the Butterflies of the White Nile. 15 



visit its snake-like branches were leafless and flowerless. 

 Several days out of our twenty-four were spent in the 

 Sadd.* Here the mass of the vegetation for many miles 

 at a stretch was made up of the dark green Papyrus 

 (Cyperus) anfiquorum with its beautiful umbels six feet 

 across, and of " um suf," or " mother of wool "-r-Vossia 

 procera — a reed-like plant, together with the more familiar 

 Phragmites communis. Of smaller plants growing beneath 

 the Papyrus at the water's edge a yellow composite and 

 a blue-purple Convolvulus or Ipomaea were the commonest. 

 The first " Candelabra " Euphorbia, striking trees nearly 

 twenty feet high, were seen on the island of Hillet al- 

 Nuwer [Lat. 8° 13' N.]. At Bor [Lat. 6° 13' N.], my 

 attention was called to the singular Kigelia aethiopica, Deer., 

 a tree belonging to the Nat. Ord. Bignoniaceae, which has 

 fiowerstalks many feet in length from which hang the 

 large rich brown-purple flowers and cucumber-like fruits, 

 the latter a foot long. At Rejaf [Lat. 4° 45' N.] a yet more 

 tropical-looking plant was the Aderiium coetaneum, Stapf. 

 [Nat. Ord. Apocijnaceae\ with its absurdly thick stems, 

 fleshy emarginate leaves, and clusters of showy bright- 

 red waxy flowers. Palms were rarely seen. Doubtless 

 this somewhat monotonous vegetation largely explains 

 the restricted Butterfly Fauna. 



The practice of burning the rank vegetation of the 

 Sadd, must have a very destructive effect upon insect life. 

 The numerous semi-calcined shells of such Gasteropods 

 as Burtoa and Limicolaria — genera frequenting trees or 

 bushes — -which are seen in many localities, prove that these 

 fires carry their destruction beyond the grassy areas on 

 which antelopes, giraffes and elephants still roam even 

 within sight of the steamer. 



The circumstance that nearly every tree and shrub met 

 with is more or less prickly tends greatly to protect butter- 

 flies from the collector's net. Near Ad-Duwem I came 

 across a grass even worse than the Indian " spear-grass," 

 for its prickly awns at a touch converted the net into a 

 tangled mass, which required some minutes to unravel. 

 Fortunately its distribution appears to be restricted to 

 a very small area. 



Shortly, the district to be dealt with includes Khartum 

 [Lat. 15° 37' N., Long. 32° 31' E.] and the countrv adjacent 

 to the banks of the White Nile to Lake No [Lat. 9° 30' N.] ; 

 * The correct spelling : pronounced Sudd. 



