Sphærozoum bacillosum, Haeckel, 1881, Manuscript.
Spicula all simple rods, straight cylindrical, obtuse at both ends, quite smooth. Central capsule pellucid, with one single central oil-globule.
Dimensions.—Diameter of the central capsule 0.08 to 0.12, length of the spicula 0.05 to 0.08.
Habitat.—Central Pacific, Station 271, surface.
2. Belonozoum spinulosum, Haeckel.
Sphærozoum spinulosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 54, Taf. viii. fig. 4.
Sphærozoum spinulosum, Haeckel, 1862, Monogr. d. Radiol., p. 527, Taf. xxxiii. figs. 3, 4.
Spicula all simple rods, straight cylindrical, obtuse on both ends, thorny with numerous small spines, placed vertically on the rods.
Dimensions.—Diameter of the central capsule 0.08 to 0.1, length of the spicula 0.05 to 0.2.
Habitat.—Mediterranean, Nice, J. Müller; Messina, Haeckel; Naples, Brandt; surface.
3. Belonozoum italicum, Haeckel.
Sphærozoum italicum, Haeckel, 1862, Monogr. d. Radiol., p. 526, Taf. xxxiii. figs. 1, 2.
Spicula all simple rods, more or less curved or bent, pointed at both ends, quite smooth. Central capsule with a variable number (commonly five to twenty) of oil-globules.
Dimensions.—Diameter of the central capsule 0.1 to 0.3, length of the spicula 0.05 to 0.2.
Habitat.—Mediterranean, Nice, Naples, Messina, Haeckel, surface.
4. Belonozoum atlanticum, n. sp.
Sphærozoum atlanticum, Haeckel, 1881, Manuscript.
Spicula all together simple rods, more or less curved or bent, pointed at both ends, thorny from numerous small spines, placed vertically on the rods.
Dimensions.—Diameter of the central capsule 0.1 to 0.2, length of the spicula 0.07 to 0.15.
Habitat.—Tropical Atlantic, Station 348, surface.
Definition.—Sphærozoida with branched or radiate spicula of one kind.
The genus Sphærozoum, with Physematium one of the two oldest Radiolaria, observed in the living state, was founded 1834 by Meyen for one of the social Beloidea, which was probably the common cosmopolitan Sphærozoum punctatum, the true type of this genus. Johannes Müller described a number of species, which were partly skeletonless (Collozoum), partly armed with simple or with compound spicula. The species with simple spicula we refer here to Belonozoum, the species with two or more different kinds of spicula to Rhaphidozoum, while we unite in Sphærozoum all species with one kind of branched or compound spicula. The two following species are incompletely known:—Sphærozoum orientale, Dana, 1863, Ann. and Mag. Nat. Hist., vol. xii. p. 54. Sphærozoum sanderi, Dœnitz, 1871, L. N. 60, p. 71.
Definition.—Spicula radiate, not geminate, consisting of three, four, or more needles or shanks, radiating in different directions from one common central point.
1. Sphærozoum triactinium, n. sp.
Spicula all (or nearly all) triradiate, composed of three (or sometimes in few spicula four) needle-like shanks, diverging from one common point. Shanks straight or somewhat curved, smooth, pointed. Central capsules spherical, with one central oil-vesicle. This species may be regarded as the social form of Thalassoxanthium triactinium.
Dimensions.—Diameter of the central capsules 0.1 to 0.12, length of the spicula-shanks 0.05 to 0.1.
Habitat.—South Pacific, Station 295, surface.
2. Sphærozoum medusinum, n. sp.
Spicula all (or nearly all) quadriradiate, composed of four (or sometimes in few spicula three) needle-like shanks (mostly of unequal length), diverging from one common point. Shanks slightly curved, pointed, thorny, covered with small spinules. Central capsules ellipsoidal, containing several (four to eight) oil-vesicles. This species may be regarded as the social form of the solitary Thalassoxanthium medusinum (Pl. 2, fig. 5).
Dimensions.—Diameter of the central capsules 0.15 to 0.18, length of the spicula-shanks 0.08 to 0.12.
