Family Leiopathidae Haeckel, 1896

Diagnosis. “Polyps with six primary and six secondary mesenteries. Primary (pm) and secondary mesenteries (sm) complete, attached to both inner wall of oral cone and actinopharynx. Secondary mesenteries located between transverse primary mesenteries (tpm) and sagittal primary mesenteries (spm); two on one side and four on opposite side of transverse axis, with one-half of each complement occurring on each side of sagittal axis; clockwise pattern described by sequence tpm-sm-spm-spm-sm-tpm-sm-sm-spm-spm-sm-sm. New polyps developing from coenenchymal surface between older polyps, as well as at distal end of branchlets” (Opresko, 1998).