SNAKES. 37 
** Labial shield occupying the front half of the lip; eyes over the 
fifth or sixth shield ; hinder part of the face covered with small 
scales ; ventral scales generally two-rowed, forming a heeled 
ridge, some united in pairs into six-sided shields. 
9. Hyprus. 
c. Body covered with smooth, polished, imbricate scales: head 
as large as the body: ventral shields rather large, trans- 
verse, smooth, folded together and keeled. 
10. TomocasteR. Head with regular shields ; superciliary shields 
simple ; ventral shields entire. 
11. SrepHaNonypRA. Head shields numerous ; superciliary shields 
3 or 4; ventral shields nicked behind. 
B. Head covered with scales, like the body : nostrils surrounded by a 
small, continuous ring: eyes surrounded by a series of small 
scales ; labial shields small, with a larger series above them: 
pupil round: ventral shields very small, scale-like, separated on 
each side of a keeled ridge. Rivers. Acrochordina. 
12. CuEersyprus. Tail compressed, sword-shaped, prehensile: 
body fusiform, covered with small rhombic scales, with a cen- 
tral tubercular keel. 
13. AcrocHorpus. ‘Tail conical, tapering, moderate: body fusi- 
form, covered with tricuspid scales. 
II. Tail conical, tapering. Belly rounded beneath, with more or less 
broad band-like shields. Rivers or ponds. 
A. Head shielded : tail scaly beneath : abdominal shields flat, small, 
sia-sided, with a keel on each side, as if formed of two united 
scales: nostrils in a ring of small scales: scales keeled, Erpe- 
tonina. 
14. Erpreton. 
B. Head shielded : tail with two series of shields beneath : nostrils 
between two shields: abdominal shields broad, keeled on each 
side : scales smooth. Bitiana. 
15. Brria. Head small. 
