246 ZOOLOGICAL RESULTS OF THE RUWENZORI EXPEDITION. 
Family COLUBRID. 
11. CuLororais EMINI Gthr. 
Mubuku Valley, E. Ruwenzori, 5000 feet. 
12. Nata NIGRICOLLIS Reinh. 
Mokia, S.E. Ruwenzori, 3400 feet. 
Family VIPERID &. 
13. ATHERIS woosNAMI Blgr. (Plate IX.) 
Bouleng. Ann. & Mag. N. H. (7) xviii. 1906, p. 37. 
In shape the head resembles that of Vipera berus, being more clongate than in the 
other species of Atheris, truncate at the end, and provided with a sharp canthus 
rostralis; the eye is rather small, its diameter about half the length of the snout in 
the adult. The end of the snout below the canthus rostralis and between the nasal 
and first labial shields is covered by four smooth shields: a rostral, which is twice and 
a half to three times as broad as deep, and above it three shields in a row, the median 
of which may be regarded as detached from a rostral such as exists in a typical Viper. 
The scales on the snout and vertex may be smooth or more or less strongly keeled, 
further back they are all strongly keeled ; there are 8 to 10 across the crown from eye 
to eye and 12 to 15 round the eye, which is separated from the upper labials by one 
or two series of scales; the upper labials number 10 on each side ; there are 3 or 4 
pairs of small chin-shields, the anterior largest and in contact with 5 or 4 lower labials; 
unlike those of the other Atheris, the gular scales are smooth or very faintly keeled. 
The highest number of scales across the body varies between 25 and 30; all are 
strongly keeled. Ventrals 151 in males, 158 to 162 in females; anal entire ; sub- 
caudals 49 to 52 in males, 44 to 47 in females *. 
In coloration as well as in form and scaling this Atheris departs less than its con- 
eeners from the typical Viper pattern, the characteristic zigzag dorsal band and the 
reversed initial (W) on the head being present in some specimens. The ground-colour 
varies from olive-green to bright grass-green above, from yellowish to pale green 
beneath ; the keels of most of the scales are black, and the upper head-scales are edged 
with black ; there is usually a dorsal series of large black rhombs, which may be con- 
fluent into a zigzag band, and a lateral series of smaller black spots; a A- or A-shaped 
black marking on the top of the head, the apex between the eyes; a black streak on 
* In the large series of Atheris chloroechis and A. sguamiger in the British Museum, which renders the 
distinction of these two supposed species an almost impossible task, the variation in the number of ventrals 
ranges between 145 and 165 for males, 152 and 176 for females, and that of subeaudals between 52 and 65 for 
males, 46 and 59 for females. 