Habitat.—North Pacific, Station 236, surface.
3. Sphærozoum hamatum, n. sp.
Spicula all (or nearly all) quadriradiate, composed of four (or sometimes in few spicula three) needle-like shanks, mostly of very different size, diverging from one common point. Shanks strong, straight, curved, or hook-like; thorny, covered with small spinules on the distal extremity. Central capsules ellipsoidal, large, containing many (ten to twenty) oil-globules. This large species is distinguished by the very irregular form and size of the spicula.
Dimensions.—Diameter of the central capsules 0.2 to 0.25, length of the spicula-shanks 0.12 to 0.18.
Habitat.—Central Pacific, Station 265, surface.
4. Sphærozoum hexactinium, n. sp.
Spicula all (or nearly all) hexaradiate, composed of six (or sometimes in few spicula five or seven) needle-like shanks, mostly of equal size, diverging from one common point in two opposite hemispheres (three needles upwards, three needles downwards). Shanks somewhat curved, pointed, smooth. Central capsules spherical, small, with one central oil-globule. This species may be regarded as the social form of Thalassoxanthium hexactinium.
Dimensions.—Diameter of the central capsule 0.06 to 0.08, length of the spicula-shanks 0.05 to 0.06.
Habitat.—North Atlantic, Færöe Channel (Gulf Stream), John Murray.
Definition.—Spicula all geminate-radiate, consisting of one middle rod, which bears an equal and constant number of rays (two, three, or four) at each end.
5. Sphærozoum furcatum, n. sp.
Spicula all (or nearly all) geminate and simply forked, composed of a simple axial rod and two simple needle-like shanks on each end of it. Shanks straight, pointed, smooth, commonly somewhat longer than the middle rod.
Dimensions.—Diameter of the central capsules 0.1 to 0.15, length of the axial rod of the spicula 0.03, of its shanks 0.04 to 0.06.
Habitat.—Tropical zone of the Atlantic, near Ascension Island, Station 344, surface.
6. Sphærozoum furculosum, n. sp.
Spicula all (or nearly all) geminate and simply forked, composed of a simple axial rod and two simple needle-like shanks on each end of it. Shanks curved or bent, pointed, thorny, with many small spinules, commonly somewhat shorter than the middle rod.
Dimensions.—Diameter of the central capsules 0.2 to 0.25, length of the axial rod of the spicula 0.1, of its shanks 0.05 to 0.08.
Habitat.—South Atlantic, near Tristan da Cunha, Station 334, surface.
7. Sphærozoum ovodimare, Haeckel.
Sphærozoum ovodimare, Haeckel, 1862, Monogr. d. Radiol., p. 527, Taf. xxxiii. figs. 5, 6.
Sphærozoum punctatum, var., Brandt, 1881, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, Taf. i. fig. 54.
Spicula all (or nearly all) geminate and triradiate, composed of a long simple axial rod and three simple needle-like shanks on each end of it. Shanks straight, pointed, smooth, commonly shorter than the middle rod. (Often few furcate or four-rayed spicula are intermixed, or few spicula are not smooth, but thorny.)
Dimensions.—Diameter of the central capsules 0.05 to 0.2, length of the middle rod of the spicula 0.02 to 0.06, of its shanks 0.01 to 0.04.
Habitat.—Mediterranean, Naples, Messina, Haeckel; Atlantic, Canary Islands, Cape Verde Islands, West Coast of Africa, Stations 351 to 354; surface.
8. Sphærozoum trigeminum, n. sp.
Spicula all (or nearly all) geminate-triradiate, composed of a short simple axial middle rod and three simple needle-like shanks on each end of it. Shanks curved or bent, very thin, smooth, commonly much longer than the middle rod. (Often few quadriradiate or few thorny triradiate spicules are interspersed among the others.)
Dimensions.—Length of the middle rod of the spicula 0.02 to 0.04, of its shanks 0.03 to 0.09.
Habitat.—North Pacific, Stations 244 to 248, surface.
9. Sphærozoum punctatum, J. Müller.
Sphærozoum punctatum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 54, Taf. viii. figs. 1, 2.
