4 HEER F. E. BLAAUW ON CATOBLEPAS GNU. [Jail. 15, 



fig C) the frontal or basal parts begin to show, whilst the hairy 

 nitermediate part {a-b, fijj;. C) gets narrower and narrower nntil 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 cm. 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 b, 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 longitudinal fissures or 



Fi-. D. 



Horns of Catohlepas 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 7-ough 

 irregular scales is formed. 



" Whilst the straight parts of the horn are growing, the horny 

 covering or sheath comes otf comparatively easily ; and it is manifest 

 that the interior with its blood-vessels runs quite up to the top of 

 it. Afterwards the straijiht 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. 



