Proostracum
Pronunciation : Pro*?s"tra*cum
Part of Speech : n.;
Etymology : [NL., fr. Gr. (Zo?l.)
Definition : Defn: The anterior prolongation of the guard of the phragmocone of belemnites and allied fossil cephalopods, whether horny or calcareous. See Illust. of Phragmocone.
pl. Pro?straca.
Source : Webster's Unabridged Dictionary, 1913