hippotragusnasomaculatus

from The Collaborative International Dictionary of English v.0.48

Addax \Ad"dax\, n. [Native name.] (Zool.)
   One of the largest African antelopes
   ({Hippotragusnasomaculatus} or {Oryx nasomaculatus}).
   [1913 Webster]

   Note: It is now believed to be the {Strepsiceros} (twisted
         horn) of the ancients. By some it is thought to be the
         pygarg of the Bible.
         [1913 Webster]