We divide the immense legion of Nassellaria into two large orders, the Plectellaria without complete lattice-shell, and the Cyrtellaria with a complete lattice-shell or a "cephalis," including the central capsule; the latter, of course, have arisen from the former. The Plectellaria comprise three different suborders, the Nassoidea (without skeleton), the Plectoidea (with a tripodal skeleton, without ring), and the Stephoidea (with a primary sagittal ring, with or without tripod). The Cyrtellaria again also comprise three different suborders, the Spyroidea (with bilocular cephalis and a sagittal constriction), the Botryodea (with multilocular and lobate cephalis, exhibiting two or more constrictions and three or more lobes), and the Cyrtoidea (with simple, unilocular cephalis, without constriction).
Synopsis of the Orders and Suborders of Nassellaria.
| I. Order PLECTELLARIA.
Nassellaria without complete lattice-shell. |
No skeleton, | 1. Nassoidea. | |
| Skeleton with a basal tripod, without ring, | 2. Plectoidea. | ||
| Skeleton with a sagittal ring (usually without tripod), | 3. Stephoidea. | ||
| II. Order CYRTELLARIA.
Nassellaria with a complete lattice-shell. |
Cephalis bilocular, with a sagittal constriction, | 4. Spyroidea. | |
| Cephalis multilocular, with two or more constrictions and lobes, | 5. Botryodea. | ||
| Cephalis simple, without constriction and lobes, | 6. Cyrtoidea. |
Order V. PLECTELLARIA, Haeckel, 1883.
Definition.—Nassellaria without complete lattice-shell, usually with an incomplete skeleton, formed of a ring, a tripod, or an irregular framework.
Suborder I. NASSOIDEA, Haeckel.
Definition.—Nassellaria without skeleton. Single family Nassellida.
