The Plectoceratidae as recently redefined contain three genera so closely allied that their distinction may be considered dubious. Alaskoceras, added to the family by Miller and Kummel, is of uncertain position. Its gross features do not warrant its distinction from Plectoceras. Its siphuncle however, indicate a relationship with the Canadian Tarphyceratidae instead of the Ordovician Plectoceratidae.