[Class] Polycystinea Ehrenberg, 1838 - polycystines see Superclass Polycystinia Ehrenberg, 1838 Order Nassellaria Ehrenberg, 1875 see Class Nassellaria Ehrenberg, 1847 Family Plagiacanthidae Hertwig, 1879 Genus Arachnocorallium Haeckel, 1887 1 Arachnocorallium calvata Petrushevskaya, 1971