246 ZOOLOGICAL EESULTS OF THE EUWENZOEI EXPEDITION. 



Family CoLUERiDiE. 



11. Chlokophis emini Gthr. 



Mubuku Valley, E. Ruwenzori, 5000 feet. 



12. Nata nigeicollis Reinh. 

 Mokia, S.E. Ruwenzori, 3400 feet. 



Family Viperid^. 



13. Atheris woosnawi Blgr. (Plate IX.) 

 Bouleiig. Ann. & Mag. N. H. (7) xviii. 190G, p. 37. 



In shape the head resembles that of Vipera herus, being more elongate 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 3 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- 

 geners from the typical Viper pattern, the characteristic zigzag dorsal band and the 

 reversed initial (V) 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 cMoroecliis and A. squamiger 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 subcaudals between 52 and 65 for 

 males, '16 and 59 for females. 



