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,
Female and Male Herm (sculpture set) the eastern side of the path and "Male Herm" on the western. They have remained in approximately the same place since (with the exception of some time in storage during the 1992 Formal Garden renovation). The marble sculptures are monitored, cleaned, and treated regularly by the IMA art conservation staff. Both sculptures are considered structurally sound and stable as of 2011. Female and Male Herm (sculpture set) Female Herm and Male Herm are a set of two neoclassical marble herms in the outdoor sculpture collection of the historic Oldfields estate, located on the campus of the Indianapolis Museum of Art