Trocholitoceras Hyatt, 1894

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 : 69

Genus Trocholitoceras Hyatt, 1894

Type species

Trocholitoceras walcotti Hyatt, 1894 , from the Fort Cassin Limestone (late Floian Stage), Fort Cassin, Addison County, Vermont, USA; by original designation.

Diagnosis

Moderately large, subdiscoidal, involute conchs with a ca 180° long body chamber; umbilical perforation very small; ornamented with prominent, partly fasciculate growth lines and low ribs which form a deep rounded ventral sinus; sutures directly transverse and nearly straight except on dorsal side where they form a shallow lobe; siphuncle small, subcentral during early adolescence, dorsal or nearly so at maturity (from Ulrich et al. 1942: 80).