Spumellaria

“ Such indifferently stable bodies are found among the Spumellaria in many Collodaria and Sphæroidea, as well as in the Astrolophida among the Acantharia. On the contrary they are entirely wanting among the Nassellaria and Phæodaria, since their central capsule constantly presents a main axis with a differentiated basal pole, and determines the position of stable equilibrium. ”

“ The radial spines of the Spumellaria are never united in the centre of the body, but arise separately from the surface of the primary central lattice-shell (medullary shell) , more rarely from one of the secondary (cortical) shells, which enclose it. Their form is originally three-edged (sometimes pyramidal, sometimes prismatic) ; the cause of this is to be found in their origin from the nodal points of the lattice-shell, whose meshes are primitively hexagonal; hence three trabeculæ unite in each nodal point, and are produced into three edges of the spine. ”

“ The Monocyttaria (or the Spumellaria solitaria) live isolated as single cells—like {8}all other Radiolaria—and are never aggregated in colonies; the calymma includes one single central capsule, and this again one central nucleus, which does not become divided until full maturity.
The Polycyttaria on the contrary (or the Spumellaria socialia) live aggregated in large colonies; the calymma includes a variable number of associated central capsules and each of these commonly one central oil-globule, whilst the original simple nucleus commonly becomes very early divided into numerous small nuclei. ”

“ In many Spumellaria, and particularly in the Polycyttaria, an albuminous substratum may be recognised in them, which is sometimes disposed in layers, and after extraction of the fat presents the appearance of a laminated sphere. The physiological significance of the oil-globules is twofold; in the first place they tend to diminish the specific gravity of the organism; in the second they may be utilised as a reserve store of nutriment. In the latter respect they are of special importance in the process of spore-formation, each flagellate spore usually containing a fat-granule. ”

“ 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 Ground-Forms of the Spumellaria.—The Spumellaria, being the oldest and most primitive Radiolaria, have for the most part either indifferent or multistable equilibrium; e.g., all Colloidea and Beloidea which have a spherical central capsule, and also most Sphæroidea. Among these primitive Centrostigma true spheres and endospherical polyhedra are represented in the utmost variety, and the regular polyhedra in particular. By the development of a vertical main axis these Centrostigma have also given rise to very numerous Centraxonia, which are usually isopolar, very rarely allopolar. ”

“ The Ectolithia, with a completely extracapsular skeleton, include all Nassellaria and Phæodaria, as well as a great part of the Spumellaria (all Collodaria and the most archaic forms of Sphærellaria) ; the Entolithia, on the other hand, in which the skeleton lies partly within, partly without the central capsule, include all Acantharia and the majority of the Spumellaria (most Sphærellaria, see note B) . ”

“ Although the monophyletic derivation of all Sphærellaria from Cenosphæra is exceedingly probable, the possibility of a polyphyletic origin for the group is by no means excluded. For even in the skeletonless primitive genus of all the Spumellaria, Actissa (as well as in the social Collozoum) , there are found, in addition to the usual spherical types, other species (or subgenera, p. 12) whose central capsule is not spherical but a modification of the sphere ”

“ Also in the latest system of Ehrenberg (1875, loc. cit., p. 157) his Haliommatina are a confused conglomeration of different Spumellaria (Sphæroidea, Discoidea, and Prunoidea) .
The section Sphæroidea is the largest division of Sphærellaria, comprising not less than one hundred and seven genera and six hundred and fifty species. This enormous number (easily to be augmented by further investigations) requires a careful disposition in different families and subfamilies. For this disposition two different principles only can be employed: firstly, the number and disposition of the radial spines ”

“ In the Polycyttaria (or social Spumellaria, i.e., the three families Collozoida, Sphærozoida, and Collosphærida) , the cause of the adaptation lies most probably in the formation of the colony itself, for all these three families are so closely related to three corresponding families of serotinous, monozootic Radiolaria (Thalassicollida, Thalassosphærida, Ethmosphærida) , that certain species of the latter are hardly to be distinguished from isolated individuals of the former. ”

