Onager

[I]f the czigithai is not the ſame with the zebra, it may be the Aſiatic animal called onager or wild aſs. The onager ſhould not be confounded with the zebra; but I am uncertain whether the ſame remark is applicable to the onager and czigithai; for, from comparing the relations of travellers, it appears, that there are different kinds of wild aſſes, of which the onager is the moſt remarkable. […] The ſwiftneſs of the onager is mentioned by travellers, who remark, that he runs with ſuch rapidity as to eſcape the hunters, though mounted on horſes; […]

The onager, or wild aſs, is ſeen in ſtill greater abundance than the wild horſe; and the peculiarities of its kind are more diſtinctly marked than in thoſe of the tame one.

One of the onagers, however, having hurt its leg, could not be harnessed at present, and a few days' rest was necessary.

The onager, meaning "wild ass," derived its name from its powerful recoil, or kick, upon discharge; […] In addition, although Josephus described an onager in action hurling a 100-pound stone over 400 yards, most onagri achieved a shorter range than the ballista, thus exposing their crews to enemy archers.