ileteronotus Hallow., nom. prreocc. hinc Glaniolentcs Cope. Lejonotux Jan. 



«Spec. Syn. Kept. 17G8, p. 73; Cope; Calopeltis Bp., 1840; Scotophis, B. & G., IRM ; Coluher Linn., 



Giinther, 1858. 

 ^ Dendrophidium Cope ; Xenurophis Gthr. 



• Coluher Dum., Garm. ; Masticophig B. &. G. 



^ Opheodry.1 Vitz, Cope. Fhilophyllophig Gaxm. 



^ Hydrophohui; Gthr. 



^Ahaitulla Gthr. Thrasnpa Hallow. 



^'' lihamnnphin Gthr. OaHtrnpyxis Cope. 



" Berpetathiopg Gthr. 



