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,
What Is and What Should Never Be (Supernatural) What Is and What Should Never Be (Supernatural) "What Is and What Should Never Be" is the twentieth episode of the paranormal drama television series "Supernatural"s second season. It was first broadcast on May 3, 2007 on The CW. The narrative follows series protagonist Dean Winchester (Jensen Ackles) who finds himself in an alternate reality after a confrontation with a djinn . The creature appears to have fulfilled Dean's greatest wish: that his mother had not been killed when he was a child. Dean is happy in the new world until it becomes apparent that his previous work as a