12 SYNOPSES AND DESCRIPTIONS. 
Teeth equal, smooth ; 
anal entire; scales in 13-17 rows, 
vertebral series larger 
LEPTOGNATHUS. 
Posterior maxillary teeth longer, grooved; 
anal entire; scales in 19-27 rows, 
vertebral series larger 
Dipsas. 
anal divided, rarely entire; scales in 19-23 rows, 
dorsal series similar 
SIBON. 
LEPTOGNATHUS. 
Duméril, 1852. 
Body long, more or less compressed; head subquadrangular, high, dis- 
tinct from neck; tail medium. Eye moderate, pupil erect. Teeth equal, 
smooth. Head-shields nine, short, broad. Rostral broad, low. With or 
without a distinct loreal. Orbitals 1—2+2—3, suborbitals sometimes 
present. Scales moderate, rarely keeled, in 13-17 rows, vertebral gener- 
aily larger. Anal rarely divided. Subcaudals in two rows. 
Hab. Mexico to the Argentine Republic; India. 
Seales keeled in vertebral series, rows 15-17; 
loreal distinct fasciatus. 
Seales smooth, rows 17; 
loreal distinet dumérilit. 
Seales smooth, rows 15; 
loreal and anteorbital fused ; 
transverse bands narrow nebulatus. 
transverse bands broad dimidiatus. 
LEPTOGNATHUS FASCIATUS. 
TroPrpopipsas FASCIATA, Gihr., 1858, Cat. Col. Snakes, 181. 
Slender; head oval, crown slightly flattened, muzzle broad; tail long, 
slender. Eye large, pupil erect. Head-shields broad. Frontals bent on 
the side. A loreal. Orbitals 2-2. Temporals 14+2. Labials 6-7, penult- 
imate largest. Infralabials 7, fifth largest. Submentals two or three 
