Which Other Animal Belongs To The Horse Family Apart From The Pony, Mule And Donkey?

There is at least one more but I don't know the name right off the top of my head.  I think it is a cross between a zebra and a wild burro (donkey, jackass, whatever you call it).  The pictures I have seen show it to be usually dun colored to darker brown, I think it has the dark stripe down the back too, and the legs are striped from the hoof to about half-way up.  Anyone else remember this critter?  Let me know if the name comes up.  I've seen them in person too, at zoos and at a carnival once.