Harrisoceras Flower, 1939 † (original description)
Harrisoceras ignotum Flower, 1939 † (original description)
Harrisoceras laurelense Flower, 1939 † (original description)
Harrisoceras monocameratum Flower, 1939 † (original description)
Harrisoceras obstructum (F. H. Newell, 1888) † (basis of record)
Harrisoceras orthoceroides Flower, 1939 † (original description)
Harrisoceras rectum (Worthen, 1875) † (basis of record)
Harrisoceras reevesi Flower, 1939 † (original description)
Orthoceras obstructum F. H. Newell, 1888 † accepted as Harrisoceras obstructum (F. H. Newell, 1888) † (new combination reference)
Orthoceras rectum Worthen, 1875 † accepted as Harrisoceras rectum (Worthen, 1875) † (new combination reference)

Illinois for Harrisoceras orthoceroides Flower, 1939 † 
Indiana for Harrisoceras ignotum Flower, 1939 † 
Indiana for Harrisoceras laurelense Flower, 1939 † 
Indiana for Harrisoceras monocameratum Flower, 1939 † 
Indiana for Harrisoceras reevesi Flower, 1939 †