Order xi. Nassoidea.—Skeleton absent. (Family 45.)
Order xii. Plectoidea.—Skeleton of a single branching spicule, the branches sometimes reticulate, but never forming a latticed shell or a sagittal ring. (Families 46-47.)
Order xiii. Stephoidea.—Skeleton with a sagittal ring continuous with the branched spicule, and sometimes other rings or branches. (Families 48-51.) Lithocercus Théel (Fig. 26, A).
Order xiv. Spyroidea.—Skeleton with a latticed shell developed around the sagittal ring (cephalis), and constricted in the sagittal plane, with a lower chamber (thorax) sometimes added. (Families 52-55.)
Order xv. Botryoidea.—As in Spyroidea, but with the cephalis 3-4 lobed; lower chambers, one or several successively formed. (Families 56-58.)
Order xvi. Cyrtoidea.—Shell as in the preceding orders, but without lobing or constrictions. (Families 59-70.) Theoconus Haeck. (Fig. 25, B).
D. Phaeodaria.
Order xvii. Phaeocystina.—Skeleton 0 or of distinct spicules; capsule centric. (Families 71-73.) Aulactinium Haeck. (Fig. 26, B).
Order xviii. Phaeosphaeria.—Skeleton a simple or latticed sphere, with no oral opening (pylome); capsule central. (Families 74-77.)
Order xix. Phaeogromia.—Skeleton a simple latticed shell with a pylome at one end of the principal axis; capsule excentric, sub-apical. (Families 78-82.) Pharyngella Haeck.; Tuscarora Murr.; Haeckeliana Murr. (Fig. 28).