The Collaborative International Dictionary of English v.0.48:

Rytina \Ryt"i*na\ (r[i^]t"[i^]*n[.a]), n. [NL., fr. Gr. "ryti`s
   a wrinkle.] (Zool.)
   A genus of large edentulous sirenians, allied to the dugong
   and manatee, including but one species (Rytina Stelleri);
   -- called also Steller's sea cow, stellerine and
   steller. [Written also Rhytina.]
   [1913 Webster]

   Note: It is now extinct, but was formerly abundant at
         Bering's Island, near Bering's Straits. It was
         twenty-five feet or more in length, with a thick,
         blackish, naked skin. The last were killed in 1768 for
         their oil and flesh.
         [1913 Webster]
         [1913 Webster]