Sphærozoum punctatum, Haeckel, 1862, Monogr. d. Radiol., p. 528, Taf. xxxiii. figs. 7-9.
Sphærozoum fuscum, Meyen, 1834, Nova Acta Acad. Nat. Cur., vol. xvi. Taf. xxxviii. fig. 7.
Thalassicolla punctata, Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 434, pl. xvi. figs. 1, 2, 3.
Spicula all (or nearly all) geminate-triradiate, composed of a long simple axial middle rod and three simple needle-like shanks on each end of it. Shanks straight, pointed, thorny, with many small spines, commonly somewhat shorter than the middle rod. (Often few furcate or four-rayed spicula are intermingled, or some of the spicula are smooth.) This cosmopolitan species is extremely variable, and produces interesting transitional forms to many other species of the genus. Compare also the general remarks on the genus, and the chapter on "Transformation" in the general introduction.
Dimensions.—Length of the middle rod of the spicula 0.02 to 0.06, of its shanks 0.01 to 0.05.
Habitat.—Cosmopolitan, common in nearly all warmer seas, Mediterranean, Atlantic, Indian Ocean, Pacific; surface.
10. Sphærozoum armatum, n. sp. (Pl. 4, fig. 9).
Spicula all geminate-triradiate, with a stout and short middle rod and three arborescent shanks on each end of it. Shanks longer than the middle rod, very stout, straight, pine-shaped, with six to twelve irregular, spinulated, lateral branches.
Dimensions.—Diameter of the central capsules 0.04 to 0.08, length of the middle rod of the spicula 0.02 to 0.03, of its shanks 0.05 to 0.08.
Habitat.—North Pacific, Japan, Station 239, surface.
11. Sphærozoum alveolatum, n. sp. (Pl. 4, figs. 2, 3).
Spicula all together geminate-triradiate, with a simple stout middle rod and three arborescent shanks on each end of it. Shanks more or less curved, slender, pine-shaped, with four to eight short, thorny lateral branches. In all cœnobia of this remarkable species the central capsules are enclosed in large thick-walled alveoles (of three times their breadth), and in each alveole is placed besides the capsule one single very large spiculum, whilst the others are much smaller (fig. 3). All the alveolated capsules are placed in one single stratum on the surface of the jelly-like spherical cœnobium, comparable to the blastoderm-cells of a blastula.
Dimensions.—Diameter of the central capsules 0.08 to 0.1, of the alveoles 0.2 to 0.4, length of the spicula 0.1 to 0.3.
Habitat.—South Pacific (Juan Fernandez), Station 300, surface.
12. Sphærozoum verticillatum, n. sp. (Pl. 4, fig. 7).
Spicula all geminate-triradiate, with a short simple middle rod and three much longer arborescent shanks on each end of it. Shanks straight, slender, pine-shaped, each in the distal half with three to four elegant verticils of thorny lateral branches.
Dimensions.—Diameter of the capsules 0.1 to 0.12, middle rod of the spicula 0.03 to 0.05, shanks 0.1 to 0.15.
Habitat.—Indian Ocean, Ceylon, Haeckel; Madagascar, Rabbe; surface.
13. Sphærozoum octoceras, n. sp.
Spicula all geminate-quadriradiate, with a short simple middle rod and four diverging shanks on each end of it. Shanks smooth, irregularly curved or bent, three to six times as long as the middle rod. It may be regarded as the social form of Thalassoxanthium octoceras (Pl. 2, fig. 6).
Dimensions.—Diameter of the capsules 0.12 to 0.16, middle rod of the spicula 0.02, shanks 0.01.
Habitat.—Australia, south coast, Faber; Station 163, surface.
14. Sphærozoum quadrigeminum, n. sp.
Spicula all geminate-quadriradiate, with a long thick middle rod and four shorter diverging shanks on each end of it. Shanks straight, thorny.
Dimensions.—Diameter of the capsules 0.06 to 0.08, length of the spicula 0.05 to 0.15.
Habitat.—North Atlantic, Azores, Station 354, surface.
