_The Nucleus_ of the SPUMELLARIA is originally constantly _central_, placed quite in the centre of the concentric capsule, and it retains this central position in all Monocyttaria or solitary Peripylea; whereas in the Polycyttaria--in consequence of its early division--its place is commonly taken by a central oil-globule. Whilst the numerous nuclei of the latter are very small, the single nucleus of the former is comparatively large, extremely large (more than a millimeter in diameter) in some gigantic #Collodaria#. _The Endoplasm_ or the intracapsular sarcode exhibits in the greater number of SPUMELLARIA a more or less distinct radial striation. It encloses a great variety of different parts; vacuoles, oil-globules, pigment-granules, crystals, &c. _The Membrane_ of the capsule in all SPUMELLARIA is simple (never double as in the _Phæodaria_) and everywhere equally perforated by innumerable small pores; in the thick, double-edged membrane of many large #Collodaria# these pores appear (in the optical section of the capsule-wall) as distinct fine radial canals, very densely and regularly disposed. _The Central Capsule_ in the SPUMELLARIA is originally a _geometrical sphere_, and this simple globular form is preserved in all #Sphæroidea#, and in the greatest part of #Colloidea# and #Beloidea#. By prolongation of one axis the form becomes _ellipsoidal_ (or even cylindrical) in the #Prunoidea#, and in some few forms of #Colloidea#. By shortening of one axis it becomes _lenticular_ (or even discoidal) in the _Discoidea_, and in some few forms of #Colloidea#. By unequal growth in three different axes, perpendicular one to another, the capsule becomes _lentelliptical_ in all #Larcoidea#. Very rarely the capsule assumes in the SPUMELLARIA a polyhedral or irregular (sometimes even amoeboid) form, only in a few #Colloidea#. _The Calymma_, or the jelly-veil including the central capsule, is very voluminous in many SPUMELLARIA of gigantic size, mainly in the large #Colloidea#, and in all Polycyttaria or social Radiolaria. It includes here a considerable number of large vacuoles or "alveoli." The calymma never exhibits in this legion the dark voluminous phæodium, possessed by all PHÆODARIA. _Xanthellæ_ or "zooxanthellæ" are numerous in the calymma of most SPUMELLARIA, but by no means constant; they are very variable in number and size. _The Matrix_, placed between the calymma and central capsule, is, in the majority of the SPUMELLARIA, a rather thick layer of granular exoplasm. _The Pseudopodia_ arising from it are very numerous, equally disposed over the whole {9}surface, and are in general rather fluid, exhibiting a considerable tendency to ramify, anastomose, and form networks. The movement of granules is commonly lively. In the Polycyttaria all capsules of one colony or "coenobium" are connected by the dense variable network of anastomosing pseudopodia. _Synopsis of the Orders and Suborders of_ SPUMELLARIA.