[Class] Polycystinea Ehrenberg, 1838 - polycystines see Superclass Polycystinia Ehrenberg, 1838 Order Nassellaria Ehrenberg, 1875 see Class Nassellaria Ehrenberg, 1847 Family Plagiacanthidae Hertwig, 1879 Genus †Tripilidium Haeckel, 1881 †Tripilidium clavipes Clark & Campbell, 1942 †Tripilidium clavipes advena Clark & Campbell, 1945