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! 1 
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 
of horns in the Isabelline 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 
Isabelline Gazelle. 
Very young male. 
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— i.e., on north and south respectively. 
