Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Equus (comics) not being paid by him. Nox reminds him that Equus is there to aid him, but Equus brushes Nox aside, and attacks Superman. Superman is less forgiving in this rematch, using his X-ray and microscopic visions to learn much about Equus' enhancements, and physically disabling much of their exterior components. Equus escapes by activating the weapon, causing not only himself to vanish, but another 300,000 other people from across the planet. Superman subsequently learns that Equus has been working for a mysterious mustached man named Mr. Orr, who explains to Superman that Orr's employer's financed Nox's war, and loaned Equus