Heb. dishon, "springing", (Deut. 14:5), one of the animals permitted for food. It is supposed to be the Antelope addax. It is described as "a large animal, over 3 1/2 feet high at the shoulder, and, with its gently-twisted horns, 2 1/2 feet long. Its colour is pure white, with the exception of a short black mane, and a tinge of tawny on the shoulders and back.", Tristram's Natural History.
Then came a wonder of natural history, a pygarg, said to be from Russia.