Protocyathus FORD, 1878
Specimen-type: Protocyathus rarus holotype, FORD, 1878, fig. 1a-b
Systematics:
Order: AJACICYATHIDA R. Bedford& J. Bedford, 1939
Suborder: AJACICYATHINA R. Bedford& J. Bedford, 1939
Superfamily: ETHMOPHYLLOIDEA Okulitch, 1937
Family: KIJACYATHIDAE Zhuravleva, 1964