Proostraca

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Proostracum \Pro*["o]s"tra*cum\, n.; pl. {Proostraca}. [NL., fr.
     Gr. ? before + ? shell of a testacean.] (Zool.)
     The anterior prolongation of the guard of the phragmocone of
     belemnites and allied fossil cephalopods, whether horny or
     calcareous. See Illust. of {Phragmocone}.
     [1913 Webster]