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Parryoceras is a cyrtogomphoceratid similar to Strandoceras but with broadly expanded siphuncle segments and a nearly straight ventral line. The mature shell is thickened on the inside just behind the aperture resulting in a constriction in the internal mold at the adoral end.
Parryoceras comes from the middle and upper Ordovician of arctic Canada and Norway.
References
Parryoceras Wikipedia(Text) CC BY-SA