SNAKES. 83 



4. LiASis. Upper and lower labial shields pitted; muzzle and 

 space between the eyes shielded. 



5. Nardoa. Lower labial shields pitted; crown with eleven sjth- 

 metrical shields. 



B. Subcaudal plates entire, one-rowed ; intermaxillary or incisive 

 teeth none ; superorbital line none. 



a. Scales smooth ; labial shields pitted. 



6. Epicrates. Forehead w^ith symmetrical shields ; crown scaly. 

 America. 



7. XiPHosoMA. Forehead and crown scaly; muzzle with regular 

 shields ; labial plates short and all pitted. America. 



8. CoRALLCs. Forehead and crown scaly ; muzzle with regular 



shields ; labial shields short, hinder ones pitted. America. 



9. Sanzixia. Forehead and crown scaly ; muzzle with regular 



shields ; labial shields elongate, prismatic. Madagascar. 



JO. Cliftia. Forehead and crown scaly; muzzle with regular 

 shields ; labial shields broad, low. Asia. 



b. Scales smooth ; labial shields smooth, not pitted. 



1 1 . Boa. Crown covered with scales ; nostrils lateral, between two 



plates. America. 



12. Pelophilus. Crown covered with irregular plates ; nostrils 

 lateral, between two scales. America. 



13. EuNECTES. Crown covered with irregular shields ; nostrils 

 vertical, between three plates. America. 



14. Chilabothrus. Crown covered with regular shields ; nostrils 

 lateral, between three scales. Madagascar. 



c. Scales keeled; labial shields not pitted ; nostrils between 

 two plates. America. 



15. Ungalia. Head covered with s^Tumetrical shields. 



