Cope.] 490 [May 21, 



Two preocular plates Zabcys Cope. 



** One median dorsal row of scales. 

 f Body little or not compressed. 

 X Internasals not confluent with nasals. 

 a. Several loreal plates. 



Two or more preoculars Ptyas Cope. 



aa. One loreal (rarely two). 

 ,5. Four or more prefrontals. 



Anal entire ; scales keeled Pityophis Holbr. 



/?/?. Two prefrontals only. 

 v. Two nasal plates. 

 8. Anal entire. 



Scales smooth ; rostral produced Bhinechis* Mich. 



One preocular : rostral not produced Spilotes\ Wagl. 



88. Anal double. 

 s. One preocular. 



Form robust ; tail moderate Coluber% L. 



Form elongate ; tail long D)ymobius'S i Cope. 



Form very slender ; tail very long Dendrophis Boie 4 



e;. Two preoculars. 



Scales keeled Elaphis Aldv. 



Scales smooth Bascanium || B. & G-. 



yy. One nasal plate. 



Scales keeled ; a loreal plate Cyclopias^ Gthr. 



Scales smooth ; a loreal plate Liopeltis Cope. 



Scales smooth ; no loreal Phragmitophis Gthr. 



XX Internasals confluent with nasals. 



Scales smooth with one pit ; anal divided Symphimus Cope. 



\\ Body much compressed. 



One nasal plate ; a frenoorbital Dryocalamus Gthr. 



Two nasals ; a frenoorbital ; teeth equal Odontomua** D. & B. 



Two nasals ; loreal and preocular distinct Gonyosoma Wagl. 



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



AA. Posterior maxillary tooth abruptly longer than those which pre- 

 cede it. 

 a. Maxillary tooth series uninterrupted (one preocular). 

 ft. Moderately elongate. 



Scales smooth ; two nasals ; a frenoorbital Nympliopltidium Gthr. 



Scales keeled ; one loreal ; one preocular Herpetoreas Gthr. 



/?;?. Very slender. 



* Arizona Kenn. 



t Cynophis Gray. Compxosoma D. & B. Ccelognathus Fltz. Geoptyas Steind. 

 % Calopellis Bp. Grayiu Gthr. Heteronotus Hallow, noni. prueocc. liiuc Glanio- 

 lesles Cope. Lejonotus Jan. 

 '4 Dendrophidium Cope. 

 || Mastlcophis B. & G, 



\ Opheodrys Fltz., Cope. Philophyllophis Garni. 

 ** Hydroplwbus Gthr. 



