52 HYDROPHIS NIGROCINCTA. 
two post-oculars; three temporal shields on the side of each occipital. 
Two pairs of chin-shields, the anterior of which are in contact with each 
other. Twenty-seven to twenty-nine series of scales round the neck. 
Scales imbricate, rhombic, keeled ; those on the highest side of the body 
as broad as long. Ventrals distinct, not quite twice as broad as the 
scales of the adjoining series ; smooth ; 320-331 in number. Four large 
anal-shields. The tail terminates in a large scale. The trunk is 
encircled by 43(53-)-61 complete rings of black colour. The width of 
these rings is equal on the sides and on the belly; on the vertebral 
line only they are a little broader; they are narrower than the inter- 
spaces, which occupy from four to five transverse series of scales, whilst 
a black ring occupies only three. The interspaces are greenish-olive on 
the back, yellowish on the sides and on the belly. The crown of the 
head and the upper lip are blackish, a yellow band running along the 
whole upper margin of the head; lower jaw whitish. Tail with from 
nine to eleven black cross-bars.” 
