The sable-antelope, the gems-bok, the oryx, the hart-beest, the bonte-bok, and the addax have each peculiar white markings; and they are besides characterised by horns so remarkably different in each species and so conspicuous, that it seems probable that the peculiarities in length, twist, and curvature have been differentiated for the purpose of recognition, rather than for any speciality of defence in species whose general habits are so similar.
[Illustration: FIG.

18 .-- Gazella soemmerringi.] It is interesting to note that these markings for recognition are very slightly developed in the antelopes of the woods and marshes.

Thus, the grys-bok is nearly uniform in colour, except the long black-tipped ears; and it frequents the wooded mountains.

The duyker-bok and the rhoode-bok are wary bush-haunters, and have no marks but the small white patch behind.

The wood-haunting bosch-bok goes in pairs, and has hardly any distinctive marks on its dusky chestnut coat, but the male alone is horned.