“ The manifold delicate appendages (spines, bristles, feet, wings, &c.) which are so richly developed in the living Spumellaria and Nassellaria, and are also well shown in the Tertiary species, are entirely wanting in the majority of the Jurassic Polycystina. The Sphæroidea and Prunoidea are all simple spherical or ellipsoidal lattice-shells (Monosphærida) ; concentric lattice-shells (Polysphærida) are entirely wanting. The Cyrtoidea are, for the most part, devoid of radial processes or basal feet (Eradiata) ”

“ The suborder Sphæroidea, the first and most important of the four of the Sphærellaria, comprises those Spumellaria in which the original geometrical {51}spherical form is quite constantly preserved in the central capsule, and commonly also in the fenestrated shell enveloping the latter, although in many forms the sphere is more or less modified; very frequently it is an "endospherical polyhedron," i.e., a polyhedron all the angles (or the nodes of the network) of which lie upon the surface of a geometrical sphere; more rarely the spherical form is more or less modified and irregular. ”

“ In the Cyrtellaria (or Nassellaria with a complete lattice-shell, Pls. 51-80) , on the other hand, the lattice-work is sometimes regular, sometimes irregular, being often very different in the different joints of a segmented shell (Pl. 72) ; a great part of it arises independently of the two chief morphological elements, and develops according to laws similar to those which regulate the dictyosis of the Spumellaria. ”

“ 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 "cœnobium" are connected by the dense variable network of anastomosing pseudopodia. ”

“ Whilst in the Phæodaria, Acantharia, and Nassellaria, at most two concentric shells are formed, in many Spumellaria their number increases continuously with additional growth; in many Sphærellaria it rises to four, eight, or even more, as well as in many Discoidea (if the concentric, peripherally disposed rings of chambers be regarded as incomplete flattened shells) . In these cases either only the innermost primary lattice-shell is to be styled "medullary shell," or at most the two innermost (inner and outer medullary shells) , all the others being cortical. ”

“ At that time I could not separate them sufficiently from some Acantharia and Phæodaria, which have a similar spherical lattice-shell.
As the number of different genera and species in the Sphæroidea is much greater than in all other sections of Spumellaria, many forms were already described by former authors. In the oldest system of Ehrenberg (1847, loc. cit., p. 53) they represent one part of his Haliommatina (with four genera, Haliomma, Chilomma, Stylosphæra, Spongosphæra) . Most species, however, of these genera are Discoidea. ”

“ The first order, Collodaria, have either no skeleton whatever (Colloidea, p. 10, Pls. 1, 3) , or their skeleton is Beloid, a loose extracapsular envelope of spicules, consisting of numerous unconnected portions; the separate parts are usually disposed tangentially, either as simple or compound siliceous spicules (Beloidea, p. 28, Pls. 2, 4) . The second order of Spumellaria, on the other hand (Sphærellaria, p. 49) , develops a siliceous lattice-shell which consists of a single piece, and is remarkable for the extraordinary variety of its forms (pp. 50-715, Pls. 5-50) . ”

“ The Central Capsule of the Spongurida is either ellipsoidal or cylindrical. Only in Spongellipsis it lies freely in the internal cavity of the spongy shell. In all other genera it is perforated by a part of the skeleton; in the Spongodruppida it contains the simple or double medullary shell, and the radial beams which perforate its membrane and connect the latter with the external spongy cortical shell. In Spongurus and the allied genera (Spongocore, Spongoprunum) the whole central capsule is filled with a spongy framework which also envelops its surface. ”

