sirenia

n. pl. [ NL. ] (Zool.) An order of large aquatic herbivorous mammals, including the manatee, dugong, rytina, and several fossil genera. [ 1913 Webster ]

☞ 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). [ 1913 Webster ]