15. Sphærozoum araucaria, n. sp.
Spicula all geminate-quadriradiate, with stout straight middle rod and four longer diverging shanks on each end of it. Shanks arborescent, with six to twelve thorny lateral branches.
Dimensions.—Diameter of the capsules 0.1 to 0.15, length of the spicula 0.05 to 0.1.
Habitat.—South Atlantic, coast of Brazil, Rabbe; surface.
16. Sphærozoum arborescens, n. sp. (Pl. 4, fig. 8).
Spicula all geminate-quadriradiate, with a stout straight middle rod and four longer diverging shanks on each end of it. Shanks arborescent, pine-shaped, with four to six verticils of lateral branches, which again are ramified and thorny.
Dimensions.—Diameter of the capsules 0.16 to 0.18, length of the spicula 0.1 to 0.2.
Habitat.—South Atlantic (Tristan da Cunha), Station 332, surface.
Definition.—Spicula all geminate-radiate, but with a different and variable number of shanks on each end of the middle rod.
17. Sphærozoum stellatum, n. sp.
Spicula all geminate-radiate, with a strong middle rod and a variable number of shorter radiating shanks on the two ends of it. Shanks straight, nearly conical, smooth; for the most part three or four shanks on each end, but sometimes also five or six; very often this number is unequal on the two ends.
Dimensions.—Diameter of the central capsules 0.1 to 0.2, length of the spicula 0.05 to 0.15.
Habitat.—Central Pacific, Station 270, surface.
18. Sphærozoum geminatum, n. sp. (Pl. 4, fig. 4).
Spicula all geminate-radiate, with a strong middle rod and a variable number of longer radiant shanks on each end of it. Shanks straight, conical, in the distal half thorny; commonly either three or four shanks on each end of the middle rod, often also three on one end, four on the other end; rarely five or six rays on one end.
Dimensions.—Diameter of the capsules 0.15 to 0.2, length of the spicula 0.05 to 0.1.
Habitat.—Indian Ocean, Ceylon, Haeckel; surface.
19. Sphærozoum circumtextum, n. sp.
Spicula all geminate-radiate, with a very variable number of rays (two to six) on each end of the thin middle rod. All spicula very thin and delicate, smooth, with curved or bent shanks, densely covering the central capsule like a cobweb. The number of rays on each end is usually different, generally four or five, often also two or three, rarely six.
Dimensions.—Diameter of the capsule 0.1 to 0.2, length of the spicula 0.04 to 0.12.
Habitat.—Southeast part of the Indian Ocean, Station 160, surface.
20. Sphærozoum variabile, n. sp. (Pl. 4, fig. 5).
Spicula all geminate-radiate, with a short middle rod and a variable number of shanks on each end of it. Shanks four to eight times as long as the middle rod, curved or bent, in the distal half thorny; their number is commonly different on the two ends of it, three or five, often also four or six, rarely two; their size and form very variable.
Dimensions.—Diameter of the capsules 0.1 to 0.3, length of the spicula 0.1 to 0.2.
Habitat.—North Pacific, Station 248, surface.
Definition.—Sphærozoida with two or more different kinds of spicula; one kind simple, needle-shaped; the other kinds compound, radiate, or branched.
The genus Rhaphidozoum differs from Sphærozoum by the composition of the skeleton of two or more different kinds of spicula, and has therefore the same relation to it as the solitary Lampoxanthura to Lampoxanthella.
In some species nearly all the different forms, which characterise the numerous species of Beloidea, may be united in one and the same individual.
Definition.—Spicula of two different kinds; one kind simple, needle-shaped, the other radiate (composed of three, four, or more shanks, diverging from one common point).
1. Rhaphidozoum pelagicum, n. sp.
Spicula of two different kinds; one kind simple thin needles, a little curved or bent, the other kind triradiate, with three thin, curved shanks. Both kinds smooth, without thorns. Resembles a combination of Belonozoum italicum and Sphærozoum triactinium.
Dimensions.—Diameter of the central capsules 0.1 to 0.12, length of the spicula 0.05 to 0.15.
Habitat.—Central Pacific, Station 267, surface.
