18 SYNOPSES AND DESCRIPTIONS. 
SIBON TORQUATUM. 
LEPTODEIRA TORQUATA Giinther, 1860, Ann. & Mag. Nat. Hist., pl. X, 169. 
Posterior maxillary tooth larger, separated by an interspace. Scales in 
21 rows. Ventrals 174. Anal bifid. Subcaudals 44—56. Total length 
16 in. 51.; tail 3 inches. Total length 17 in. 51.; tail 2 in. 31. 
Brownish-grey, with a vertebral series of brown spots, some of which 
are confluent into a zigzag band; neck with a white collar, behind which 
there is a large brownish-black blotch, Hab, Nicaragua; Island of Laguna, 
(From Giinther.) 
SIBON DISCOLOR. 
LEPTODEIRA DISCOLOR Giinther, 1860, Pr. Zool. Soc. Lond., 317. 
Posterior maxillary tooth larger, in a continuous series with the other 
teeth, not grooved. Scales in 19 rows, smooth, rhombic, those of the sides 
similar to those of the back. Ventrals 179—182. Anal bifid. Subeaudals 
87—88. Total length 21 in. 11.; tail 6 in. 
Dirty white, with numerous black cross-bands extending on to the ven- 
tral plates; belly uniform whitish. Fifty-one to fifty-four black bands cross 
the trunk and extend to the edge of the belly; they are broader than the 
interspaces between, and become interrupted and spot-like on the tail. 
Upper part of head brown, with a whitish collar behind the occipitals. 
Separated from S. annulatum by the teeth. Hab, Oaxaca, Mex, (From 
Giinther.) 
SCYTALINAE. 
Moderate, cylindrical to subeylindrical; head distinct from the neck, 
broad behind, crown flat; tail medium, tapering. Eye medium, pupil 
oblong or elliptical. -Crown-shields nine. Nasal generally divided. A 
loreal. Preoculars one to two. Postoculars two. Posterior maxillary 
teeth longer, grooved. Scales smooth, in 17 to 19 rows, occasionally the 
vertebral series larger. Anal entire. Subcaudals simple or bitid. 
OXYRHOPUS. 
Wagler, 1830. 
Elongate and subeylindrical to slender and slightly compressed; head 
moderate, a little larger than the neck, depressed, muzzle rather broad, 
crown flat; tail short to moderate. Eye medium, pupil elliptical, erect. 