“ Definition.—Spongurida with an ellipsoidal or cylindrical spongy shell, containing an internal cavity, without a latticed medullary shell. Polar spines absent.
The genus Spongellipsis embraces those very simple Spongurida in which the ellipsoidal central capsule is enclosed in a spongy cortical shell of the same form. It corresponds, therefore, to Plegmosphæra among the Sphæroidea, to Plegmodiscus among the Discoidea, and to Spongolarcus among the Larcoidea. In some species the ellipsoidal form is prolonged and passes into a cylindrical one. ”

“ Many of these Spongosphærida are very common, and of considerable size.
The Collosphærida form a peculiar separate group of Sphæroidea, distinguished from all others by their social life or aggregation in colonies (cœnobia) . They represent the only group of Sphærellaria in which this association of numerous individual capsules or cells is realised. The shell is almost constantly simple, without regularly disposed radial spines; therefore they may be called "social Monosphærida," or better "polyzoic Ethmosphærida." ”

“ Spongy framework very compact, with very small meshes, about as thick as the radius of the spherical medullary shell. Polar spines very strong, three-sided pyramidal, about as long as the breadth of the cortical shell, as broad at the base as the medullary shell. ”

“ Definition.—Astrosphærida with two concentric latticed medullary shells, connected by radial beams; the outer is immediately enveloped by the spongy framework, and bears numerous radial spines.
The genus Spongosphæra (in the definition here restricted) differs from Spongopila in the double medullary shell, which in the latter is simple; it exhibits to the latter the same relation that Spongodictyon among the Liosphærida bears to Spongoplegma. The outer medullary shell of Spongosphæra is immediately enveloped by the spongy wicker-work, which everywhere pierces the wall of the central capsule. ”

“ It grows according to the enveloping skeleton, but remains constantly smaller. The form of the central capsule is circular (lenticular or discoidal) in the Spongophacida and Spongotrochida, whilst in the Spongobrachida it enters into the radial spongy arms, developed from the margin of the spongy disk.
Synopsis of the Genera of the Spongodiscida. Subfamily 1. Spongophacida, Haeckel, 1881, Prodromus, p. 461. Definition.—Spongodiscida with a simple circular disk, without radial appendages on the margin (neither solid spines nor chambered arms) . ”

“ Definition.—Spongurida with ellipsoidal or cylindrical shell of solid spongy framework, without internal cavity and without latticed medullary shell. On the poles of the axis occur two opposite strong spines.
The genus Spongoprunum differs from the most nearly allied Spongurus by the possession of two strong solid spines, lying in the axis of the ellipsoidal or cylindrical massive spongy shell, on its two opposite poles. Spongoprunum bears therefore the same relation to Spongurus that Ellipsoxiphus does to Cenellipsis. ”

“ From each spine arise ten to twelve verticils of lateral branches; each verticil composed of three forked branches. The proximal larger branches ramify richly, and form by their connection the loose spongy framework of the spherical shell; the distal smaller branches are simple or bifurcated, and the ramules are provided with an elegant spathillum at the end (fig. 4) . Entire surface of the spongy sphere covered with innumerable bristle-shaped radial spines (half as long as the cavity radius) , zig-zag, bent, with beards, and with a spathillum at the end. ”

“ Radius of the spherical shell-cavity half as great as the thickness of the loose spongy shell-wall. Inside and outside of the wall rough spongy, not closed by a lattice-plate. Meshes ten to twenty times as broad as the bars. ”

“ Spongy framework of the solid sphere rather compact, everywhere of the same structure, with roundish, nearly equal meshes, six to eight times as broad as the bars. Surface rough with prominent thorns. ”

“ Habitat.—Cosmopolitan; common in all warmer seas, surface.
2. Spongosphæra polyacantha, J. Müller.
Spongosphæra polyacantha, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 32, Taf. iv. figs. 1-4.
Spongy shell spherical, with ten to twenty large radial spines, which arise with thinner bases from the medullary shell, and are prominent on the surface at different lengths; they are three-sided prismatic (not four-sided) , with three leaf-shaped straight edges. Whilst the spongy framework is much looser than in the preceding species, both medullary shells have nearly the same shape. ”