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

The other animal which belongs to the horse family is zebra.

The zebra is also apart of the horse family... I HOPE THAT ANSWERS YOUR QUESTION.

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.