Ctenoceras Noetling, 1884

Diagnosis. Slightly cyrtoconic, slightly compressed shell,with prominent sinuous, irregularly spaced annulation,growth lines, and fine longitudinal costules. Body chamberwith two impressions at the concave parts of the flanks andone at the convex side. Siphuncle subcentral toward the con-vex side of the shell, nearly tubular with orthochoanitic sep-tal necks. No endosiphuncular and cameral deposits known.