The Lituitidae are a family of evolved tarphycerids characterized by a long orthoconic section that follows a coiled juvenile portion at the apex, along with a generally tubular siphuncle, which like that of the barrandeocerids is composed of thin connecting rings.

Other taxonomies, e.g. Dzik (1981)[3] include the Lituitidae in the Orthocerida partly on the basis of the subcentral siphuncle and thin connecting rings, on the misconception that Rhynchorthoceras is ancestral.

[2] The coiled juvenile portions of the Lituitidae are characterized by a deep hyponomic sinus and lateral salients at the aperture, indicating a high degree of mobility.

The orthoconic adult portions are characterized by a shallow hyponomic sinus as in Ancistroceras indicating a more passive lifestyle, or a complex aperture with lappets as in Litoceras.

[4] Nowhere is there any direct evidence of orthoconic forms developing coiling at their apexes[5] nor does any obvious advantage exist for them to have done so.