The addax, also known as the white antelope and the screwhorn antelope, is an antelope native to the Sahara. The only member of the genus Addax, it was first described scientifically by Henri de Blainville in 1816. As suggested by its alternative name, the addax has spiral horns that are 55 to 80 cm long in females and 70 to 85 cm in males. In the winter, its coat is greyish-brown with white hindquarters and legs, and long, brown hair on the head, neck, and shoulders; in the summer, the coat turns almost completely white or sandy blonde. Males stand from 105 to 115 cm at the shoulder, with females at 95 to 110 cm. They are sexually dimorphic, as the females are generally smaller than the males.