Cope.] 4 JO [ May 2 J, 



Subcaudal and anal plates double ; scales keeled; rostral normal 



Causus "Wagl. 

 Subcaudals and anal entire ; scales smooth ; rostral normal ; a loreal 



Dinodipsas Pet. 



ATRACTASPIDID^E. 



Head not distinct ; two nasals ; a loreal ; scales smooth; subcaudals entire 



Atractaspis Smith. 



VIPERID,^. 



I. Urosteges two-rowed. 



Nostril between two plates. Vipera* Laur. 



"Nostril between three plates " (Gthr.) Daboia Gray. 



Nostril surrounded by scales and a nasal ; horn-like supraocular scales 



Cerastes Wagl. 

 Nostril surrounded by scales and a supranasal ; no supraocular nor nasal 



horns , Bitis-f Gray. 



Nostril surrounded by scales and a supranasal ; horn-like scales above 

 latter ; no supraocular horns Glotho Gray. 



II. Urosteges one-rowed. 



Body and tail cylindric EcMs% Merr. 



Body and tail compressed and prehensile Atheris% Cope. 



• 



CROTALID^. 



I. No rattle. 

 ft. Urosteges two-rowed. 

 Top ot head scaled ; urosteges four-rowed at end ; a caudal spine 



Laehesis Wagl. 



Top of head with small scales ; tail normal .Bothrops\ Wagl. 



Top of head with large imbricate shield-like scales Peltopelor Gthr. 



Top of muzzle scaled ; rest of head shielded Hypnale Cope. 



Top of head with nine shields ; scales carinate Trigonocephalus Oppel. 



Top of head with nine shields ; scales smooth Calloselasma\ Cope. 



ftft. Urosteges one-rowed. 



Body and tail cylindric, not prehensile ; head scaly Bothriopsis Pet. 



Body and tail compressed, prehensile : head scaly, scales normal 



Botkrieclus Pet. 

 Body and tail compressed, prehensile ; head scaly ; a row of scales out- 

 side the superciliary shield Teleuraspis Cope. 



*Pelias Wagl. 



t Echidna Wagl. not Forster. 

 % Toxicoa Gray. 

 ? Poeciloslolus Gthr. 



|| Trimesurus Gray, Gthr., Peters. Tropidolccmus Wagler. Megwra Gray. 

 Atropos Wagl. 

 1T Leiolepis J). & B. nee Cuy. 



