Aplacophora :: Aplacophora (n. pl.) A division of Amphineura in which the body is naked or covered with slender spines or setae, but is without shelly plates..
Placodermi :: Placodermi (n. pl.) 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..
Placoganoid :: Placoganoid (a.) Pertaining to the Placoganoidei.
Placoganoidei :: Placoganoidei (n. pl.) A division of ganoid fishes including those that have large external bony plates and a cartilaginous skeleton.
Placoid :: Placoid (a.) Platelike; having irregular, platelike, bony scales, often bearing spines; pertaining to the placoids..
Placoid :: Placoid (n.) Any fish having placoid scales, as the sharks..
Placophora :: Placophora (n. pl.) A division of gastropod Mollusca, including the chitons. The back is covered by eight shelly plates. Called also Polyplacophora. See Illust. under Chiton, and Isopleura..