Kaffir (Xhosa) Folk-Lore, by George McCall Theal, [1886], at sacred-texts.com
THE GIRL AND THE MBULU.
The mbulu is a fabulous creature, firmly believed in by little folks. It can assume the human form, but cannot part with its tail. One of its peculiarities is that it never speaks the truth wben it is possible to tell a falsehood.