Bactroceratidae King & Evans, 2019

Kröger, Björn & Pohle, Alexander, 2021, Early-Middle Ordovician cephalopods from Ny Friesland, Spitsbergen - a pelagic fauna with Laurentian affinities, European Journal of Taxonomy 783 (1), pp. 1-102 : 33-34

Family Bactroceratidae King & Evans, 2019

Emended diagnosis

Slender orthoconic to weakly cyrtoconic shells with usually faint ornamentation consisting of transverse growth lines or low striae; siphuncle marginal, narrow; dorsomyarian muscle scars; septal necks orthochoanitic to hemichoanitic, connecting rings thin and homogeneous, slightly expanded into chambers; embryonic shell moderately large, subspherical and with constriction; cicatrix absent (slightly modified from King & Evans 2019).

Remarks

The diagnosis of the Bactroceratidae King & Evans, 2019 is emended with respect to the statement of a presence or absence of endosiphuncular and cameral deposits, which follows a discussion of the type genus of this family (see below). A statement about the presence or absence of deposits is removed from the diagnosis herein.