What is "clydonautilaceae"

The Clydonautilaceae is a superfamily within the nautiloid order Nautilida characterized by smooth, generally globular, shells (Kummel 1964) with nearly straight sutures, in early forms but developing highly differentiated sutures in some later forms. Where known, the siphuncle tends to be central to subcentral.

The Clydonautilaceae, name based on Hyatt's Clydonautilidae of 1900, is more or less the Liroceratina of Shimansky 1962.