Central capsule subspherical, a little longer than broad. Podoconus about two-thirds as long as the capsule, with trifid porochora, which is composed of three equal circular lobes. Nucleus spherical. Numerous oil-globules in the endoplasm. The calymma includes numerous xanthellæ and brown pigment around the mouth. _Dimensions._--Length of the central capsule 0.06, breadth 0.05; nucleus 0.03. _Habitat._--Mediterranean, Messina (R. Hertwig), surface. {898}Genus 383. _Nassella_,[2] nov. gen. _Definition._--#Nassellida# with foamy calymma, containing numerous large extracapsular alveoles. The genus _Nassella_ differs from the preceding _Cystidium_, its probable ancestral form, in the development of numerous large alveoles in the extracapsular calymma, and therefore exhibits the same relation to it that _Thalassicolla_ bears to _Actissa_ among the SPUMELLARIA. The foamy calymma is very voluminous, and includes numerous symbiotic xanthellæ. 1. _Nassella thalassicolla_, n. sp. Central capsule spherical. Podoconus with simple circular porochora, half as long as the capsule. Nucleus spherical. Numerous oil-globules in the endoplasm. Calymma spherical, without pigment, with numerous xanthellæ and large alveoles. _Dimensions._--Diameter of the central capsule 0.12, nucleus 0.04, calymma 0.6. _Habitat._--South Pacific, Station 300 (off Juan Fernandez), surface. 2. _Nassella nassiterna_, n. sp. Central capsule ovate. Podoconus two-thirds as long as the capsule, trifid, with three equal circular lobes (as in _Cystidium inerme_). Nucleus ovate. Three equal large oil-globules in the endoplasm, corresponding to the three lobes of the porochora. Calymma ovate, in the upper half much more voluminous than in the lower, including numerous large alveoli and xanthellæ, and around the mouth masses of black pigment. _Dimensions._--Diameter of the central capsule 0.1, nucleus 0.03, calymma 0.8. _Habitat._--Indian Ocean, Madagascar (Rabbe), surface. ---- Suborder II. PLECTOIDEA, Haeckel. _Plectoidea_ vel _Plectida_, Haeckel, 1881, Prodromus, p. 423. _Plagiacanthida_ (_sensu ampliori_), R. Hertwig, 1879, Organismus d. Radiol., p. 72. _Definition._--NASSELLARIA with a rudimentary, originally tripodal skeleton, composed of radial spines, arising from one common central point or central rod; the spines are simple or branched, and the branches may form by concrescence of their meeting ends a loose wickerwork, but never a complete lattice-shell. Never a ring in the skeleton.