4 HEER F. E. BLAAUW ON CATOBLEPAS GNU. [Jan. 15, 
fig C) the frontal or basal parts begin to show, whilst the hairy 
intermediate part (a-), fig. C) gets narrower and narrower until at 
the age of two years little of it is left. As the animal gets older 
this ‘nairy region becomes restricted to a narrow space of from 2 to 
4 em. in width, and is generally narrowest in the males, as in them 
the horns acquire their greatest development. Until the age of about 
two years the frontal parts (a 6, fig. C) are quite smooth; but after 
this time the roughness which the adults present on these parts begins 
to appear in the following manner :—At first lougitudinal fissures or 
Horns of Catoblepas gnu. Adult female. 
cracks begin to show, which are gradually cut through by vertical 
fissures, so that little squares are formed. These soon begin to loosen 
themselves partially from their bases in such a way that the part 
furthest from the centre of the front keeps fast, whilst the opposite 
parts get more or less loose and turned up, so that a kind of rough 
irregular scales is formed. 
“Whilst the straight parts of the horn are growing, the horny 
covering or sheath comes off comparatively easily ; and it is manifest. 
that the interior with its blood-vessels runs quite up to the top of 
it. Afterwards the straight points in great part get quite massive 
and horny ; and after this there is little danger of their being broken 
off, unless by the animal repeatedly rubbing itself against hard 
stones &c., as it often does when confined in a narrow space. 
