 nasals ; 
in the Collection of the British Museum. 423 
osterior edge of which is rather irregular ; loreal as high as 
ong; two preoculars, the upper of which contributes to the 
canthus rostralis, extending to the upper side of the head, but 
not by some distance reaching the vertical; two postoculars ; 
eight upper labials, the fifth only entering the orbit ; temporal 
shields small, irregular. 
The median lower labial shield is extremely narrow; the 
chin-shields of nearly the same length, the anterior in contact 
with four or five labials. 
_ Greyish olive; many of the scales, especially on the hinder 
part of the trunk, with a dark or blackish dot, a blackish 
streak through the eye; lower parts nearly uniform whitish. 
A single specimen has been sent by Dr. Kirk from Zanzibar. 
It is 15 inches long; length of the head 63 lines, of the tail 
4 inches. 
Rhagerrhis triteniata. Pl. XIX. figs. H. 
I have been in some doubt as regards the systematic posi- 
tion of this snake. Although it evidently belongs to the group 
of Psammophids, it does not perfectly agree with any of the 
nera. Having the coloration of a true Psammophis, it differs 
m the species of this genus in its dentition, in which cha- 
racter it agrees with Rhagerrhis; but the rostral shield is not 
so much produced—scarcely more than in Celopeltis, from 
which it differs in the structure of the scales. 
Head rather short, scarcely distinct from neck; body and 
tail moderately slender. Eye of moderate size; rostral shield 
as high as long, extending to the upper surface of the head, 
slightly advancing between the anterior frontals; anterior 
frontals not very much smaller than posterior ; vertical narrow, 
rather longer than the snout, and conspicuously longer than 
the a aaery which are obliquely truncated behind; two 
oreal square; preorbital single, slightly concave, not 
quite reaching the vertical; two postoculars; eight upper 
labial shields, the fourth and fifth entering the orbit; tempo- 
Bets two pairs of chin-shields, nearly equal in 
ength. 
Scales smooth, much imbricate, in seventeen rows, with a 
small apical groove. Ventrals 161; anal bifid; subcaudals 61. 
__ Brownish olive, with three dark-brown bands edged with 
black. The median band occupies the vertebral series and the 
halves of the adjoining series of scales, a white line running 
along its middle; this band commences immediately behind 
the occipitals, and terminates in the anterior part of the tail. 
_ The lateral band runs along the third and fourth outer series 
and the halves of the adjoining series of scales, commencing 
