Cope.l 490 (May 21, 



ACOXTIOPHID.E. 



Rostral plate deeply grooved below ; nasal single ; cephalic plates nor- 

 mal ; scales smooth ; body round ; teeth, the posterior longest, not 

 grooved Acontiophu Gthr. 



PROTEROGLYPHA. 



HYDROPHID^.* 



I. Gastrosteges wide, flat. 



Two pairs of frontal shields Platurus Latr 



II. Gastrosteges wide, with two keels. 



Scales imbricate ; one nasal Aepysun/s Lacep. 



Top of head scaly ; two nasals Pelagoplm Pet. & Dor 



III. Gastrosteges narrow, rudimentary, or absent. 

 * Xasals separated by frontals. 



Gastrosteges distinct to vent Distira Lacep 



** Nasals contiguous. 



Head covered with scales behind Acalyptus D. & B. 



Head short, entirely shielded ; no symphyseal notch. . . . HydropMs Daud. 

 Head moderate, entirely shielded ; a deep symphyseal notch 



Enhydrina Gray. 

 Snout long, spatulate Pelamis Daud. 



NAJID.E. 



I. Grooved teeth behind two perforated teeth on the os maxillare. 

 Head-shields normal ; no loreal ; scales smooth ; form fusiform 



Ogmodonf Pet. 



II. Solid teeth behind the fang on the os maxillare. 

 A. Loreal plate present. 



Subcaudals entire ; scales smooth Denisonia Krefft. 



AA. Loreal plate absent. 

 a. The neck with few scales, not extensible. 

 /?. Subcaudal scuta one-rowed. 

 y. Scales of vertebral row equal to others. 



Nasals two ; scales smooth ; anal bifid Pseudechix Wagl. 



One nasal ; scales smooth ; anal single Uoplocephalus\ Cuv. 



One nasal ; scales keeled ; anal single Tropidechis Gthr. 



aa. Scales of vertebral line enlarged. 



Scales smooth ; two nasals ; anal entire Bungarns Daud. 



ftp, Subcaudal scuta two-rowed. 



*This table is mostly from Gunther, Reptiles Brit. India, 355. 

 t Labionaris Brocclii. 

 I AIi do Wagl. 



