Snout broad, much depressed, long, spatulate, with the upper lip swollen, and without "canthus rostralis". Rostral shield very low, broad, slightly bent backwards on the upper surface of the snout; anterior frontals [= internasals] very small; posterior frontals [= prefrontals] longer than broad, much more so in adult specimens than in young ones; there is a lateral notch between the anterior and posterior frontals, in which the inner anterior angle of the loreal is received; the posterior frontals have an obtuse lateral angle corresponding to the suture between loreal and praeocular; occipitals elongate. Nostril small, directed upwards, between two nasals, the anterior of which is situated on the foremost part of the snout. Loreal single, large, nearly twice as long as broad. Praeocular single, in contact with the vertical [= frontal] and with the third labial; specimens in which it does not reach the vertical are very scarce. Two postoculars; supraciliary rather small. Nine upper labials, the third, fourth, and fifth of which enter the orbit. Temporals numerous, scale-like. Scales smooth, with a minute apical groove, in seventeen rows. Abdomen and tail with an angular ridge on each side. Ventrals 183-209; anal bifid, in a few specimens entire; subcaudals 57-77. Each maxillary is armed with two fangs in front, placed in a transverse line, the outer being much larger than the inner; the lateral longitudinal series of teeth commences at some distance from the fangs; they are small, from four to twelve in number, the last being considerably larger than the others; pterygoido-palatine teeth small, of equal size;