Source : Webster's Revised Unabridged Dictionary (1913)

Sirenia \Si*re"ni*a\, n. pl. [NL.] (Zo["o]l.)
   An order of large aquatic herbivorous mammals, including the
   manatee, dugong, rytina, and several fossil genera.

   Note: The hind limbs are either rudimentary or wanting, and
         the front ones are changed to paddles. They have horny
         plates on the front part of the jaws, and usually
         flat-crowned molar teeth. The stomach is complex and
         the intestine long, as in other herbivorous mammals.
         See {Cetacea}
   (b) .

Source : WordNet®

Sirenia
     n : manatees; dugongs; Stellar's sea cow [syn: {order Sirenia}]