36 REPTILES. 



a. Scales square or six-sided^ placed side by side. 



* Head elongate^ depressed. 

 1. Pel AMIS. 



** Head moderate^ rather compressed ; gape moderate. 



2. Lapemis. Head moderate, short, rounded in front ; dorsal 



scales square ; ventral shield broad, six-sided. 



3. Aturia. Head moderate, short, rounded in front ; dorsal scales 



six-sided ; ventral shield six-sided. 



4. MicRocEPHALOPHis. Head small ; scales six-sided ; ventral 



scales keeled. 



b. Scales ovate, six-sided, imbricate, keeled, or with the keel 

 reduced to a tubercle on the centre of the scales : head 

 and gape moderate. 



* Labial shields occupying the greater part of the lips ; the eyes over 

 the fourth, or rarely over the third, or the fourth or fifth shield : 

 ventral shield united. 



5. Enhydeina. Rostral plates narrow, erect ; lower linear, sunken ; 



nasal narrowed in fr'ont : ventral shield iiat : head moderate, 

 short ; eves moderate. 



6. Hydrophis. Rostral broad, transverse; lower triangular; nasal 



truncated or notched in front : ventral shield flat : head short ; 

 eyes small. 



7. Chitulia. Rostral broad, transverse; lower triangular ; nasal 



truncated or notched in fr'ont ; ventral shields flat : head elon- 

 gate, depressed ; eyes large. 



8. Kerilia. Rostral broad, transverse; lower triangular; nasal 



truncated in front: ventral shield broad, convex, foiTaing a 

 slight keeled ridge ; the hinder ones with a keel on each side : 

 head short, shelving : scales veiy large, broad, six-sided : eyes 

 rather large, over third and fourth labial shields. 