2. Rhaphidozoum pacificum, n. sp.
Spicula of two different kinds; one kind simple needles, stout and straight, pointed at both ends, the other kind triradiate, with three straight and stout shanks. Both kinds thorny.
Dimensions.—Diameter of the central capsule 0.06 to 0.08, length of the spicula 0.05 to 0.1.
Habitat.—Central Pacific, Station 271, surface.
3. Rhaphidozoum acuferum, Haeckel.
Rhaphidozoum acuferum, Haeckel, 1862, Monogr. d. Radiol., p. 529, Taf. xxxii. figs. 9-11.
Sphærozoum acuferum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 54, Taf. viii. fig. 3.
Thalassicolla acufera, J. Müller, 1855, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 237.
Spicula of two different kinds, simple needles and quadriradiate; both strong, thorny, covered with small spinules. Simple needles mostly curved, C-shaped. Four shanks of the quadriradiate spicula now straight, now curved, commonly of very different size. (Often one single quadriradiate spiculum is distinguished by its extraordinary size.) For the detailed description of this species compare my Monograph (loc. cit.).
Dimensions.—Diameter of the central capsules 0.05 to 0.35, length of the simple needles 0.05 to 0.25, shanks of the quadriradiate spicula 0.05 to 0.15.
Habitat.—Mediterranean, Messina, Naples, Nice.
4. Rhaphidozoum arachnoides, n. sp.
Spicula of two different kinds; one kind simple, needle-like, the other quadriradiate; both very thin and slender, smooth, without spicules. Simple needles curved, C-shaped. Four shanks of the quadriradiate spicula also curved, commonly of nearly equal size. The numerous thread-like spicula of this species are so densely packed around the central capsule, that they extend all around its surface like the network round a balloon.
Dimensions.—Diameter of the central capsules 0.12 to 0.15, length of the simple needles 0.1 to 0.12, shanks of the quadriradiate spicula 0.06 to 0.08.
Habitat.—Tropical Atlantic, Station 345, surface.
5. Rhaphidozoum asperum, n. sp.
Spicula of two different kinds; one kind simple, needle-shaped, stout, and straight, the other kind hexaradiate; its six shanks about half as long as the former, conical. Both kinds very thorny, covered with short conical spinules.
Dimensions.—Diameter of the capsules 0.06 to 0.08, length of the simple needles 0.05 to 0.07, shanks of the hexaradiate spicula 0.03 to 0.04.
Habitat.—South Pacific, Station 288, surface.
Definition.—Spicula of two different kinds; one kind simple, needle-shaped, the other kind geminate-radiate, with rays on both poles of a middle rod.
6. Rhaphidozoum neapolitanum, Haeckel.
Sphærozoum neapolitanum, C. Brandt, 1881, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 390, Taf. i. figs. 14, 16-18.
Spicula mixed, of two different kinds; simple needles and geminate-forked. Simple rods, like those of Belonozoum italicum, more or less curved, pointed at both ends, smooth (sometimes a little thorny at both ends). Geminate spicula simply forked, like those of Sphærozoum furcatum, composed of a short, simple, axial rod, and two simple, smooth, straight shanks on each end of it, commonly somewhat longer than the middle rod. This species, which I have observed myself in Spezzia in great quantity, is quite as variable as all the other species of the genus, and has not more claim to specific rights than the others. Commonly the simple needles are much more numerous than the geminate-forked, but sometimes the contrary is the case. On their variability compare the general remarks on the genus, and the chapter on "Transformation" in the general introduction.
Dimensions.—Length of the simple spicula 0.05 to 0.1, of the middle rod of the forked spicule 0.05 to 0.08, of their shanks 0.01 to 0.03.
Habitat.—Mediterranean, Naples, Spezzia, surface.
7. Rhaphidozoum patagonicum, n. sp.
Spicula mixed, of two different kinds, simple needles and geminate-triradiate. Simple rods, like those of Belonozoum spinulosum, straight, thorny, pointed at both ends. Geminate spicula double-triradiate, like those of Sphærozoum punctatum, composed of a simple, short, axial rod and three simple pointed shanks on each end of it. Shanks straight, thorny, with many small spinules, commonly somewhat longer than the middle rod. (Often some of the spicula of both kinds are smooth, not thorny, or not straight, but a little curved, or a few forked or four-radiated geminate spicula are mingled with the others.)
