Placodermi

from WordNet (r) 3.0 (2006)

Placodermi
    n 1: extinct group of bony-plated fishes with primitive jaws
         [syn: {Placodermi}, {class Placodermi}]

from The Collaborative International Dictionary of English v.0.48

Placodermi \Plac`o*der"mi\, n. pl. [NL., fr. Gr. pla`x, plako`s,
   a tablet + de`rma skin.] (Paleon.)
   An extinct group of fishes, supposed to be ganoids. The body
   and head were covered with large bony plates. See Illust.
   under {Pterichthys}, and {Coccosteus}.
   [1913 Webster]