The Trocholitidae are Tarphycerida with whorls in close contact as with the Tarphyceratidae, but in which the siphuncle, similar in structure, becomes dorsal.

In Graftonoceras and Jasperoceras the venter is rounded and continues smoothly through the flanks to a broad dorsum which in each is moderately impressed.

Whorls in Trocholites have a wide cross section and low profile, in Wichitoceras they are laterally compressed resulting in a high-profile.

Arkoceras, Trocholitoceras, and Wichitoceras are limited to the upper Lower Ordovician, along with the enigmatic Beekmanoceras which may or may not belong.

Hardmanoceras which is strongly ribbed may be the ancestor of the Ophidioceratidae of the Upper Silurian Genera assigned to the Trocholitidae[1] are found in three principal realms: North America, Australia, and Northern Europe (Balto-Scandia).