1886.] 4yd [Cope. 



II. Anterior maxillaries isolated. 

 a. Subeaudals in two rows. 

 ft. Nareal region with a pit. 



Scales smooth ; anal entire Bothrolycus Gthr. 



ft. No nareal pit. 

 j. Longest teeth at middle and posterior end of maxillary hone. 



Two nasals ; hody round Dinodon* D. & B. 



yy. Longest teeth at front of maxillary. 



Scales keeled ; two nasals ; a loreal Ophites Wagl. . 



Scales smooth ; two nasals ; a loreal Lycodon Boie. 



Scales smooth ; two nasals ; no loreal Tetragonosoma Gthr. 



Scales smooth ; one nasal ; a loreal Leptorkytaon Gthr. 



aa. Suhcaudal plates in one row. 



Scales keeled Cercaspis Wagl. 



Scales smooth Cyclocorus D. & B. 



Leptognathin^e. 



a. Suhcaudal scuta entire. 



Teeth of equal lengths Anoplodipsas Pet. 



Teeth elongate posteriorly Dipsadoboa Gthr. 



Teeth longer anteriorly Arnblycephalus Kuhl. 



aa. Suhcaudal scuta in two rows. 

 ft. A median geneial plate. 



Maxillary bone very short ; one nasal plate Astlienodipsas Pet. 



Maxillary hone long ; two nasal plates Mesopeltis\ Cope. 



ftft. No median geneial plate. 



Teeth weak ; equal ; two nasals Leptognathus D. & B . 



Teeth longer in front ; one nasal Pareas Wagl. 



DlPSADINiE. 



I. Suhcaudal scuta. 



Parietal plates replaced by scales; other plates normal. .Pythonodipsas Gthr. 



II. Subcaudal scuteila. 



a. No teeth anterior to the grooved maxillary. 



Scales smooth Opist7ioplus Pet. 



aa. Median maxillary teeth not much shortened. 

 Nostril large, between two nasals and the internasal ; vertebral scales 



larger Rhinobothryum Wagl. 



Two nasals enclosing nostril ; body elongate, compressed, anal entire ; 



vertebrals generally larger Dipsas% Laur. 



Two nasals enclosing nostril ; body less compressed ; anal double ; verte- 

 bral row not larger ; one loreal Sibonfy Fitz- 



* Eumesodon Cope. 

 t Aslhenognalhus Boc. 



% holga Fitz. Triglyphodon et Himantodes D. & B. Eudipsas Gthr. Toxi- 

 codryas Hallow. 

 Crotaphopellis Fitz. LepLodira Gthr. 



