Proöstracum

Definitions

  • Webster's Revised Unabridged Dictionary
    • n Proöstracum (Zoöl) The anterior prolongation of the guard of the phragmocone of belemnites and allied fossil cephalopods, whether horny or calcareous. See Illust. of Phragmocone.
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Century Dictionary and Cyclopedia
    • n proostracum The broad and projecting lamella of the thick covering of the phragmacone of a cephalopod, extending beyond the base of the phragmacone, and being a continuation of the wall of the most anterior chamber of the shell; the foremost part of the guard or rostrum of a fossil cephalopod of the belemnite group. It is variously shaped, usually lamellate, and with the rostrum represents the pen of the squids. See cuts under belemnite, Belemnitidæ, and calamary.
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Chambers's Twentieth Century Dictionary
    • n Proostracum prō-os′tra-kum the forward continuation of the guard or rostrum in the Belemnites.
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Etymology

Webster's Revised Unabridged Dictionary
NL., fr. Gr. before + shell of a testacean
Chambers's Twentieth Century Dictionary
Gr. pro, before, ostrakon, shell.