338 SAVAGE SUDAN 



problem presents a double example. First, in this Sudan 

 reedbuck, we find a clear (and deceptive!) dimorphism as 

 between younger animals and their own parents. For in 

 the young the horns assume a shape and set which is 

 totally different from that acquired when at full maturity. 

 This involves not merely a change in the horn itself but 

 in the solid bone-core of the skull. Secondly, these horns 

 during immaturity so exactly mimic in form those of 

 adult reedbucks of a totally distinct and geographically 

 distant race (the Bohor), as to deceive the very elect ! l 



Again, it might appear well nigh impossible at least 

 as we blindly regard such things that solid bone (being 

 an integral part of the skull) could con- 

 tinue during several years to alter its 

 shape. But it does do so. We had, 

 of course, previous evidence of the fact 

 in the gnus and many other antelopes ; 

 while recently I discovered that a 

 similar development occurs with the 

 horns of the desert gazelles of Sudan. 

 The annexed sketch shows the form 



ISABELLINE GAZELLE. r , , , . ... ., 



Very young male. ' horns in the Isabcllme gazelle 

 during its period of immaturity. 



Reedbuck are essentially nocturnal in habit. The 

 following summary of their daily lives is extracted from 

 my diary : " They feed early and late but lie up by day. 

 On dull cloudy mornings some reedbuck may remain 

 visible in the open for an hour or even two after sun- 

 rise ; but on bright hot days they seek shelter earlier often 

 by dawn couching in the deep grass, preferably beneath 

 a bush or a tree, when the horns may reveal their position 

 to an extra keen eye. If they drink in the morning it 

 must be before day-dawn ; but in the evenings I see 



1 The case is even stronger, since in the interposed zone of Equatoria, 

 there co-exist not one but two quite distinct species of reedbuck (the Bohor 

 and Chanler's), both of which affect the short, thick-set, and heavily hooked 

 type of horn, though geographically placed midway between the two long- 

 horned races on either side of them /.*., on north and south respectively. 



