Proceedings of the Zoological Society of London, forerunner of Journal of Zoology, includes many fascinating first descriptions of species unknown to science. In our latest Hidden Gem we share E. Ray Lankester’s 1901 report on Sir Harry Johnston’s discovery of the okapi in ‘On Okapia, a new Genus of Giraffidae, from Central Africa’. Sir Harry Johnston first became aware of okapi from Sir Henry Stanley’s In Darkest Africa, in which Stanley mentions that Wambutti natives referred to a donkey, called ‘Atti’, which they occasionally caught in pits. When Johnston rescued a group of Congolese pygmies from abduction by a German showman, they apparently rewarded him with tales of a horse-like mammal, and eventually showed him tracks of this elusive forest species. However, it was not until Johnston received a complete skin with double hoof-bones that he was able to deduce that the okapi belonged to the group of Artiodactyle ungulates, and on examination of two skulls he concluded that the okapi is closely related to giraffe. In addition to the detailed first description of okapi, there is a beautiful drawing showing the arrangement of the hair upon the frontal and basinasal regions of the okapi’s head (Text-fig 14). The illustration of Okapia johnstoni shown here, drawn from the skin by Pierre Jacques Smit (1863–1960), is also included in the paper.