Artharia Billings, 1872

Diagnosis, emended. Dumb-bell shaped trace preserved on lower surfaces as positive casts, composed of a shallower stem con- necting two wider and more deeply im- pressed terminations. Terminations com- monly both hemispherical, but heart, dogbone or arrowhead shapes and in various combi- nations also possible. Terminations do not extend vertically upward into overlying sed- iment. Thus, vertical tubes and spreite are absent.