The Collaborative International Dictionary of English v.0.48:

Struthio \Stru"thi*o\, n.; pl. Struthiones. [L., an ostrich,
   fr. Gr. ?.] (Zool.)
   A genus of birds including the African ostriches.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Struthiones \Stru`thi*o"nes\, n. pl. [NL. See Struthio.]
   (Zool.)
   (a) A division, or order, of birds, including only the
       African ostriches.
   (b) In a wider sense, an extensive group of birds including
       the ostriches, cassowaries, emus, moas, and allied birds
       incapable of flight. In this sense it is equivalent to
       Ratitae, or Dromaeognathae.
       [1913 Webster]