38 . REPTILES. 
C. Head shielded: scales striated, and keeled or smooth: tail co- 
nical, tapering, with two series of shields beneath : nostrils in 
centre of a large nasal shield, with a groove to the outer side : 
ventral shields rounded (or rarely slightly keeled on the sides ) ; 
frontal shields 3, rarely 2 or 4, all small. Cerberina. 
a. Crown scaly ; occipital rudimentary ; frontals 4; anterior 
pair very small. 
16. Cerserus. Scales keeled, striated ; hinder labial shield low. 
b. Crown shielded ; occipital moderate. 
* Head distinct, depressed ; frontals 4; anterior pair small ; rostral 
rounded. 
17. Feranta. Scales smooth; seventh upper labial low, with a 
large shield over it. 
** Head distinct, depressed ; frontals 3; anterior transverse ; rostral 
rounded . 
+ Fourth and fifth hinder labial shields small or divided. 
18. Homatopsis. Scales keeled. 
19. Puyrouopsis. Scales smooth. 
++ Hinder labial large, like others ; scales keeled ; rostral rounded. 
20. Uranors. Scales truncated, strongly keeled, striated; eye 
over fourth shield. 
21. TacnynectEs. Scales truncated, strongly keeled. 
22. Troprpopuis. Scales ovate, keeled, striated; eye over fourth 
and fifth shield. 
23. Myron. Scales ovate, slightly keeled, smooth. 
24. Hexicops. Scales ovate, polished; of back and tail keeled. 
