84 EEPTILES. 



d. Scales keeled ; labial shields not pitted ; nostrils in a sin- 

 gle plate. Asia. 



16. Enygrus. Head covered with small irregular shields ; nostrils 

 in a single plate. Asiatic Islands. 



17. Casarea. Head scaly; muzzle covered with symmetrical 

 shields ; nostrils in a single plate ? 



18. BoLYERiA. Head covered with symmetrical shields ; nostrils in 



a single plate. 



II. Tail very shorty slightly or not prehensile. Head indistinct^ 



short. 



a. Head covered with scales ; pupil oblong ; scales convex ; 

 suhcaudal shield one-roived ; intermaxillary teeth none ; 

 supra-orbital bone none. Erycina. 



19. CusoRiA. Muzzle rounded ; ventral and subcaudal plates nar- 



row ; scales ovate, of body and tail smooth. 



20. GoNGYLOPHis. Muzzle wedge-shaped ; jaws equal ; head with 

 small keeled scales ; scales of back keeled ; body fusiforai. 



21. Eryx. Muzzle wedge-shaped ; upper jaw largest ; head with 

 small scales ; scales of back smooth, of hinder part of body 

 keeled. 



22. Clothonia. Muzzle wedge-shaped ; upper jaw largest ; scales 



smooth. 



b. Head shielded; pupil round. 



* Nostrils in a single shield ; eyes surrounded by shields ; intermax- 

 illary teeth none. Cylindrophina. 



23. Cylindeophis. 



** Nostrils between two shields ; eyes surrounded by small scales. 



Charinina. 



24. Charina. 



*** Nostrils between two shields ; eyes in a single shield ; intermax- 

 illary teeth distinct Tortricina. 



25. TOETRIX. 