Dimensions.—Diameter of the central capsules 0.08 to 0.2, length of the simple spicula 0.1 to 0.15, of the geminate 0.08 to 0.16.
Habitat.—South Pacific, west coast of Patagonia, Station 302, surface.
8. Rhaphidozoum ascensionis, n. sp.
Spicula mixed, of two different kinds, simple needles and geminate-triradiate; both kinds thin, smooth, without spinules. Simple needles somewhat curved, C- or S-shaped. Geminate spicula double-triradiate, composed of a simple, short, straight axial rod and three slender curved shanks on each end of it. Shanks two to four times longer than the middle rod. (Sometimes few simple hexaradiate and geminate tetraradiate spicula are mingled.)
Dimensions.—Diameter of the central capsules 0.12 to 0.15, length of the simple spicula 0.1, of the double-triradiate 0.05 to 0.2.
Habitat.—South Atlantic, off Ascension Island, Station 342, surface.
9. Rhaphidozoum capense, n. sp.
Spicula of two different kinds; one kind simple, needle-shaped, straight, pointed at both ends, the other kind geminate-quadriradiate, with a stout short middle rod and four longer bent shanks on each end of it. Both kinds smooth.
Dimensions.—Diameter of the capsules 0.2 to 0.25, length of the simple needles 0.01 to 0.3, of the geminate spicula 0.05 to 0.15.
Habitat.—Cape of Good Hope (Agulhas), Station 142, surface.
10. Rhaphidozoum australe, n. sp.
Spicula of two different kinds; one kind simple, needle-shaped, curved, thin; the other kind geminate, with a variable number of shanks on both ends of the shorter middle rod, often different on the two poles of it. The prevalent number of rays on each end is three or four, often also two or five, rarely six. All spicula smooth, more or less bent.
Dimensions.—Diameter of the capsules 0.1 to 0.2, length of the spicula 0.05 to 0.15.
Habitat.—South West Pacific, Station 165, surface.
Definition.—Spicula of three different kinds: one kind simple, needle-shaped; the second kind radiate, with three to six shanks radiating from a common central point; the third kind geminate-radiate, with rays on both poles of a middle rod.
11. Rhaphidozoum polymorphum, n. sp.
Spicula of three different kinds; simple needles, radiate, and geminate mixed. The simple needles straight and stout. The radiate spicula commonly with three or six, rarely four or five, rays. The geminate-radiate spicula prevalent, with three or four, rarely two or five, shanks on each end of the middle rod. Number very variable. All shanks straight and smooth.
Dimensions.—Diameter of the capsule 0.1 to 0.2, length of the spicula 0.05 to 0.15.
Habitat.—South Pacific, Station 295, surface.
12. Rhaphidozoum pandora, n. sp. (Pl. 4, fig. 6).
Spicula of three different kinds; simple needles, radiate and geminate mixed. The simple needles thin spindle-shaped, often curved. The radiate spicula commonly with three or four, rarely five or six, curved rays. The geminate-radiate spicula commonly with three or four, rarely two or five, shanks on each end, often different on the two ends of the middle rod. Number and form very variable. All or most of the shanks more or less bent and thorny.
Dimensions.—Diameter of the capsule 0.1 to 0.3, length of the spicula 0.05 to 0.2.
Habitat.—South Atlantic (near Ascension Island), Station 343, surface.
Sphærellaria, Haeckel, 1881, Prodromus, p. 421.
Sphæridea vel Peripylea, Hertwig, 1879, Organismus der Radiol., p. 133.
Definition.—Spumellaria with latticed or spongy shell.
The order Sphærellaria, the second order of Radiolaria, comprises all those Spumellaria in which the skeleton is a latticed or fenestrated, often more or less spongy, siliceous shell. Originally this shell is a simple extracapsular lattice-sphere, in which the central capsule is included; from this simple ancestral form an enormous mass of different and often very complicated forms is derived; this order is by far the largest, and in morphological respects the most important and most interesting, of all Radiolaria. It contains not less than twenty-eight different families, three hundred and five genera, and more than sixteen hundred species.
