proostracum
Pro*ös"tra*cum, n.; pl. Proöstraca. Etym: [NL., fr. Gr. (Zoöl.) Defn: The anterior prolongation of the guard of the phragmocone of belemnites and allied fossil cephalopods, whether horny or calcareous. See Illust. of Phragmocone.
Pro*ös"tra*cum, n.; pl. Proöstraca. Etym: [NL., fr. Gr. (Zoöl.) Defn: The anterior prolongation of the guard of the phragmocone of belemnites and allied fossil cephalopods, whether horny or calcareous. See Illust. of Phragmocone.