Mules

a Mule is a hybrid, rather than a species
a mule is the offspring of a male donkey (jack) and a female horse
mules are usually sterile, but there have been a couple of rare cases in which a mare mule produced a foal
mules have 63 chromosomes; horses have 64 and donkeys have 62
a hinny is the offspring of a male horse and a female donkey (jennet)
a female mule is called a mare or molly mules
a male mule is called a horse or john mule
in 1787 the Marquis de Lafayette gave George Washington a donkey jack for mule production; named Knight of Malta, he was the first notable donkey to be imported
Royal Gift, given by the King of Spain, was the second donkey of quality to be imported
the U.S. army used mules extensively up to 1957
mules are now popular pack and trail riding animals, and are also shown in many disciplines
mules may be any color or conformation type, as inherited from the dam
American Donkey and Mule Society

Donkeys