In my Monograph (1862) seven families appertaining to this group are described—the Ethmosphærida, Cladococcida, Ommatida, Spongurida, Discida, Lithelida, and Collosphærida. The astonishing increase of this group by the detection of a large series of new and interesting forms, and particularly of important connecting forms between very different branches of it, now enables me to give a much better arrangement. I discern now four suborders or sections of Sphærellaria, according to the different geometrical form of the central capsule and of the latticed shell enveloping it. The first of these, and the common ancestral group of the whole order, is the Sphæroidea, with spherical capsule; in the Prunoidea it becomes ellipsoidal or cylindrical by prolongation of one axis; in the Discoidea lenticular or discoidal by shortening of one axis; in the Larcoidea lentelliptical, or triaxon-ellipsoid, by different growth of the capsule in three different "dimensive axes."
| Central capsule spherical. | brace | Shell a simple sphere or a system of concentric spheres, | 1. Sphæroidea. |
| Central capsule ellipsoidal or cylindrical. | brace | Shell a simple ellipsoid or a cylinder with annular transverse constrictions, | 2. Prunoidea. |
| Central capsule lenticular or discoidal. | Shell a biconvex lens or a flat disk, | 3. Discoidea. | |
| Central capsule lentelliptical or triaxon. | brace | Shell a triaxon-ellipsoid, with three different axes, | 4. Larcoidea. |
| Central capsule spherical. | ||||
| Shell a simple sphere or a system of concentric spheres, | ||||
| 1. Sphæroidea. | ||||
| Central capsule ellipsoidal or cylindrical. | ||||
| Shell a simple ellipsoid or a cylinder with annular transverse constrictions, | ||||
| 2. Prunoidea. | ||||
| Central capsule lenticular or discoidal. | ||||
| Shell a biconvex lens or a flat disk, | ||||
| 3. Discoidea. | ||||
| Central capsule lentelliptical or triaxon. | ||||
| Shell a triaxon-ellipsoid, with three different axes, | ||||
| 4. Larcoidea. | ||||
Sphæroida, Sphæridea, Sphærida, Haeckel, 1878, Protistenreich, p. 103.
Sphæridea, R. Hertwig, 1879, Organismus der Radiol., p. 39.
Definition.—Spumellaria with spherical central capsule (very rarely somewhat modified, or allomorphous); with spherical fenestrated siliceous shell (often an endospherical polyhedron, very rarely of more modified, subspherical form or allomorphous). Growth of the shell in the three dimensive axes equal.
The suborder Sphæroidea, the first and most important of the four of the Sphærellaria, comprises those Spumellaria in which the original geometrical 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 great majority of Sphæroidea there is no external indication of the three dimensive axes; but in many forms they are indicated by the regular position of certain external radial spines or internal radial beams. However, in no case are those three axes expressed in the form of the shell itself and of the enclosed spherical central capsule; this is the main character by which the Sphæroidea differ from the following sections:—Prunoidea, Discoidea, Larcoidea, all three of which arise from them.
The section Sphæroidea, in the sense here restricted, was founded by me in my Protistenreich (1878, p. 103) and adopted by Hertwig (1879) in his Organismus der Radiolarien (p. 39). The different groups appertaining to this large section were characterised more accurately in my Prodromus (1881, pp. 448-456); there I gave the characters of six subfamilies with thirty tribes, containing ninety-three genera. Formerly, in my Monograph (1862), the Sphæroidea were disposed in five different families:—Ethmosphærida, Cladococcida, Ommatida, Spongosphærida, Collosphærida. 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. 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; secondly, the number of the concentric latticed spheres, which are connected by radial beams. I give here the preference to the first principle, whilst in my Prodromus (1881) I had preferred the second. The question, which of the two principles is more important for the classification of Sphæroidea, is very difficult to answer; probably in many cases the former, in many the latter is more important for their phylogeny.
