|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|J. R. Laurie 1986||Organisms with densely tamellar phosphatic sclerites, all variably pyramidal to conical with prominent apices; strong, regular, concentric ribbing with superimposed finely reticulate micro-ornament. Sclerites belong to three forms. They are:
Form A. Bilaterally symmetrical, subrectangular or ovate in section with curvature in plane of symmetry. Form B. Asymmetrical, ovate to subquadrate or rectangular in section with curvature absent to moderate, torsion slight to strong, found in dextral and sinistral forms.
Form C. Asymmetrical, subtriangular to crescentic in section, curvature slight to strong, torsion absent to moderate, found in dextral and sinistral forms.