in the Collection of the British Museum. 415 
Xenocalamus bicolor, Pl. XIX. figs. A. 
The principal ‘characters by which this interesting snake 
may be recognized at once are contained in the generic dia- 
gnosis, and may be completed thus :— 
The vertical shield is the largest shield of the head, six- 
sided, with an obtuse angle in front and a pointed one behind ; 
the occipitals are comparatively small, ovate shields, forming 
only a very short suture behind the vertical. The nostril is 
situated between two shields, the anterior being very small, 
the posterior elongate, similar im form and size to the pre- 
ocular; supraorbital and postocular very small; six upper 
labials, the anterior very small, the third and fourth entering 
the orbit, the fifth forming a long suture with the occipital, 
and larger than any of the other labials, the sixth very small 
again; one large temporal ; five lower labials besides the small 
anterior median shield; the first pair of lower labials form a 
suture behind the median labial; the second small; the third 
very large, as long as the others together; a single pair of 
narrow lanceolate chin-shields. Ventrals 219. 
- Upper parts uniform black ; lower parts and the two outer 
series of scales uniform white. I have examined a single 
Sea 17 inches long (tail mutilated), found by Mr. J. 
hapman on the Zambeze. 
The three figures on Pl. XIX. represent the head, of twice 
the natural size. : 
Geophis elaps (Gthr.). 
Rhabdosoma brevifrenatum, Jan. 
_ We have received this snake recently also from Pebas. 
Geophis latifrons. Pl. XIX. figs. B. 
Scales in seventeen rows. Ventrals 155; anal entire; sub- 
caudals thirty-six. Upper labials six, the third and fourth 
entering the orbit; two postoculars; temporals 1+2; one 
pair of chin-shields in contact with four labials. Vertical 
mary broad, broader than long, with the lateral edges short 
and convergent ; frontals longest in their transverse diameter. 
Head and neck black, with a yellow ring across the pos- 
terior half of the occipitals and the temporal shields. Body 
_ encircled by ten pairs of black rings, each ring being as broad 
as the red interspace. Each scale of the red interspace with 
a black tip; tail with two pairs of similar rings. 
One specimen has been sent from Pebas by Mr. Hauxwell, 
a correspondent of Mr. Bates. It is 10 inches long, the head 
being 4 lines, the tail 18 lines. 