Regarding the number of the concentric shells which compose the latticed carapace of the Sphæroidea, we can distinguish six families, viz.:—
VIII. Monosphærida (with one single shell).
VIII. Dyosphærida (with two concentric shells).
VIII. Triosphærida (with three concentric shells).
IIIV. Tetrasphærida (with four concentric shells).
IIIV. Polysphærida (with five or more concentric shells).
IIVI. Spongosphærida (with spongy shells).
On the other hand, regarding the number of the radial spines and their regular disposition on the shell-surface, we can distinguish five families, viz.:—
VIII. Liosphærida (without radial spines).
VIII. Stylosphærida (with two radial spines, opposite in one axis).
VIII. Staurosphærida (with four radial spines, opposite in pairs in two axes, perpendicular one to another).
IIIV. Cubosphærida (with six radial spines, opposite in pairs in the three dimensive axes).
IIIV. Astrosphærida (with numerous—eight, twelve, twenty, or more—radial spines, often more than a hundred).
All five latter groups contain representatives of all six former groups; therefore we get together not less than thirty different subfamilies of Sphæroidea, already enumerated in my Prodromus, 1881, p. 449. I repeat them here to give a better survey of the system there employed.
| Families and Subfamilies of SPHÆROIDEA. | Liosphærida (anacantha). |
Stylosphærida (diacantha). |
Staurosphærida (tetracantha). |
Cubosphærida (hexacantha). |
Astrosphærida (polyacantha). |
|---|---|---|---|---|---|
| Monosphærida. (One single shell.) |
Ethmosphærida. | Xiphostylida. | Staurostylida. | Hexastylida. | Coscinommida. |
| Dyosphærida. (Two concentric shells.) |
Carposphærida. | Sphærostylida. | Staurolonchida. | Hexalonchida. | Haliommida. |
| Triosphærida. (Three concentric shells.) |
Thecosphærida. | Amphistylida. | Stauracontida. | Hexacontida. | Actinommida. |
| Tetrasphærida. (Four concentric shells.) |
Cromyosphærida. | Cromyostylida. | Staurocromyida. | Hexacromyida. | Cromyommida. |
| Polysphærida. (Five or more concentric shells.) |
Caryosphærida. | Caryostylida. | Staurocaryida. | Hexacaryida. | Arachnommida. |
| Spongosphærida. (Spongy shells.) |
Plegmosphærida. | Spongostylida. | Staurodorida. | Hexadorida. | Spongiommida. |
| Families and Subfamilies of SPHÆROIDEA. | Liosphærida (anacantha). |
Stylosphærida (diacantha). |
Staurosphærida (tetracantha). |
|---|---|---|---|
| Monosphærida. (One single shell.) |
Ethmosphærida. | Xiphostylida. | Staurostylida. |
| Dyosphærida. (Two concentric shells.) |
Carposphærida. | Sphærostylida. | Staurolonchida. |
| Triosphærida. (Three concentric shells.) |
Thecosphærida. | Amphistylida. | Stauracontida. |
| Tetrasphærida. (Four concentric shells.) |
Cromyosphærida. | Cromyostylida. | Staurocromyida. |
| Polysphærida. (Five or more concentric shells.) |
Caryosphærida. | Caryostylida. | Staurocaryida. |
| Spongosphærida. (Spongy shells.) |
Plegmosphærida. | Spongostylida. | Staurodorida. |
| Families and Subfamilies of SPHÆROIDEA. | Cubosphærida (hexacantha). |
Astrosphærida (polyacantha). |
|---|---|---|
| Monosphærida. (One single shell.) |
Hexastylida. | Coscinommida. |
| Dyosphærida. (Two concentric shells.) |
Hexalonchida. | Haliommida. |
| Triosphærida. (Three concentric shells.) |
Hexacontida. | Actinommida. |
| Tetrasphærida. (Four concentric shells.) |
Hexacromyida. | Cromyommida. |
| Polysphærida. (Five or more concentric shells.) |
Hexacaryida. | Arachnommida. |
| Spongosphærida. (Spongy shells.) |
Hexadorida. | Spongiommida. |