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,
Male/Female (Borofsky) Male/Female (Borofsky) "Male/Female" is a tall hollow stainless steel sculpture by Jonathan Borofsky standing at the entrance to Pennsylvania Station in Baltimore, Maryland. It depicts intersecting colossal male and female forms with pulsing light-emitting diode light. Male Female is a work of public art commissioned by the Municipal Art Society of Baltimore City, a private non-profit organization founded in 1899 "to provide sculptural and pictoral decoration and ornaments for the public buildings, streets and open spaces in the City of Baltimore, and to help generally beautify the City." (from the original charter) Male Female was created by artist Jonathan Borofksy