Plac"o*derm (?), n. [Gr. &?;, &?;, tablet + &?; skin.] (Paleon.) One of
the Placodermi.
Plac`o*der"mal (?), a. (Paleon.) Of or pertaining to the placoderms;
like the placoderms.
||Plac`o*der"ma*ta (?), n. pl. [NL.] (Paleon.) Same as Placodermi.
||Plac`o*der"mi (?), n. pl. [NL., fr. Gr. &?;, &?;, a tablet + &?;
||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.
Plac`o*ga"noid (?), a. (Zoˆl.) Pertaining to the Placoganoidei.
||Plac`o*ga*noi"de*i (?), n. pl. [NL., fr. Gr. &?;, &?;, a tablet + NL.
||ganoidei. See Ganoidei.] (Zoˆl.) A division of ganoid fishes
||including those that have large external bony plates and a
||cartilaginous skeleton.
Plac"oid (?), a. [Gr. &?;, &?;, a tablet + -oid.] (Zoˆl.) Platelike;
having irregular, platelike, bony scales, often bearing spines;
pertaining to the placoids.
Plac"oid, n. (Zoˆl.) (a) Any fish having placoid scales, as the sharks.
(b) One of the Placoides.
||Pla*coi"des (?), n. pl. [NL.] (Zoˆl.) A group of fishes including the
||sharks and rays; the Elasmobranchii; -- called also Placoidei.
Pla*coid"i*an (?), n. (Zoˆl.) One of the placoids.
||Pla*coph"o*ra (?), n. pl. [NL., from Gr. &?;, &?;, tablet + &?; to
||bear.] (Zoˆl.) 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.
||Pla"ga (?), n.; pl. PlagÊ (#). [L. plga a blow, a welt, a stripe.]
||(Zoˆl.) A stripe of color.
Pla"gal (?), a. [F., from Gr. &?; sidewise, slanting.] (Mus.) Having a
scale running from the dominant to its octave; -- said of certain old
church modes or tunes, as opposed to those called authentic, which ran
from the tonic to its octave.
Plagal cadence, a cadence in which the final chord on the tonic is
preceded by the chord on the subdominant.
Pla"gate (?), a. (Zoˆl.) Having plagÊ, or irregular enlongated color
spots.
Plage (?), n. [F., fr. L. plaga.] A region; country. [Obs.] "The plages
of the north." Chaucer.
Pla"gia*rism (?), n. [Cf. F. plagiarisme.] 1. The act or practice of
plagiarizing.