344 
SAVAGE SUDAN 
is found as far as Jebel Mokram, near Kassala, but 
no farther, since exactly at that point it is replaced 
by the Isabelline and Dorcas gazelles. Southward it 
crosses the Settite but, somewhere in the neighbourhood 
of Gallabat, gives way to the red-fronted gazelle. For 
these details I am indebted to Bimbashi O’Callaghan, 
of the Egyptian Army, for some time stationed at 
Kassala, and my cabin-mate homewards in 1914. 
Elsewhere in this book are given several instances of 
singularly interrupted distribution. Two curious examples 
occur among the gazelle-tribe along the western bank of 
White Nile. 
From El Dueim, a village on the White Nile 120 
miles south of Khartoum, starts the old-time caravan- 
route winding away across the deserts for 130 miles to El 
Obeid. The traveller at first crosses a bush-clad riverain 
belt of 15 miles in breadth, upon which strip all the 
gazelles seen are red-fronted. But at that precisely 
defined point the red-front stops dead ; and beyond it, 
all the gazelles are Dorcas! The latter species then 
occupies by itself a stretch of 100 miles, across to a place 
called Taweel, 115 miles west of Nile. Thereat the 
Dorcas stops as abruptly as it began and the red-fronted 
gazelle reappears. 
Each species restricts itself exclusively to its 
own apportioned zone, and never are the two seen 
intermingled. 
The second, and parallel instance, refers to the addra 
gazelle, and by a curious coincidence occurs in precisely 
the same region—-that is, in the deserts west of El 
Dueim. 
Now to every big-game hunter in Sudan the 
addra represents a prize; but a prize not to be 
gained save at a stiff price. To reach its desert-home 
involves a long and wearisome trek by camelry into 
Sahara—save in the single isolated case about to be 
mentioned. 
