Deep amid the tropical swamps of the Ituri Forest live some of the few remaining wild populations of the mysterious okapi. This gentle herbivore is the giraffe's closest modern relative. It was only discovered by scientists less than a decade before the 1909 launch of the Congo Expedition. Even today, the life history and daily habits of the animal are little understood. But in the first decade of the century, the okapi occupied an almost unicorn-like place in the popular imagination. With a tongue long enough to lick its own eyes, hind flanks striped like those of a zebra, and hearing so finely honed that it could sense and elude app...